Latest ESO telbib papers

Supersolar Metallicity and Tentative Evidence for Photochemistry on WASP-96 b from JWST and Ground-based VLT Transmission Spectroscopy

First Author: Radica, Michael
Instruments: FORS2
ProgramIDs: 199.C-0467
BibCode: 2026AJ....171..314R

With its expanded wavelength coverage and increased precision compared to previous space-based observatories, JWST provides the opportunity to revisit benchmark planets and view them in a new light. Here, we conduct an in-depth study of the atmosphere of the hot-Saturn WASP-96 b combining a new JWST NIRSpec/G395H transit with archival NIRISS/SOSS and Very Large Telescope/FORS2 transmission spectra. The combined spectrum shows clearly visible features from H₂O, CO₂, and Na. CO, though, remains unconstrained, precluding a firm metallicity derivation from free retrievals alone. However, self-consistent grids yield a broadly superstellar atmospheric metallicity of 2─6× stellar. When combined with a roughly stellar C/O ratio ( 0.41−0.09+0.10 from self-consistent grids), we find that WASP-96 b potentially formed via core-accretion beyond the H₂O snowline and subsequently accreted volatile-rich material. Free retrievals also find a moderate preference ( lnB = 2.69) for models with SO₂ versus without. WASP-96 b falls directly on the proposed "SO₂ shoreline" and the retrieved SO₂ abundance is well-matched to predictions from photochemical models. Our combined spectrum displays an optical slope, which our models fit with opacity from scattering aerosols—either small-particle condensate clouds or photochemical hazes—though we cannot completely rule out the broad wings of Na or the effects of stellar contamination. Future observations are necessary to disentangle these effects. Finally, we explore the possibility for limb asymmetry in WASP-96 b's transmission spectrum and provide several tests to identify asymmetries in our data. We encourage the community to prioritize the development of a robust pathway to quantify the presence of limb asymmetry—particularly for low signal-to-noise cases.

The asymmetric structure of the inner disc around HD 142527 A with VLTI/MATISSE

First Author: Scheuck, M. B.
Instruments: GRAVITY, MATISSE, PIONIER
ProgramIDs: 108.225V, 111.254P, 190.C-0963, 106.21Q8, 098.D-0488
BibCode: 2026A&A...708A.380S

Context. Circumstellar discs, and especially their inner regions, which cover ranges from less than 1 au to a few au, are the birthplaces of terrestrial planets. The inner regions are thought to be as diverse in structure as the well-observed outer regions probed by ALMA. Aims. By combining data and results from previous studies using the VLTI/PIONIER and VLTI/GRAVITY instruments with new, multi-epoch VLTI/MATISSE observations, we aim to provide a comprehensive picture of the structure of the inner regions of the circumstellar disc around the F-type Herbig Ae/Be star HD 142527 A, the primary of a binary star system. Methods. We modelled the multi-wavelength interferometric data using a parametrised, geometrically thin disc model, allowing for azimuthal asymmetry, and exploring a first-order disc modulation and an off-centre Gaussian component. Results. We find time-variable structures in the N-band observables, which we reproduce with time-dependent models. This variability manifests as azimuthally asymmetric emission, evidenced by strong, non-zero closure phases in the N-band data. Fits to individual epochs of the N-band observations yield better χ²_r values than fits to all epochs simultaneously. This suggests substantial changes in the geometry of the inner disc emission from ∼1 au up to a few astronomical-unit scales from one year to the next. Moreover, our models produce a very close-in inner disc rim R_rim ≍ 0.1 au. Altogether, we find a very complex, substantially non-point symmetric and temporally variable disc (r_out ≲ 6 au) around the primary. Conclusions. The very close-in inner rim indicates the presence of material within the typical wall-like sublimation radius, R_{rim,literature} ≍ 0.3 au. The complex, temporally variable inner-disc geometry is likely affected, or even caused by, the close passage (∼5 au) and short orbit (P ≍ 24 yr) of the companion HD 142527 B.

A New Cloud─Cloud Collision Source N68 toward the G35 Molecular Cloud Complex

First Author: Chen, En
Instruments: LABOCA
ProgramIDs: 085.F-9526, 085.F-9505, 082.F-9701, 080.F-9701, 081.C-9501, 079.C-9501, 078.F-9040, 181.C-0885
BibCode: 2026ApJ..1001..230C

Bubble N68 in the G35 complex shows clear cloud─cloud collision (CCC) signatures. Its semiring-like morphology harbors many significant massive star formation tracers: 6 H II regions, 4 6.7 GHz masers, 5 Midcourse Space Experiment sources, 9 radio peaks, and nearly 10 O/B-type stars. We also identified 163 young stellar objects (45 Class I, 5 Flat, 113 Class II), indicating active star formation toward N68. Our molecular study with CO reveals two distinct molecular clouds (N68a: 47─56 km s⁻¹; N68b: 56─64 km s⁻¹), with broad bridge features and complementary distributions at their borders, indicating an ongoing CCC. Star formation in N68 is collectively driven by collect-and-collapse (CC), radiation-driven implosion, and CCC mechanisms. However, compared with the CC and radiation-driven implosion mechanisms, the CCC mechanism does not enhance the star formation efficiency; instead, it tends to trigger the formation of massive stars. N68, along with bubbles N65 and N61, constructs a ∼100 pc scale CCC system in the G35 complex.

Toward Early-type Eclipsing Binaries as Extragalactic Milestones: First Calibration of the SBCR from O- and B-type Stars in Detached Eclipsing Binaries

First Author: Taormina, Mónica
Instruments: SOFI, VIRCAM
ProgramIDs: 179.B-2003, 0102.D-0469, 0102.D-0590
BibCode: 2026ApJ..1002L..20T

To measure precise distances beyond the Magellanic Clouds and determine an accurate value of the Hubble constant, eclipsing binary systems composed of early-type stars can play a crucial role. However, it is fundamental to first obtain a reliable empirical surface brightness─color relation (SBCR) for the hottest possible stars. Based on our previous study of six detached eclipsing binaries composed of O- and B-type stars in the Large Magellanic Cloud, we calibrated the SBCR using 12 stars with V − K_s < ─0.6 mag. We found a significant difference between O-type and B-type stars in SBCRs, which are clearly separated in mass. The relation based on B-type stars is consistent with the relation for redder stars from the literature. This allowed us to provide a combined relation valid for stars less massive than ∼16 M_⊙in the wide color range −0.9 < V − K_s < 2.1 mag, with σ = 0.025 mag. Such a relation can provide extragalactic distances precise to as high as ∼1.2% given the sufficient quality and number of target objects. The relation for O-type stars (σ = 0.055 mag) remains uncertain due to its strong dependence on the method used to determine reddening and requires further study. However, we tested it on the only known eclipsing system in M33 and obtained distance modulus DM = 24.90 ± 0.17 mag, which perfectly agrees with the published distance to the system.

Large-scale environments of star-forming active galactic nuclei: How black-hole mass, accretion rate, and luminosity connect to dark-matter halos

First Author: Mountrichas, G.
Instruments: VIMOS
ProgramIDs: 182.A-0886
BibCode: 2026A&A...708A.323M

Understanding the relative roles of large-scale environment and internal host-galaxy processes in shaping active galactic nuclei (AGN) activity is key to constraining models of black-hole growth and galaxy evolution. In this work, we investigated how the environment of X-ray-selected active galactic nuclei (AGNs) relates to black-hole growth and accretion properties, and whether these introduce a dependence on a large-scale environment beyond that set by the host galaxy itself. By combining the XXL and Stripe 82X surveys, we assembled samples of 427 broad-line AGNs at 0.5 < z < 1.2 and over 20 000 galaxies, with host-galaxy properties consistently derived using the same spectral energy distribution fitting methodology and assumptions. Dark-matter halo (DMH) masses were inferred from AGN─galaxy cross-correlation functions, while a multivariate nearest-neighbour matching algorithm was applied to isolate trends with black-hole mass (M_BH), Eddington ratio (λ_Edd), and X-ray luminosity (L_X) under controlled host-galaxy conditions. Within the statistical uncertainties of the present dataset, we find that X-ray AGNs typically reside in halos of log(M_DMH/h⁻¹ M_⊙)≃13, with no significant variation as a function of M_BH, λ_Edd, or L_X. Neither M_BH nor λ_Edd shows a measurable correlation with large-scale environment, which is consistent with a scenario in which long-term black-hole growth and short-term accretion variability are primarily regulated by internal host-galaxy processes rather than halo-scale mass alone. The absence of a statistically significant M_DMH─L_X trend further indicates that AGN radiative output reflects stochastic or feedback-regulated variability, rather than direct modulation by the large-scale environment. Overall, these results support a self-regulated co-evolution framework in which large-scale structure sets the boundary conditions for gas availability and AGN duty cycle, while the subsequent growth and luminosity evolution of AGNs are determined predominantly by local processes within their host galaxies.

A search for optical counterparts in quiescent black hole X-ray transients

First Author: Yanes-Rizo, I. V.
Instruments: FORS2, ULTRACAM_NTT
ProgramIDs: 69.D-0644, 110.24A3, 106.213W
BibCode: 2026A&A...708A.298Y

Dynamical mass measurements of compact stars in X-ray transients demand the detection of optical/near-infrared counterparts in quiescence. Out of the 73 black hole candidates in X-ray transients, optical and near-infrared quiescent counterparts have only been identified for 34 objects. We present ULTRACAM photometric observations of nine candidate black hole X-ray transients with no reported counterparts in quiescence, complemented with data from the public surveys, DECaPS and Pan-STARRS. In addition, we analyze photometry of three sources (SWIFT J1539.2-6227, XTE J1817-330, and XTE J1818-245) obtained during their discovery outburst. The data provide the first optical identifications and precise astrometry of four targets (MAXI J1348-630, SWIFT J1539.2-6227, XTE J1726-476, and XTE J1817-330) plus 3σ lower limits to the quiescent optical magnitudes for an additional five (MAXI J0637-430, 4U 1755-338, MAXI J1803-298, XTE J1818-245, and MAXI J1828-249). Of these five, 4U 1755-338 was found to be active during our ULTRACAM observations, and we used our images to derive refined astrometric coordinates. We used the photometric magnitudes and colors to place preliminary constraints on the orbital periods and spectral types of the companion stars. Finding charts of all the targets are also provided to facilitate future follow-up studies. Finally, we present updated astrometry for XTE J1650-500 using archival FORS2 images.

Constraining small planet compositions for future missions

First Author: Palethorpe, Larissa
Instruments: ESPRESSO, HARPS
ProgramIDs: 0103.C-0289, 098.C-0860
BibCode: 2026MNRAS.548ag520P

Accurate mass and radius measurements of small transiting exoplanets are essential for probing their compositions, formation histories, and potential habitability. We present a uniform analysis of six planetary systems (each hosting at least one small transiting planet): K2-79, K2-106, K2-111, K2-222, K2-263, and TOI-1634. Our study combines new CHEOPS transit observations with archival photometry from K2, TESS, and ground-based facilities, alongside new and archival radial velocity data from HARPS-N, HIRES, ESPRESSO, and others. For each system, we perform joint transit and RV modelling, achieving typical precisions better than 15 per cent and 5 per cent for mass and radius, respectively, and thus enabling precise bulk density determinations. These reveal a range of compositions, including rocky planets near the radius valley (e.g. K2-106 b, TOI-1634 b), intermediate-density planets requiring steam-rich or mixed volatile envelopes (e.g. K2-111 b, K2-263 b), and low-density regimes, consistent with gas dwarfs or water-worlds (e.g. K2-79 b, K2-222 b). Several systems show evidence of additional companions detectable via RVs but not seen in transit. The results highlight the value of coordinated CHEOPS and HARPS-N observations in delivering some of the most precise bulk densities for small planets to date and support the preparation for future atmospheric characterization missions.

Evolution of the early-type fraction in massive galaxies at z < 2: how did early-type morphology form?

First Author: Kajisawa, Masaru
Instruments: VIMOS
ProgramIDs: 1100.A-0949, 194.A-2005, 185.A-0791, 175.A-0839
BibCode: 2026MNRAS.548ag551K

Using James Webb Space Telescope/NIRCam data over a 0.28 deg

$^{2}$

area from COSMOS-Web survey, together with Hubble Space Telescope/Advanced Camera for Surveys data, we investigate early-type fraction of massive galaxies with

$M_{\rm star}\gt 10^{10.5}\,\mathrm{ M}_{\odot }$

$0.2\lt z\lt 2.0$

, and explore the formation of their early-type morphology. We measure concentration index C (

$=R_{80}/R_{20}$

) and asymmetry index A, and select early-type galaxies with

$C\gt C_{n=2.5}$

and

$A_{\rm cor}\lt 0.2$

. Here,

$C_{n=2.5}$

is the concentration expected for a Sérsic profile with

$n=2.5$

under the spatial resolution and depth of the data, and

$A_{\rm cor}$

is the asymmetry corrected for resolution effects. The fraction of early-type galaxies with

$M_{\rm star}\gt 10^{11}\, \mathrm{M}_{\odot }$

(

$=10^{10.5}$

─

$10^{11}\, \mathrm{M}_{\odot }$

) decreases with increasing redshift from

$\sim$

70 per cent (

$\sim$

40─60 per cent) at

$z\sim 0.3$

$\sim $

20─25 per cent (

$\sim$

15─25 per cent) at

$z\sim 1.8$

. We also examine the evolution of their

$R_{20}$

and

$R_{80}$

, which enclose 20 per cent and 80 per cent of the total flux of the galaxy, respectively. The median

$R_{80}$

shows strong mass dependence and significant redshift evolution, whereas the median

$R_{20}$

shows little dependence on either stellar mass or redshift. In contrast, morphological differences are more pronounced in

$R_{20}$

than in

$R_{80}$

: the median

$R_{20}$

of early-type galaxies is smaller than that of late-type and irregular galaxies by 0.25─0.45 and 0.3─0.6 dex, respectively. The median SSFR (specific star formation rate) of sample galaxies strongly correlates with

$R_{20}$

, and early-type galaxies have lower SSFRs by

$\sim 1$

dex. We further find that early-type galaxies at

$z\gtrsim 1.3$

have younger mass-weighted stellar ages of

$t_{\rm mw}\lesssim 2$

Gyr than late-type and irregular ones. Their SSFRs,

$t_{\rm mw}$

, and morphological properties suggest that these high-z early-type galaxies experienced rapid formation of a dense stellar core through starburst, followed by quenching of star formation, and subsequently resumed star formation

$\sim$

1─2 Gyr later.

AGN in massive galaxies identified via optical broad-band variability: lessons from VST-COSMOS for future LSST science

First Author: Bichang'a, B.
Instruments: OMEGACAM
ProgramIDs: 088.D-4013
BibCode: 2026MNRAS.547ag287B

We study the properties of 56 massive (M

$_{\rm {\star }}$

> 10

$^{10}$

$_{\odot }$

) galaxies at

$z\lt 1$

that host AGN, detected via their broad-band optical variability in the VST-COSMOS survey. VST-COSMOS provides a nearly identical single visit depth (r

$\sim$

24.6 mag) and temporal baseline (eleven years) as the forthcoming Legacy Survey of Space and Time (LSST), albeit in a much smaller 1 deg

$^2$

footprint (four orders of magnitude smaller than that of the LSST). We compare the properties (morphologies, the presence of interactions, rest-frame colours and environment) of our AGN to galaxies in a control sample, which are drawn from the non-variable population and matched in redshift and stellar mass to their AGN counterparts. The fraction of AGN with early-type morphology (

$\sim$

55 per cent) and the fraction that is interacting (

$\sim$

23 per cent) are similar to what is observed in the controls, suggesting that these AGN are not primarily triggered by interactions. Similarly, the AGN and controls do not show strong differences in their rest-frame

$(u\!-\!z)$

colours or local environment, suggesting that neither the recent star formation histories nor the surroundings of the AGN are strongly atypical of the general galaxy population. This study provides a glimpse into forthcoming AGN science using the LSST. With vastly improved statistics, LSST will offer unprecedented insights into AGN demographics, host-galaxy evolution and the processes that fuel supermassive black holes, potentially reshaping our understanding of their place in the Universe.

TOI-1080 b: a temperate, rocky planet orbiting a quiet M4V host

First Author: Gómez Maqueo Chew, Y.
Instruments: HARPS, NIRPS
ProgramIDs: 111.254T
BibCode: 2026MNRAS.548ag438G

We present the detection and validation of a small, temperate transiting exoplanet orbiting TOI-1080 every 3.9652482

$_{-0.0000015}^{+0.0000014}$

d. The host is a quiet M4V star at 25.6 pc. The planet signal was first detected by the Transiting Exoplanet Survey Satellite (TESS) and validated using TESS and ground-based observations. By fitting the available light curves, the planet radius is measured to be 1.200

$\pm$

0.058 R

$_{\rm{\oplus }}$

and its equilibrium temperature of

$368_{-10.}^{+12}$

K. With Near Infra Red Planet Searcher (NIRPS) radial velocities, we are able to place a 3

$\sigma$

upper limit on the mass of TOI-1080 b of 10.7 M

$_{\rm{\oplus }}$

. Our injection-recovery tests enable us to discard additional transiting planets in the TOI-1080 system with radii down to 0.9 R

$_{\rm{\oplus }}$

and periods between 0.5 and 7.7 d, and planets with radii larger than 1.4 R

$_{\rm{\oplus }}$

for periods up to 19 d. We demonstrate that it is highly amenable to characterization of its mass and putative atmosphere. In particular, we find that TOI-1080 b is an exceptional target for the ongoing JWST + HST Rocky Worlds DDT programme, having a priority score that is higher than four out of nine targets currently being investigated by the programme. TOI-1080 b can be added to the sample of nearby benchmark planets accessible for detailed study with JWST.

Characterization of Type Ibn Supernovae

First Author: Farias, D.
Instruments: EFOSC2, SOFI
ProgramIDs: 199.D-0143, 1103.D-0328
BibCode: 2026A&A...708A.270F

Context. Type Ibn supernovae (SNe) are characterized by narrow helium (He I) lines from photons produced by the unshocked circumstellar material (CSM). About 80 SNe Ibn have been discovered to date and only a handful of them have extensive observational records. Thus, many open questions remain regarding the progenitor system and the origin of CSM. Aims. Here, we investigate potential correlations between the spectral features of the prominent He I λ5876 Å line and the optical and X-ray light curve properties of Type Ibn SNe (SNe Ibn). Methods. We compiled the largest sample of 61 SNe Ibn to date, of which 24 SNe have photometric and spectroscopic data available from the Young Supernova Experiment and 37 SNe benefit from archival datasets. We fit 24 SNe Ibn with sufficient photometric coverage (B to z bands) using semi-analytical models from MOSFiT. Results. We demonstrate that the light curves of SNe Ibn are more diverse than previous analyses suggest, with absolute r-band peak magnitudes (r_max) of −19.4 ± 0.6 mag, along with rise (from −10 days to peak, γ₋₁₀) and decay rates (from peak to +10 days; γ₊₁₀) of −0.08 ± 0.06 and 0.08 ± 0.03 mag/day, respectively. We find that the majority of SNe Ibn in the subsample are consistent with a low-energy explosion (< 10⁵¹ erg) of a star with a compact envelope surrounded by ~0.1 M_⊙ of helium-rich CSM. The inferred ejecta masses are small (M_ej ~ 1 M_⊙) and expand with a velocity of ~5000 km/s. Our spectroscopic analysis shows that the mean velocity of the narrow component of the He I lines, associated with the CSM, peaks at ~1100 km/s. Conclusions. The mean CSM and ejecta masses inferred for a subsample of SNe Ibn indicate that their progenitors are not massive (~10 M_⊙) single stars at the moment of explosion; rather, they are likely to be binary systems. This finding is in agreement with detections of potential companion stars of SNe Ibn progenitors and inferred CSM properties from stellar evolution models.

Modeling the Break in the Specific Angular Momentum within the Envelope─Disk Transition Zone

First Author: Das, Indrani
Instruments: ALMA_Band_6
ProgramIDs: 2015.1.01415.S, 2013.1.01086.S, 2013.1.00879.S, 2015.1.01512.S, 2017.1.00288.S, 2019.1.00261.L, 2019.A.00034.S
BibCode: 2026ApJ..1001..166D

The observations of protostellar systems show a transition in the radial profile of specific angular momentum (and rotational velocity), as evolving from j∼constant (v_ϕ ∼ r⁻¹) in the infalling-rotating envelope to j ∝ r^1/2 (v_ϕ ∼ r^−1/2) in the Keplerian disk. We employ global MHD disk simulations of gravitational collapse starting from a supercritical prestellar core, that forms a disk and envelope structure in a self-consistent manner, in order to determine the physics of the envelope─disk transition zone (ENDTRANZ). Our results show that the transition from the infalling-rotating envelope to Keplerian disk happens through a jump in the j − r profile, spanning over a finite radial width, which is characterized by the positive local gravitational torques. The outer edge of the ENDTRANZ is identified where the radial infall speed (v_r) begins a sharp decline in magnitude and j begins a transition from j∼constant toward j ∼ r^1/2. Moving radially inward, the centrifugal radius (r_CR) is defined where v_ϕ first transitions to Keplerian velocity at the disk's edge. Farther inward of r_CR, the model disk develops a super-Keplerian rotation due to self-gravity. The inner edge of ENDTRANZ is defined at model centrifugal barrier (r_CB) where v_r drops to negligible values. Inside r_CB, a net negative gravitational torque drives mass accretion onto the protostar. On observational grounds, we identify a jump in the observed j − r profile of class 0/I protostar L1527 IRS for the first time using the ALMA Large Program Early Planet Formation in Embedded Disks (eDisk) data. Comparison with our numerical radial behavior suggests the observed j − r jump serves as a kinematical tracer for the existence of ENDTRANZ. Our results offer insights into the observable imprint of angular momentum redistribution mechanisms during star─disk formation.

CLASH-VLT velocity anisotropy profiles in a stack of massive galaxy clusters

First Author: Maraboli, Enrico
Instruments: MUSE, VIMOS
ProgramIDs: 082.A-0922, 169.A-0595, 186.A-0798, unknownID
BibCode: 2026A&A...708A.264M

We measured the velocity anisotropy profile, β(r), of different galaxy cluster member populations by analysing the stacked projected phase space of nine massive (M_200c > 7 × 10¹⁴ M_⊙) galaxy clusters at intermediate redshifts (0.18 < z < 0.45). We selected our sample of galaxy clusters by choosing the most round and virialised objects among the targets of the CLASH-VLT spectroscopic programme, which offers a large spectral database. Complementary MUSE observations of most of these clusters allowed us to identify an unprecedented number of cluster members, strongly enhancing the precision of our measurement with respect to previous studies. Our sample of cluster members is divided into four classes: the first two are based on colour (red and blue galaxies), and the other two on stellar mass (high and low). To study the velocity anisotropy profile of each cluster-member population, we employed two parallel techniques, namely the MAMPOSSt method (parametric in β(r)) and the inversion of the Jeans equation (non-parametric in β(r)). The results from both techniques are found to be in agreement for any given cluster member population, and suggest that the orbital anisotropy in galaxy clusters grows from the centre (where β ≍ 0.2 − 0.4) to the virial radius (β ≳ 0.8), and it is similar for the different cluster-member populations. We also find an interesting dynamical feature emerging from the Jeans inversion results, that is, a sudden drop in β(r) at a distance of ∼250 kpc from the cluster centre. We provide robust anisotropy estimates from our exploration of a highly significant number of model combinations: 72 with MAMPOSSt (varying the mass, surface number density, β(r) model, and galaxy population) and 18 (varying total mass model and galaxy population) in the Jeans inversion. Such an extensive investigation of the velocity anisotropy profile in galaxy clusters is a wide basis for future studies of cluster dynamical masses and cluster cosmology in the era of large spectroscopic surveys.

LEGA-C stellar population scaling relations: II. Dissecting mass-complete archaeological trends and their evolution since z ∼ 0.7 with LEGA-C and SDSS

First Author: Gallazzi, Anna R.
Instruments: VIMOS
ProgramIDs: 1100.A-0949, 194.A-2005
BibCode: 2026A&A...708A.290G

We analysed a sample of 552 galaxies from the LEGA-C spectroscopic survey (0.6 < z < 0.77), for which we estimated the stellar population parameters by a Bayesian analysis of the stellar absorption features and photometry. We investigated the effect of the current star formation activity on light-weighted mean stellar ages and metallicities and their median trends with stellar mass or velocity dispersion. The bimodality in the global age─mass relation stems from the different age distributions in the quiescent and star-forming populations. No bimodality is observed in the stellar metallicity-mass relation, although quiescent and star-forming galaxies have different distributions in this parameter space. We identified a high-metallicity sequence populated by quiescent and weakly star-forming galaxies. At masses lower than 10^10.8 M_⊙, the median stellar metallicity─mass relation of star-forming galaxies steepens as a consequence of the increasing scatter towards lower stellar metallicities for galaxies with an increasing specific star formation rate at fixed mass. Relying on a consistent analysis of SDSS DR7 spectra and accounting for aperture corrections, we quantified the evolution of the volume-weighted stellar age and stellar metallicity scaling relations between z = 0.7 and the present. We found negligible evolution in the stellar metallicity─mass relation of quiescent galaxies and for M_* > 10¹¹ M_⊙ galaxies in general. Lower-mass star-forming galaxies instead have typically lower metallicities than their local counterparts, indicating significant enrichment since z ∼ 0.7 in the low-mass regime. Notably, the median of the stellar ages of the general population and of quiescent galaxies has changed by only 2 Gyr between z = 0.7 and z = 0.1, which is less than expected from cosmic ageing. Some quiescent galaxies must evolve passively to reach the old boundary of the local population. In order to explain the evolution of the median trends, however, both individual evolution through rejuvenation and/or minor merging that affects the outer galaxy regions and population evolution through quenching of massive metal-rich star-forming galaxies are required.

LEGA-C stellar population scaling relations: I. Chemo-archaeological downsizing trends at z ∼ 0.7

First Author: Gallazzi, Anna R.
Instruments: VIMOS
ProgramIDs: 194.A-2005, 1100.A-0949
BibCode: 2026A&A...708A.289G

We analysed the stellar population properties of a well-defined sample of 552 galaxies at redshift 0.6 < z < 0.77 drawn from the LEGA-C spectroscopic survey. This paper is the first of a series, and it is aimed at (i) presenting the catalogue of revised absorption indices for LEGA-C DR3 and of the inferred physical parameter estimates while describing their systematic uncertainties and at (ii) deriving benchmark scaling relations for the general massive galaxy population at intermediate redshift. We estimated light-weighted mean ages and stellar metallicities through careful analysis of key absorption features in the stellar continuum spectra of the galaxies coupled with photometry. The observables were interpreted in a Bayesian framework with a comprehensive library of model spectra based on stochastic star formation histories, chemical enrichment histories, and dust attenuations. We discuss various sources of systematic uncertainties within our method as well as systematic differences with results from other spectral fitting approaches. We derived volume-weighted scaling relations connecting light-weighted mean ages and stellar metallicities with galaxy stellar mass for the general galaxy population at ⟨z⟩ = 0.7 and masses > 10¹⁰ M_⊙. We find the downsizing trends observed in the local Universe to be already in place 6 Gyr ago. We also observe a bimodal distribution of light-weighted ages as a function of mass, transitioning around 10¹¹ M_⊙. Such a bimodality is not observed in the stellar metallicity-mass relation, which changes from a steep to a flat regime across M_* ∼ 10^10.8 M_⊙. Similar trends in age and metallicity also emerge as a function of velocity dispersion, but with a sharper transition from young to old around log σ_* = 2.3. Differences with respect to the trends as a function of stellar mass suggest that age is primarily dependent on velocity dispersion below and above the transition regime, while both the stellar mass and the depth of the total gravitational potential well (as traced by the velocity dispersion) contribute to stellar metallicity. We release the catalogues of revised absorption index measurements for LEGA-C DR3 used in this work and of the inferred stellar population physical parameters to public repositories.

Pulsar discoveries from the TRAPUM UHF survey of Fermi-LAT sources

First Author: Thongmeearkom, T.
Instruments: ULTRACAM_NTT
ProgramIDs: 110.23W0
BibCode: 2026MNRAS.547ag406T

The Fermi Large Area Telescope (LAT) provides advantages for radio pulsar searches by enabling efficient target selection. We can confidently point radio telescopes to the positions of Fermi unidentified gamma-ray sources that have a high probability of hosting a pulsar. As part of Transients and Pulsars with MeerKAT (TRAPUM), we conducted a survey of Fermi-LAT sources using the Ultra High Frequency (UHF; 544─1088 MHz) receiver of the MeerKAT radio telescope. We observed 79 sources that were identified as pulsar-like candidates using a random forest technique from the Fermi-LAT Fourth Source Catalogue. We observed each target for 10 min at two separate epochs. As a result, we discovered nine new millisecond pulsars (MSPs) and six slow pulsars. Based on the radio discoveries, we also searched for gamma-ray pulsations, confirming that seven of the newly discovered MSPs are associated with Fermi-LAT sources, and performed joint radio and gamma-ray pulsar timing. Companion mass estimates and evidence of radio eclipses indicate that among the nine MSPs there are three black widows and three redbacks. Lastly, we compared the discovered pulsars in the MeerKAT UHF survey against the previous Fermi sources TRAPUM survey at L band, concluding the superiority of UHF observations in sensitivity to fainter pulsars and in detection rate than L band for finding new gamma-ray MSPs.

The Environmental Dependence of Mid-infrared Luminous Dusty Supernovae

First Author: Xiao, Lin
Instruments: MUSE
ProgramIDs: 097.D-0408, 096.D-0263, 097.B-0165, 0103.D-0440, 096.D-0296, 0104.D-0503, 0100.D-0341, 1100.B-0651, 097.D-1054, 0101.C-0329, 096.D-0786, 097.B-0640, 094.B-0298, 0101.D-0748, 095.D-0172, 0100.D-0649, 096.B-0309, 60.A-9301
BibCode: 2026ApJ..1000..296X

Using Spitzer and Wide-field Infrared Survey Explorer images, we have discovered 42 mid-infrared (mid-IR) luminous dusty supernovae (SNe) with local integral field spectroscopy data. The observed mid-IR emission indicates the presence of newly formed dust or preexisting dust heated by radiation from SN or circumstellar medium (CSM) interactions. We carry out a systematic analysis of the SN host environments and their dust properties, to understand the dust-veiled exploding stars and whether such an intense dust production process is associated with their local environments. We find that dusty SNe prefer the locations with higher EW(Hα), lower metallicity, and heavier host extinctions compared to typical SN types, and they show the same increasing sequence in the values of EW(Hα) and oxygen abundance, from hydrogen-rich to type IIn to hydrogen-poor dusty SNe. These differences in the environmental properties of different dusty SN types indicate the diversity of their progenitors. We also find that one marginal correlation is a negative correlation between the SN dust mass and star formation rate. This means that SNe would be more mid-IR-luminous and more dust-rich in regions with lower star formation rates. However, the SN dust mass shows no correlation with the metallicity and the host extinction, which were thought to be key factors affecting the mass-loss history of progenitors and the CSM environment of SNe. Therefore, the dust formation process in SNe might be insensitive to metallicity and the dust conditions of their host environments.

6.7 GHz methanol masers in three high-mass young stellar objects: G37.43+1.51, G37.479─0.105, and G37.55+0.20

First Author: Aberfelds, A.
Instruments: ALMA_Band_3
ProgramIDs: 2015.1.00369.S
BibCode: 2026A&A...708A..73A

Context. Class II 6.7 GHz CH₃OH (methanol) masers are powerful probes of the physical processes in high-mass young stellar objects. We selected three closely located sources from the Irbene single-dish methanol maser monitoring program for high-resolution imaging studies. Aims. Our goal is to investigate their milliarcsecond-scale structure and kinematics to improve our understanding of the physical processes driving maser activity and variability in these sources. Methods. We imaged three sources (G37.43+1.51, G37.479─0.105, and G37.55+0.20) with the European Very Long Baseline Interferometer Network (EVN), supplemented by archival data and single-dish light curves from the Irbene and Ibaraki radio telescopes. Maser emission parameters were derived for all identified cloudlets, and their spatial and kinematic distributions were analyzed. Results. We present the first milliarcsecond-resolution, high-sensitivity images of G37.479─0.105 and G37.55+0.20; other team already studied G37.43+1.51 studied with the EVN. In all three sources, most of the maser cloudlets form linear or arched structures with visible velocity gradients. In G37.43+1.51, two-epoch proper motion measurements reveal a lengthening of one of the maser groups (designated group A), with an expansion velocity of approximately 1.1 km s⁻¹. This is consistent with an overall expansion of the maser region. In G37.479─0.105, 6.7 GHz methanol maser cloudlets are distributed in parabolic structures, with the opening (i.e., the symmetry axis of the parabola) oriented roughly in the same direction as an outflow emanating from the region. This may indicate that the maser cloudlets trace the walls of the outflow cavity. In G37.55+0.20, masers form an elongated structure located at the center of a source of outflows and a formaldehyde maser. The light curve of the periodic maser components and their on-sky distribution suggest substantial differences in line-of-sight distances among cloudlets (assuming the maser pumping conditions are modulated at the speed of light) that appear close in projection. Combined with the position of the continuum maximum, this supports the colliding-wind binary model as the likely driver of maser variability. In all three high-mass protostars, the 6.7 GHz methanol masers appear to trace the innermost regions of the systems they reside in.

MAGAZ3NE: Far-IR and Radio Insights into the Nature and Properties of Ultramassive Galaxies at z ≳ 3

First Author: Chang, Wenjun
Instruments: ALMA_Band_7
ProgramIDs: 2016.1.00463.S, 2015.1.00137.S
BibCode: 2026ApJ..1001..131C

Deep and wide-field near-infrared (NIR) surveys have recently discovered and confirmed ultramassive galaxies (UMGs; log(M⋆/M⊙) > 11) spectroscopically at z ≳ 3. However, most are characterized using only ultraviolet (UV)-to-NIR photometry, offering limited insight into obscured star formation and active galactic nucleus (AGN) activity. In this work, we add 10 far-infrared (FIR)-to-radio passbands to the existing UV-to-NIR catalogs for two spectroscopically confirmed UMGs from the MAGAZ3NE survey, COS-DR3-195616 (z_spec = 3.255) and COS-DR1-209435 (z_spec = 2.481). Utilizing the full UV-to-radio photometry, we revise our earlier UV-NIR-based interpretation of the nature of these galaxies. While both were previously identified as quiescent, our analysis reveals that 195616 is an unobscured galaxy undergoing quenching, and 209435 is a heavily obscured, actively star-forming UMG. We find that 195616 has already depleted most of its molecular gas and is expected to experience minimal future stellar mass growth. In contrast, 209435 contains a substantial molecular gas reservoir and has a prolonged depletion timescale. It is anticipated to increase 0.34 dex in stellar mass, reaching a stellar mass of log(M⋆/M⊙) = 11.72 over the next 0.72 Gyr. We present multipronged evidence for AGN activity in both UMGs. Our findings suggest a scenario where AGN feedback in 195616 may have contributed to gas depletion during quenching, while 209435 remains actively star-forming despite hosting an obscured AGN. Our work shows the importance of FIR-to-radio observations for accurately inferring the nature and properties of galaxies at z ≳ 3.

Unveiling an hourglass-shaped magnetic field toward IRDC G351.77─0.53

First Author: Jadhav, O. R.
Instruments: SHFI
ProgramIDs: 098.F-9306, 097.F-9303, 086.F-9316, 085.F-9323
BibCode: 2026MNRAS.548ag536J

We present the SOFIA/HAWC + 214

$\mu$

m polarimetric observations toward the infrared dark cloud G351.77-0.53 (hereafter G351), complemented by existing multiwavelength data sets. Infrared excess from the embedded sources indicate ongoing star formation activity in the cloud. The G351 cloud hosts two prominent star-forming clumps i.e. c1 and c2. The plane-of-the-sky magnetic field lines from Planck observations are predominantly oriented perpendicular to the filament's major axis. Magnetic field orientations from SOFIA/HAWC + 214

$\mu$

m observations reveal distinct hourglass-shaped field configuration toward c1, while the field lines remain perpendicular to the rest of the filament. Using the Davis-Chandrasekhar-Fermi method, we estimate a mean plane-of-the-sky magnetic field strength of

$\sim$

147

$\pm$

$\mu$

G in the G351 filament, with values reaching

$\sim$

0.8 mG toward c1. The mass-to-flux ratio analysis indicates that the filament is magnetically transcritical, where the gravitational and magnetic field energies are comparable. The hourglass-shaped magnetic field observed toward c1 could result from magnetically regulated gravitational collapse, the alignment of converging sub-filaments with the magnetic field, or a combination of both processes. The energy budget analysis further indicates that magnetic fields play an important role in governing the cloud's gas dynamics, followed by contributions from turbulence and gravity.

The VLT/ERIS grating vector Apodizing Phase Plate coronagraph: Design and on-sky performance

First Author: Kenworthy, M. A.
Instruments: ERIS
ProgramIDs: 112.25QA
BibCode: 2026A&A...708A.239K

Aims. We describe the design, laboratory manufacture, and on-sky testing of the grating vector apodizing phase plate (gvAPP) coronagraph for the Enhanced Resolution Imager and Spectrograph (ERIS) on the Very Large Telescope. Methods. We used both laboratory measurements and on-sky observations to characterise the gvAPP in several different filters, from the K to the L band. Results. In testing, the gvAPP reaches its design specification in the transmission of the optic with 90% in the K bands and 60% in the L band. While the gvAPP reaches its designed raw contrast performance of 1 × 10⁻⁵, it does not reach the post-processed contrast of 5 × 10⁻⁵ in on-sky observations. Electronic detector noise, due to the Airy core of the coronagraphic point spread function inducing cross-talk between the readout amplifiers, produces a repeated pattern within the coronagraphic regions of the gvAPP. Conclusions. Despite these limitations, we recommend the gvAPP as a tool for characterising substellar companions with known separations and position angles, which allow them to be placed in the coronagraphic dark holes for observations. The ERIS gvAPP's leakage term can also be used as a photometric reference for time series observations; however, we caution that the contrast performance may limit such studies to only the brightest targets. ERIS gvAPP data quality may be improved further with better modelling of detector electronic noise. This work is a pathfinder for Extremely Large Telescope instruments including METIS, which will include gvAPP coronagraphs with improved designs based on these results.

First statistical constraints on galactic-scale outflow properties traced by their extended Mg II emission with MUSE

First Author: Pessa, Ismael
Instruments: MUSE
ProgramIDs: 1104.A-0026
BibCode: 2026A&A...708A.214P

Galaxies evolve within vast gaseous halos that fuel star formation and carry signatures of feedback-driven outflows. Deep integral field data have enabled the study of Mg IIλλ2796, 2803 halos, which trace galaxy-scale outflows in emission, and while individual detections of Mg II halos have revealed extended circumgalactic structures, their faintness has limited studies to single-object analyses. Here, we present the first statistical study of Mg II-emitting halos using deep MUSE observations of 47 star-forming galaxies at 0.7 < z < 2.0. Building on our previous work, where we developed and applied an outflow modeling framework to a single Mg II halo, we now extend this approach to a larger sample, enabling robust population-level insights into the properties of circumgalactic outflows traced by their extended Mg II emission for the first time. We detected extended Mg II emission out to tens of kiloparsecs and modeled the outflows as an ensemble of radially accelerating shells. Galaxies with Mg II outflows tend to have higher star formation rates (SFRs) and specific star formation rates (sSFRs) and younger stellar populations─consistent with star-formation-driven winds. The observations are consistent with winds that accelerate linearly with radius (v ∝ r) from launching velocities of v ∼ 60 km s⁻¹ up to maximum velocities that correlate with the stellar mass of galaxies, and are of about ∼490 km s⁻¹. The inner regions of the outflows are highly opaque (log τ ∼ 2.6), and we also identify a tentative trend between stellar mass and central optical depth. The opening angle of the outflow shows some dependency on the host-galaxy stellar mass, with less massive galaxies showing primarily wide opening angles (i.e., nearly isotropic outflows), and more massive galaxies showing a broader range of values, with both wide and narrow opening angles. The distribution of the spatial extent of Mg II halos exhibits a clear peak at half-light radius (HLR) of ∼5 kpc, with an extended tail of larger HLR values, up to ∼20 kpc. Compact halo sizes (HLR < 8 kpc) correlate with stellar mass, but extended halos do not, which could suggest a difference in the powering mechanism between compact and extended halos. This work provides new insight into the structure and dynamics of the circumgalactic medium and its role in galaxy evolution by constraining, for the first time, the properties of circumgalactic outflows with a statistically significant sample of galaxies with an extended Mg II emission halo.

Photometric masses for long period CVs: the case study of CSS131106

First Author: Das, M.
Instruments: ULTRACAM_NTT
ProgramIDs: unknownID
BibCode: 2026MNRAS.548ag549D

We present high-speed photometry of the eclipsing cataclysmic variable CSS131106 J052412+004148. We determine the system parameters by modelling the eclipse light curve using the photometric eclipse method, in which the mass ratio is determined from the relative timings of the white dwarf and bright spot eclipses. Despite the blended white dwarf and bright spot ingress, typical of longer period cataclysmic variables, we perform simulations that show we are able to reliably constrain the component masses. We find a mass ratio of

$q = 0.81 \pm 0.06$

and inclination

$i = 78.5 \pm 0.7$

degrees. The white dwarf and donor masses were found to be

$M_{w} = 0.72 \pm 0.04$

${\rm M}_{\odot }$

and

$M_{d} = 0.58 \pm 0.06$

${\rm M}_{\odot }$

respectively. The white dwarf temperature was estimated to be

$T_{\rm eff} = 18~500 \pm 2000$

K, implying a moderate accretion rate of

$\dot{M} = 3 \pm 1 \times 10^{-10}$

${\rm M}_{\odot }$

$^{-1}$

. The donor in CSS131106 J052412+004148 joins two other long-period cataclysmic variables (IP Peg and HS 0220+0031) in being unusually small for its mass, even when compared to detached M-dwarfs. The donors in all three systems are also unusually cool for their mass. We discuss possible explanations for the small radii and cool temperatures of the donors in these systems, but find no viable explanation for their properties.

Hot subdwarf stars from the Hamburg Quasar Survey

First Author: Heber, U.
Instruments: UVES
ProgramIDs: 165.H-0588, 167.D-0407, 70.D-0334, 71.D-0383
BibCode: 2026A&A...708A.115H

Hot subluminous stars (subdwarf B&O; sdB, sdO) are evolved low mass stars originating from red giants that lost their envelope almost entirely. The multitude of observed phenomena imply that several pathways may form hot subdwarfs, most involving close binary channels. The Hamburg Quasar Survey (HQS) has led to the discovery of many faint blue stars, including hot subdwarf stars. Many of the HQS-sdB stars have been studied in detail, but analyses of the helium-rich sdOB and sdO stars are lacking. The recent development of model spectra calulated from model atmopheres in local thermodynamic equilibrium (LTE) allowing for non-LTE departures (hybrid LTE/NLTE model spectra, the 2^nd generation Bamberg model grids) enables us to improve the spectroscopic analyses of sdB stars as well as of the previously unstudied sdO stars allowing precise atmospheric parameters to be derived, while consistently accounting for parameter correlations and systematic uncertainties. The Gaia mission provided astrometric data of unprecedented quality, which allow fundamental stellar parameters to be derived from atmospheric parameters via parallax measurements. We used spectral energy distributions to identify composite-colour sdB binaries and present the result of detailed spectroscopic analyses of 122 non-composite subdwarfs from the HQS to identify potential evolutionary pathways. Comparison to evolutionary tracks both in the Kiel (T_eff-log g) and the physical Hertzsprung─Russell (T_eff─logL) diagram finds the location of the sdB stars on the extreme horizontal branch (EHB). Their derived mass distribution and median mass of 0.45 M_⊙ are consistent with the canonical EHB mass. We revisited the sample of known pulsating HQS-sdB stars and find no significant differences between their mass distributions and those of sdB stars that do not pulsate. The helium-rich sdOB and sdO stars are found near the helium main sequence (He-MS). The derived mass distribution of the extremely He-rich subdwarfs is broader (0.48─1.05 M_⊙) and peaks at a median of 0.70 M_⊙, significantly larger than those of the hydrogen-rich stars. Intermediate He-rich subdwarfs are also He-MS stars, but of lower mass (0.55 M_⊙) than the extremely He-rich subdwarfs. This strongly supports the merger scenario for the origin of He-rich sdO stars, in which two helium white dwarfs merge following orbital decay driven by gravitational-wave emission, producing a He-rich sdO or sdOB star. Comparing results from similar studies, we speculate that older populations produce more massive helium white dwarfs mergers.

GALACTICNUCLEUS: A high-angular-resolution JHKs imaging survey of the Galactic center: V. Toward the GNS second data release: Methodology and photometric and astrometric performance

First Author: Martínez-Arranz, Á.
Instruments: HAWKI
ProgramIDs: 195.B-0283
BibCode: 2026A&A...708A..58M

Context. The center of the Milky Way presents a unique environment of fundamental astrophysical interest. However, its extreme crowding and extinction make this region particularly challenging to study. The GALACTICNUCLEUS survey, a high-angularresolution near-infrared imaging program, was designed to overcome these difficulties. Its first data release provides a powerful resource for exploring the Galactic center and enables key discoveries in this extreme environment. Aims. We present the methodology and first results of a second data release of the GALACTICNUCLEUS survey, which incorporates significant improvements in data reduction, calibration, and methodology as well as a second epoch. In particular, we aim to provide deeper photometry, improved astrometry, and high-precision proper motion for the test fields analyzed in this study. Methods. Observations were obtained with VLT/HAWK-I over two epochs separated by approximately seven years for most pointings and by four to five years for others. The data were acquired using speckle holography, and in the case of the second epoch, a ground-layer adaptive optics system was also employed. We have developed a new reduction pipeline with key improvements, including enhanced distortion corrections and jackknife-based error estimation. For the test fields presented in this work, proper motions were derived using two complementary approaches: (i) relative proper motions, aligning epochs within the survey itself, and (ii) absolute proper motions, tied to the Gaia reference frame. Validation was performed on two representative test fields: one in the Galactic bar and one in the crowded nuclear stellar disk, overlapping with the Arches cluster. Results. For the fields analyzed in this pilot study, the new release achieves photometry that is about 1 mag deeper and astrometry roughly five times more precise than the first data release. Proper motions reach an accuracy of ∼0.5 mas yr⁻¹ relative to Gaia despite being based solely on two ground-based epochs. Both relative and absolute approaches deliver consistent results. In the Arches field, we recovered the cluster with mean velocities consistent with previous HST-based studies. The proper-motion distributions reveal distinct kinematic behavior between the bulge and nuclear stellar disk fields, suggesting that the latter constitutes a dynamically distinct component. Comparisons with previous catalogs confirmed the robustness of our methodology. Conclusions. The data analyzed in this study provide ground-based proper motions measurements of the Galactic center that are among the most precise currently available for bright stars and that stand out among other ground-based catalogs at red clump and fainter magnitudes. In this pilot analysis, the proper-motion distributions already reveal a distinct kinematic behavior between the bulge and nuclear stellar disk fields. Once the full survey has been analyzed, it will enable detailed studies of the structure and dynamics of the nuclear stellar disk. The expected quality of the final catalogs will also make them well suited for combination with observations from space-based missions, such as JWST and the Roman Space Telescope.

A method to derive self-consistent NLTE astrophysical parameters for four million high-resolution 4MOST stellar spectra in half a day with invertible neural networks

First Author: Ksoll, Victor F.
Instruments: UVES
ProgramIDs: 71.D-0370, 68.C-0548, 65.L-0507, 273.D-5032, 165.N-0276, 266.D-5655
BibCode: 2026A&A...708A.118K

Context. Modern spectroscopic surveys have the capacity to obtain the spectra of millions of stars. However, classical spectroscopic methods can often be computationally expensive, rendering them impractical for the analysis of large datasets. Aims. We introduce a novel simulation-based, deep-learning approach for the efficient analysis of high-resolution stellar spectra that will be obtained with the upcoming high-resolution 4MOST spectrograph. Methods. We used a suite of synthetic non-local thermodynamic equilibrium (NLTE) spectra generated with Turbospectrum to mimic 4MOST observations and trained a conditional invertible neural network (cINN) for the purpose of predicting self-consistently stellar surface parameters and chemical abundances. The cINN is a neural network architecture that estimates full posterior distributions for the target stellar properties, providing an intrinsic uncertainty estimate. We evaluated the predictive performance of the trained cINN model on both synthetic data and the observed spectra of stars. Results. We found that our new cINN trained on NLTE synthetic spectra is capable of recovering stellar parameters with average errors (σ) of 33 K for T_eff, 0.16 dex for log (g), and 0.12 dex for [Fe/H], 0.1 dex for [Ca/Fe], 0.11 for [Mg/Fe], and 0.51 dex for [Li/Fe], respectively, at a signal-to-noise ratio (S/N) of 250 per Angstrom. From the analysis of the observed spectra of Gaia-ESO/4MOST/PLATO benchmark stars, we verified that our NLTE estimates for stellar parameters and abundances are consistent with results obtained with the independent code TSFitPy. We conclude that the NLTE cINN is robust and that it can, in theory, evaluate four million high-resolution 4MOST spectra in less than a day, using GPU acceleration.

Physical properties of accessible Near Earth Objects, including the primitive (68278) 2001 FC7

First Author: Fornasier, Sonia
Instruments: EMMI
ProgramIDs: 076.C-0577
BibCode: 2026Icar..45317072F

We used the Spitzer Space Telescope to carry out infrared spectroscopy (between 5.2 and 38μm) of nine Near Earth Objects: (2063) Bacchus, (6239) Minos, (11284) Belenus, (17511) 1992 QN, (18109) 2000 NG11, (67367) 2000 LY27, (68278) 2001 FC7, (68359) 2001 OZ13 and (136618) 1994 CN2. These objects were selected because they are among the most accessible for a space mission in terms of ∆V. Our aim was to determine their size and albedo, and to constrain their surface composition. The data were processed using the Spitzer pipeline. We modeled the asteroids' spectral energy distribution using the Near Earth Asteroid Thermal Model to determine their sizes and albedos. We complemented emissivity spectra with visible and near-infrared (VNIR) spectroscopic data from the literature to infer taxonomic classes and meteorite analogs. Photometric observations of eight NEOs, including four Spitzer targets plus (3361) Orpheus, (7088) Ishtar, (8035) 1992 TB, and (54071) 20000 GQ146, were also carried out at the New Technology Telescope to determine their absolute magnitude and visible colors. The selected targets have diameters ranging from 0.5 to 1.6 km. Five of the objects in our sample are S-complex or Q-type near-Earth objects (Bacchus, Minos, Belenus, 2001 OZ13 and 1994 CN2), with albedos ranging from 20% to 39%. Their VNIR and emissivity spectra indicate similarities with ordinary chondrites, suggesting silicaceous-rich composition. Three other targets belong to the X-complex (1992 QN, 2000 NG11 and possibly 2000 LY27), with albedos ranging from 15% to 33% for 1992 QN, which is likely to be an Xe-type object. 2001 FC7 is the largest NEO in the sample studied here (diameter = 1.6 km), the darkest (albedo 3.2 ± 0.03%), the most accessible (∆V=5.05 km s⁻¹) for a space mission, and its emissivity and VNIR spectrum is best matched by carbonaceous chondrites, indicating a very primordial surface composition.

Chemical tagging with APOGEE, Gaia, MUSE, and HST: constraints on the formation of ω Centauri

First Author: Mason, Andrew C.
Instruments: MUSE
ProgramIDs: 105.20CG
BibCode: 2026MNRAS.547ag433M

Current evidence suggests that

$\omega$

Cen is the nuclear star cluster of a galaxy that merged with the Milky Way at early times. We use Apache Point Observatory Galactic Evolution Experiment (APOGEE), Gaia, Multi Unit Spectroscopic Explorer, and Hubble Space Telescope data supplemented by galaxy chemical evolution models to place constraints on the assembly and chemical enrichment history of

$\omega$

Cen. The APOGEE data reveal three stellar populations occupying separate loci on canonical chemical planes. One population resembles metal-poor halo field stars (P1), a second shows light-element abundance anticorrelations typical of metal-poor globular clusters (IM), and a third population (P2) is characterized by an extreme 'second-generation' abundance pattern. Both P1 and P2 populations cover a broad range of metallicity, consistent with extended histories of bursty star formation (SF), which is also evident from their light and

$\alpha$

-element abundance patterns. Conversely, the IM stars exhibit a narrow metallicity spread, combined with Al─Mg, Na─O, and C─N anticorrelations resembling metal-poor Galactic globular clusters. Moreover, these three populations alone seem to account for the distribution of

$\omega$

Cen stars in the chromosome map. We discuss these findings in the context of a scenario according to which

$\omega$

Cen formed by a combination of in situ SF within the host galaxy (P1), followed by the spiralling in of gas-rich globular clusters (IM), leading to another burst of SF (P2). We perform a robust comparison of the chemical composition of

$\omega$

Cen with those of halo substructures well represented in APOGEE DR17, finding no chemical associations to a high confidence level.

The Next Generation Fornax Survey (NGFS): VIII. A support vector machine approach to disentangling globular clusters

First Author: Ordenes-Briceno, Yasna
Instruments: VIRCAM
ProgramIDs: 090.B-0477, 092.B-0622
BibCode: 2026A&A...706A.368O

Context. Wide-field, multiband surveys are capable of detecting millions of unresolved sources in nearby galaxy clusters; however, separating globular clusters (GCs) from foreground stars and background galaxies remains challenging. Scalable and automated classification methods are therefore essential to transform forthcoming data from facilities such as the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST), Euclid, and the Nancy Grace Roman Space Telescope into robust constraints on galaxy assembly. Aims. We present a supervised machine-learning method to separate GCs, stars, and galaxies using their distribution in color-color space. The primary objective is to recover a clean and reliable GC sample optimized for next-generation survey volumes. Methods. We analyzed the central 3 deg² of the Next Generation Fornax Survey (NGFS), which images the Fornax cluster in u'g'i' (BLANCO/DECam) and JK_s (VISTA/VIRCAM). We trained a support vector machine (SVM; svm.SVC implemented in scikit-learn) using spectroscopically confirmed sources. The initial model employed 15 features, including all color combinations from u'g'i'JK_s and basic morphological parameters (e.g., FWHM and ellipticity). Results. Color combinations linking near-ultraviolet (NUV) and optical to near-infrared (NIR) wavelengths, particularly (u'−g') versus (g'−K_s), provide the strongest discrimination among object classes. The full 15-feature model achieves an accuracy of 97.3%. A reduced seven-feature model, built from the most informative and least correlated features, attains a 96.6% level of accuracy with a misclassification rate of 10.4%, offering a more efficient and robust solution. Excluding the u' or NIR bands significantly degrades performance. Tests using LSST-like filters, constructed from NGFS u'g'i' and Dark Energy Survey r'z'Y data, show that the u' and Y bands are essential, although models lacking NIR coverage remain suboptimal. Conclusions. Broad spectral energy distribution coverage combined with simple morphological parameters enables an accurate and scalable classification of unresolved sources. The inclusion of NIR data substantially improves GC identification and the joint exploitation of LSST with Euclid and Roman observations will further enhance machine-learning approaches in large extragalactic surveys.

Insights into Jet-induced Cloud Disruption in NGC 1316: ALMA Reveals Spatially Extended Molecular Gas

First Author: Morokuma-Matsui, Kana
Instruments: ALMA_Band_3, ALMA_Band_6, ALMA_Band_7
ProgramIDs: 2017.1.00129.S, 2017.1.01140.S, 2019.1.01845.S
BibCode: 2026ApJ..1007....3M

We present Atacama Large Millimeter/submillimeter Array (ALMA) CO(J = 1−0) observations of a nearby radio galaxy, NGC 1316, at 100 pc resolution to investigate the impact of active galactic nucleus (AGN) jets on the molecular gas. The molecular gas exhibits complex spatial and kinematic distributions, with broad CO line widths (>50 km s⁻¹) observed in several regions. The interferometric CO flux is only 34%─38% compared to single-dish data, indicating a large fraction of spatially extended molecular gas, especially in the central regions. We identified 24 giant molecular cloud associations (GMAs) primarily within the "NW Shell" and the "SE Blob"; these GMAs show velocity dispersions approximately twice as high as those in typical star-forming galaxies for their sizes. Analysis of archival ALMA CO(J = 2−1) and CO(J = 3−2) data reveals elevated line ratios (R₂₁ ∼ 1 and R₃₁ ∼ 1) in gas near the jet but, away from the jet, typical values (R₂₁ ∼ 0.7, R₃₁ ∼ 0.3). A multiwavelength comparison reveals a ∼5 kpc warm ionized gas shell that encompasses the molecular NW Shell. The observed energetics and bubble morphology are consistent with an expanding bubble model driven by the jet assuming a jet power of 1.6 × 10⁴³ erg s⁻¹. We propose that the high extended gas fraction results from the destruction of molecular clouds due to interactions with the jet plasma. NGC 1316 may be a good example of jet-induced negative feedback through the ablation, dispersal, and rarification of dense molecular clouds through jet─interstellar medium interactions.

Investigating the role of turbulence in the interstellar medium in z ∼ 3 dusty star-forming galaxies using kpc-resolution ALMA dust and gas maps

First Author: Westoby, B. A.
Instruments: ALMA_Band_3, ALMA_Band_4, ALMA_Band_7
ProgramIDs: 2012.1.00307.S, 2016.1.00048.S, 2017.1.01163.S, 2019.1.00771.S, 2022.1.00955.S
BibCode: 2026MNRAS.550g1274W

We present ALMA high-resolution (

$\sim 0.25 \, \mathrm{ arcsec}/2\, \rm {kpc}$

) CO(5─4) and CO(4─3) observations of three

$z\sim 3$

submillimetre-selected dusty galaxies from the ALESS survey. These data complement existing (sub)-kpc scale ALMA 870 μm continuum imaging and JWST NIRCam and MIRI imaging from the ALESS-JWST program, allowing us to trace the molecular gas, dust-obscured star formation, and stellar populations on similar spatial scales. We spectroscopically confirm that two of the sources lie at the same redshift and are likely interacting. We find that the molecular-gas distribution broadly follows the dusty star-forming structures seen in the 870 μm dust continuum imaging, but that the gas reservoirs are significantly more extended than the dust emission with a spatial extent comparable to the rest-frame near-infrared stellar emission. By modelling the kinematics for the two highest signal-to-noise sources, we find that the galaxies are well-fit by rotating disc models with high ratios of ordered-to-random motion (

$V_{\rm {max}}\, /\, \overline{\sigma }=5\pm 1$

and

$6\pm 1$

), although smaller-scale kinematic deviations cannot be ruled out at the current sensitivity and spatial resolution. Finally, utilizing the high-resolution 870 μm dust continuum and CO data, we investigate star formation scaling relations on kpc-scales in these high-redshift galaxies. Assuming a constant CO-to-H

$_{2}$

conversion factor and excitation ratio, we find that the data are offset from theoretical star formation relation predictions that do not take turbulence into account, but consistent with gravo-turbulent models, thereby suggesting that turbulence plays a central role in regulating star formation at high redshift.

A faint M_UV = −14.5 Lyman-continuum leaker candidate in the epoch of reionization: Unprecedented Lyα properties at z = 5.725

First Author: Messa, M.
Instruments: XSHOOTER
ProgramIDs: 115.29G6
BibCode: 2026A&A...708L...2M

We report the unprecedented Lyα properties of AMORE6, an extremely metal-poor (12 + log(O/H) < 6), low-mass (M_★ = 4.4 × 10⁵ M_⊙), and ultracompact (effective radius ∼30 pc) dwarf galaxy at z = 5.7253, which is gravitationally lensed by the cluster A2744. A prominent, narrow, and nearly symmetric Lyα emission line is detected at the systemic redshift (the latter traced by Hβ, from JWST/NIRCam slitless spectroscopy), with a rest-frame equivalent width of 150 ± 10 Å, a full width at half maximum of 58 ± 1 km s⁻¹, and a slight asymmetry, resulting in a flux excess of ∼10% in the red wing of the line. The negligible velocity offset from systemic (dv = 4 ± 67 km s⁻¹, 3σ uncertainty), together with the sharpness and symmetry of the profile, indicates minimum radiative transfer effects, which implies a neutral hydrogen column density consistent with an optically thin medium that in turn is compatible with a nonzero ionizing photon escape fraction. If indirect spectral diagnostics calibrated at z < 4.5 remain the only viable tools for identifying LyC leakers during reionization, then based on its strongest indicator (Lyα), AMORE6 stands out as one of the most compelling LyC-leaking candidates yet discovered in the epoch of reionization.

The dispersed matter planet project sample ─ detection limits, occurrence rates, and new planets

First Author: Standing, Matthew R.
Instruments: ESPRESSO, HARPS, XSHOOTER
ProgramIDs: 0100.C-0097, 112.25LZ, 107.22UN, 196.C-1006, 183.C-0972, 106.21R4, 0102.C-0558, 098.C-0366, 096.C-0876, 095.C-0799, 096.C-0460, 092.C-0721, 093.C-0409, 089.C-0497, 091.C-0866, 090.C-0421, 087.C-0531, 088.C-0662, 099.C-0798, 0100.C-0836, 072.C-0488, 077.C-0364, 079.C-0927, 081.C-0148, 085.C-0019, 087.C-0368, 098.C-0269, 097.C-0390, 096.C-0499, 089.C-0732, 108.222V, 091.C-0936, 0103.C-0432, 095.C-0551, 110.248C, 099.C-0458
BibCode: 2026MNRAS.547ag370S

Dispersed matter planet project (DMPP) is a radial velocity survey that aims to detect planets around stars exhibiting anomalous activity signatures, consistent with the presence of close-in evaporating planets. Here, we report the discovery of seven new planetary signals in five different systems: DMPP-2 c & d, HD 67200/DMPP-6 b & c, HD 118006/DMPP-7 b, HD 191122/DMPP-8 b, and HD 200133/DMPP-9 b. We update the orbital parameters of the DMPP-1, DMPP-2, and DMPP-3 systems, along with those of the planetary systems orbiting HD 181433, HD 39194, and HD 89839. We derive detection limits for all 24 targets in our sample with adequate observational coverage, and test the DMPP hypothesis by calculating the occurrence rates for planets in this configuration. We find that the occurrence rates of planets in our sample with orbital periods shorter than

$50 \mathrm{d}$

and masses in the range 3─10 M

$_{\rm{\oplus }}$

are

$83.0^{+27.1}_{-24.4} \,\rm per\,cent$

, for 10─30 M

$_{\rm{\oplus }}$

are

$27.0^{+15.0}_{-11.2} \,\rm per\,cent$

, and for 30─100 M

$_{\rm{\oplus }}$

are

$13.9^{+11.8}_{-7.5} \,\rm per\,cent$

. This is significantly higher than the occurrence rates reported by other radial velocity surveys, providing strong support for the DMPP hypothesis.

The supersonic nature of jellyfish galaxies

First Author: Ignesti, Alessandro
Instruments: MUSE
ProgramIDs: 196.B-0578
BibCode: 2026A&A...708A..65I

All gas-rich galaxies in cluster environments are expected to experience ram-pressure stripping from the intracluster medium. However, only a fraction of these develop ongoing star formation in their stripped tail, becoming the so-called jellyfish galaxies. In this work we provide observational evidence that magnetic fields can signal differences in extraplanar star formation, and we explore the physical conditions that lead to the formation of a jellyfish galaxy. We first focus on JO147, a jellyfish galaxy that features weak star formation activity in its tail. Using MeerKAT radio continuum observations, we discovered polarized emission only in a small fraction of its tail, with an average fraction of 10%, and a low Mach number, ℳ = 1.3 − 1.6, suggesting a possible association between magnetic field draping, shock compression of the gas, and extraplanar star formation activity. We then tested this scenario in a sample of 17 jellyfish galaxies from the GASP project. We combined dynamical models for their orbits within the host clusters with realistic cluster temperature profiles to infer their Mach number, and we found a positive correlation between it and the star formation activity in their tail. We conclude that supersonic motion is a necessary condition for triggering star formation in the stripped tails of jellyfish galaxies. Our findings provide empirical evidence that the critical factor preventing evaporation of the stripped gas is the shock compression induced by the supersonic motion through the cluster. This process likely enhances the magnetic field surrounding the galaxy and the properties of the stripped material.

Unveiling blazar candidates within unassociated Fermi sources through radio and near-infrared observations

First Author: Martínez, C. I.
Instruments: VIRCAM
ProgramIDs: 179.B-2002
BibCode: 2026A&A...708A..52M

Context. The Fermi Large Area Telescope (LAT) detected 7195 γ-ray sources within the first 12 years of scientific observations, spanning an energy range from 50 MeV to 1 TeV. The fourth source catalog 4FGL-DR4 (Fermi Gamma-ray LAT Data Release 4), contains 2423 unassociated γ-ray sources (UGSs). This catalog provides an excellent opportunity to explore the scientific potential of these high-energy targets and to identify their counterparts at different wavelengths. Aims. We identified blazar candidates as counterparts to UGSs in the Galactic plane through a multiwavelength analysis of near-infrared and radio observations. Methods. We compiled an initial list of 318 non-extended Fermi sources located in the Galactic plane. After filtering the list based on interstellar extinction and the 95% confidence Fermi error ellipse, we selected 22 UGS for evaluation. We searched the Very Large Array Sky Survey (VLASS) catalog for sources of continuum radio emission near each target on the sample list. We identified a total of 34 radio sources as potential counterparts to the 22 UGSs within the Fermi error ellipses. We confirmed these radio sources as blazar candidates by analyzing their associated near-infrared sources using the color-magnitude diagram (CMD), color-color diagram (CCD), and K_s-band variability from the VISTA Variables in the Via Lactea (VVV) catalog. Additionally, we examined the radio spectral energy distribution (SED) using observations from the Rapid ASKAP Continuum Survey (RACS). Results. We found evidence for the association of five UGSs: four with blazar candidates and one with an elliptical galaxy. Additionally, we estimated its SED using RACS bands.

N-emitters as possible signposts of globular cluster formation

First Author: Schaerer, D.
Instruments: VIMOS
ProgramIDs: 194.A-2003
BibCode: 2026A&A...708A..49S

Based on the unusual chemical abundance ratios of N-emitters, which resemble those of globular cluster (GC) stars, their compactness, high interstellar medium (ISM) densities, and other properties, it has been suggested that N-emitters could indicate the formation sites of globulars. A recent statistical study of the N-emitter population has quantified the frequency f_N of these rare objects and their redshift evolution (Morel et al. 2025, A&A, submitted, [arXiv:2511.20484]). Using these results, we tested whether N-emitters trace the formation of GCs and used the observed cosmic star formation rate density evolution to predict the cosmological evolution of the GC population with time, their age distribution, and the total present-day stellar mass density formed in globulars. The predicted age distribution of GCs strongly resembles the typical asymmetric observed distributions in the Galaxy and ellipiticals, with a peak at ∼11.5─12 Gyr and a longer tail extending to younger ages. We derive a total stellar mass density formed in N-emitters down to redshift zero of (2 − 4)×10⁵ M_⊙ Mpc⁻³, which matches within a factor of ∼2 the observed fraction of stellar mass found in the GC population at z = 0. These results provide additional indirect arguments supporting that N-emitters could represent signposts of a short phase of GC formation.

An equal mass ratio supermassive binary black holes in Q J0158−4325 with periodic microlensing signature?

First Author: Yan, Changshuo
Instruments: XSHOOTER
ProgramIDs: 0103.B-0566
BibCode: 2026MNRAS.547ag402Y

This study aims to test whether a supermassive binary black hole (SMBBH) system with a triple-disc accretion structure can explain the observed

$\sim$

173-d periodic microlensing variations and spectral energy distribution (SED) of the gravitationally lensed quasar Q J0158−4325. We construct a triple-disc model for the SMBBH system, incorporating realistic accretion disc structures, orbital motion, and microlensing effects. The model is used to simulate optical and X-ray microlensing light curves and SEDs, which are compared with long-term optical monitoring, X-ray observations, and ultraviolet (UV)─optical spectra from the Hubble Space Telescope and XSHOOTER. Bayesian analysis and Markov chain Monte Carlo fitting are applied to constrain model parameters. The model successfully reproduces the periodic microlensing variations. Combined light curve and SED fitting favour a high mass ratio (

$q\gt 0.5$

) SMBBH system with total mass

${\sim} 10^{9.5} \, {\rm M}_\odot$

, and nearly equal-mass binaries (

$q\sim 1$

) provide the best agreement with both the optical/UV spectrum and the microlensing signal. This model predicts larger X-ray microlensing amplitudes than in the optical, but the available X-ray observations lack the precision needed to place strong constraints. We emphasize the need for future high-cadence monitoring to resolve remaining uncertainties. This study demonstrates the effectiveness of combining multiwavelength microlensing signatures with spectral modelling to provide robust constraints on SMBBH systems, with the developed framework applicable to other lensed quasars for identifying and characterizing candidate SMBBHs.

The JWST EXCELS Survey: Insights into the Nature of Quenching at Cosmic Noon

First Author: Skarbinski, Maya
Instruments: VIMOS
ProgramIDs: 194.A-2003
BibCode: 2026ApJ..1000..191S

We study 24 massive quiescent galaxies with logM*/M⊙>10 at 1 < z < 3 with JWST/NIRSpec medium-resolution observations from the Early Extragalactic Continuum and Emission Line Survey (EXCELS). We reconstruct their star formation histories and find that they have large bursts (100─1000 M_⊙ yr⁻¹), followed by a rapid truncation of star formation. The number densities of the quenched galaxies in our sample that we predict underwent a submillimeter phase are consistent with submillimeter galaxies being the progenitors of our quenched population. The median post-starburst visibility time is ∼600 Myr, with more massive galaxies ( logM*/M⊙>10.7 ) exhibiting shorter visibility times than lower-mass galaxies. The range of quenching times—defined as the time from the peak starburst to the time of quiescence—found in this sample (0.06─1.75 Gyr) suggests multiple quenching pathways, consistent with previous studies. We do not see evidence for quenching mechanisms varying with redshift between 1 < z < 3. We detect evidence for weak active galactic nucleus activity in four out of the eight galaxies with robust emission line detections, based on line ratio diagnostics. Our findings suggest that there is a diverse range of quenching mechanisms at Cosmic Noon, and support a scenario in which the primary quenching mechanisms are rapid (<500 Myr) following a starburst.

PRIMER and JADES reveal an abundance of massive quiescent galaxies at 2 < z < 5

First Author: Stevenson, Struan D.
Instruments: ALMA_Band_3, ALMA_Band_4, ALMA_Band_6, ALMA_Band_7, ALMA_Band_8, ALMA_Band_9
ProgramIDs: 2011.0.00064.S, 2011.0.00097.S, 2011.0.00539.S, 2011.0.00742.S, 2012.1.00076.S, 2012.1.00323.S, 2012.1.00523.S, 2012.1.00536.S, 2012.1.00919.S, 2012.1.00952.S, 2012.1.00978.S, 2013.1.00034.S, 2013.1.00092.S, 2013.1.00118.S, 2013.1.00151.S, 2013.1.00171.S, 2013.1.00208.S, 2013.1.00276.S, 2013.1.00668.S, 2013.1.00815.S, 2013.1.00884.S, 2013.1.00914.S, 2013.1.01258.S, 2013.1.01292.S, 2015.1.00026.S, 2015.1.00055.S, 2015.1.00122.S, 2015.1.00137.S, 2015.1.00260.S, 2015.1.00299.S, 2015.1.00379.S, 2015.1.00388.S, 2015.1.00540.S, 2015.1.00568.S, 2015.1.00664.S, 2015.1.00704.S, 2015.1.00853.S, 2015.1.00861.S, 2015.1.00862.S, 2015.1.00928.S, 2015.1.01074.S, 2015.1.01105.S, 2015.1.01111.S, 2015.1.01171.S, 2015.1.01212.S, 2015.1.01495.S, 2015.1.01590.S, 2015.A.00026.S, 2016.1.00478.S, 2016.1.00624.S, 2016.1.00735.S, 2016.1.01208.S
BibCode: 2026MNRAS.545f2087S

We select a mass-complete sample of 225 quiescent galaxies at

$z>2$

with

$M_*>10^{10}\, \mathrm{M}_\odot$

from PRIMER and JADES photometry spanning a total area of

$\simeq 320$

sq. arcmin. Our analysis is restricted to only area with optical coverage in three Hubble Space Telescope (HST) ACS filters, which we show is important for selecting the most complete and clean samples. We investigate the contamination in our sample via James Webb Space Telescope (JWST) NIRSpec spectroscopy,

$Chandra$

X-ray imaging, and ALMA interferometry, calculating a modest contamination fraction of

$12.9_{-3.1}^{+4.0}$

per cent. The removal of HST data increases star-forming galaxy contamination by

$\simeq 10$

per cent and results in a

$\simeq 20$

per cent loss of candidates recovered from HST + JWST data combined. We calculate massive quiescent galaxy number densities at

$2< z< 5$

, finding values three times larger than pre-JWST estimates, but generally in agreement with more-recent and larger-area JWST studies. In comparison with simulations, we find that most can now reproduce the observed number density at

$2< z < 3$

; however, they still increasingly fall short at

$z>3$

, up to

$\simeq 1$

dex. We place 14 of our

$z>3$

massive quiescent galaxies on the BPT and WHaN diagrams using medium-resolution spectroscopic data from the EXCELS survey, finding a very high incidence of weak active galactic nucleus (

$\simeq 50$

per cent), consistent with recent results at cosmic noon. This is interesting in the context of 'maintenance-mode' feedback, which is invoked in many simulations to prevent the re-ignition of quenched galaxies. To properly characterize the evolution of early massive quiescent galaxies, greater coverage in optical filters and significantly larger spectroscopic samples will be required.

A near-infrared stellar atlas of the Galactic plane from the VVVX survey

First Author: Alonso-Garcia, Javier
Instruments: VIRCAM
ProgramIDs: 198.B-2004
BibCode: 2026A&A...706A.301A

Context. The VISTA Variables in the Via Lactea eXtended (VVVX) ESO public survey observed the Galactic plane and the outer Galactic bulge in the near-infrared to mitigate the effects of extinction that severely limit optical observations of these regions. By significantly expanding the area covered by the original VVV survey, VVVX enables a deeper and broader exploration of the most obscured and crowded regions of the Milky Way. Aims. We aim to extend and complete our photometric catalogs of the entire Galactic plane region accessible from the southern hemisphere, focusing on the areas newly covered by the VVVX survey. Methods. Building on previous work, we applied point-spread function fitting techniques to detect point sources and extract their deep J, H, and K_s photometry across the VVVX footprint. The resulting catalogs were calibrated using astrometric and photometric reference data. Cross-matching between filters and epochs was used to ensure a high level of reliability and completeness. Results. We produce a deep, highly complete near-infrared catalog of more than 700 million sources in the Galactic plane and outer Galactic bulge. When combined with our previous VVV atlas, the full catalog includes over 1.5 billion sources. The derived density maps and color─magnitude diagrams enable detailed studies of Galactic structure, extinction, and stellar populations, and highlight features such as the Carina arm tangency, the Sagittarius stream, and numerous star clusters. Conclusions. This extended atlas provides an unprecedented view of the innermost regions of the Milky Way. It is now publicly available through the VISTA Science Archive, offering a valuable resource for the astronomical community to investigate the structure and evolution of the Galactic disk and bulge.

MINDS: Complementary inclinations in the binary system HK Tau reveal gas- and ice-phase chemistry

First Author: Somigliana, Alice
Instruments: ALMA_Band_6, ALMA_Band_7
ProgramIDs: 2016.1.00460.S, 2018.1.00771.S
BibCode: 2026A&A...711A.276S

HK Tau is a roughly equal-mass pre-main-sequence binary system consisting of a low-inclination primary (57°) and an edge-on (83°) secondary. We present JWST Mid-Infrared Instrument (MIRI) observations targeting both sources, taken as part of the JWST GTO program MIND. The mid-infrared spectra reveal a line-rich CO₂-dominated primary and a line-poor secondary. This evidence, albeit in line with the evolution-motivated trend uncovered by recent observations of binaries at MIRI wavelengths, is likely due to the different configuration of the two sources. Thermochemical disc models coupled with radiative transfer indeed show that at inclinations comparable to that of HK Tau B, only ionised atomic lines are expected to remain visible in the spectra. While it blocks molecular emission lines, however, the edge-on configuration allows ice absorption bands to be visible against the continuum. In this framework, the HK Tau system provides an unprecedented opportunity for a simultaneous view of the solid and gaseous component of a pair of coeval protoplanetary discs thanks to the complementary inclination of the two sources. We detect water ice at 6.2 and 13.6 μm, CO₂ ice at 15.2 μm, and NH₄⁺ ice at 6.85 μm in the spectrum of HK Tau B. An additional absorption band between 8.3 and 9 μm is compatible with both silicate stretching and C-H bending. Neither the primary nor the secondary shows signs of polycyclic aromatic hydrocarbons. Extended H₂ emission is present around both sources, but is much more elongated in HK Tau B. The distinctive X shape centred at the location of B, combined with the intensity, morphology, and spectral characteristics of the ionised atomic lines [Ar II], [Ne II], and [Ne III], suggests a low-velocity wind origin with a wide (~ 70°) semi-opening angle. The lower forbidden line fluxes and smaller spatial extent of the H₂ emission around A imply that if a wind is launched from the primary as well, it is too cold or dense to be ionised and emit brightly.

An ACA Map of a Molecular Cloud Interacting with Supernova Remnant W28

First Author: Tu, Tian-Yu
Instruments: ALMA_Band_7
ProgramIDs: 2024.1.00194.S
BibCode: 2026ApJ..1006..242T

Supernova remnants (SNRs) strongly influence the physical and chemical properties of the molecular clouds (MCs) with which they interact. We carried out a high-resolution observation toward W28F, a chemically rich MC interacting with SNR W28, with the Atacama Compact Array (ACA) in Band 7. Significant emission (>10σ) of CO, CH₃OH, p-H₂CO, SiO, and SO is detected. We reveal the clumpy structures of the shocked MC, with different spatial distributions between CH₃OH and SiO. We select six molecular clumps to conduct spectral decomposition and non─local thermodynamic equilibrium analysis with the CH₃OH and p-H₂CO lines. The best-fit results show a H₂ density of nH2∼1 ─3 × 10⁵ cm⁻³ and a gas temperature of T_gas ∼ 50─170 K in most of the fitted components. The H₂ density and gas temperature show a clear anticorrelation across different regions, with the thermal pressure consistent with that of the adjacent X-ray-emitting hot plasma. This is consistent with the picture that the SNR shocks propagate into multiphase gas, with a pressure balance existing between different phases. We propose that the high abundance ratio between E-CH₃OH and A-CH₃OH (>0.9) suggests extra gas-phase processes to enhance this ratio, such as proton exchange with H3+ and HCO⁺. The chemical segregation between CH₃OH and SiO, in both the spatial and spectral regime, can be explained by the fact that CH₃OH traces slow shocks while SiO traces fast shocks.

ALMA-QUARKS: Few-thousand-year ''Hatching out of the Egg:'' The Supersonic Breakout of a Hypercompact H II Region from Its Parental Hot Core

First Author: Zhang, Siju
Instruments: ALMA_Band_3, ALMA_Band_6
ProgramIDs: 2019.1.00685.S, 2021.1.00095.S
BibCode: 2026ApJ...997..201Z

The kinematic evolution of hypercompact (HC) H II regions around young high-mass stars remains poorly understood due to complex interactions with parental environs. We present Querying Underlying Mechanisms of Massive Star Formation with Atacama Large Millimeter/submillimeter Array─Resolved Gas Kinematics and Structures (ALMA-QUARKS) 1.3 mm and ATOMS 3 mm observations (the highest resolution is ∼0.01 pc) of a deeply embedded HC H II region (diameter ∼ 0.015 pc, electron density ∼ 2 × 10⁵ cm⁻³) exhibiting a striking ≳20 km s⁻¹ global redshift seen in optically thin H30α and H40α recombination lines relative to its parental hot molecular core within a hub─filament system. The 1.3 mm continuum data reveal a distinct 0.1 pc arc and a perpendicular 0.04 pc tail. We propose that this morphology arises from a dynamic champagne flow: the slow expansion of an HC H II region into a preexisting filament forms an arc and associated low-velocity (few kilometers per second) SiO shocks. Meanwhile, in the opposite direction ionized gas escapes along a steep density gradient traced by a tail and high-velocity (20 km s⁻¹) SiO emission. We reject the bow shock scenario in which ionized gas comoves with a runaway high-mass star because shocked gas in the arc aligns with the hub velocity, contradicting the bow shock prediction. Non-LTE radiative transfer modeling further rules out infall of ionized gas as the velocity shift origin. We conclude that this exceptional HC H II region is undergoing a few-thousand-year transition phase of "hatching out of the egg:" the ionized gas of the HC H II region has just broken out of its parental hot core and now is flowing outward supersonically. This work highlights how anisotropic density distributions induce supersonically anisotropic ionized flows that govern HC H II region evolution.

Characterizing Candidate Blazar Counterparts of the Ultra-high-energy Event KM3-230213A

First Author: Adriani, O.
Instruments: ALMA_Band_3, ALMA_Band_6, ALMA_Band_7
ProgramIDs: 2011.0.00001.CAL
BibCode: 2026AJ....172..139A

High-energy astrophysical neutrinos serve as crucial messengers for understanding hadronic acceleration processes and identifying the origins of cosmic rays, with blazars among the most promising neutrino sources. The KM3NeT experiment reported the detection of an ultrahigh-energy neutrino with an energy estimate of ∼220 PeV, the most energetic yet observed. The neutrino arrival direction has a 99% confidence region of 3° radius centered at R.A. 94 .° 3, decl. −7 .° 8 (J2000). In this work, 17 candidate blazars located within this region are identified. Comprehensive new observations and archival data analysis for these sources are presented. The study provides a complete multiwavelength coverage across radio, optical, X-ray, and gamma-ray bands, including proprietary data and dedicated follow-up observations. This study highlights flaring behavior in several candidate counterparts. One object exhibits a radio flare coinciding with the neutrino arrival time, with a pre-trial chance probability of 0.26%. Only for this object, the chance probability could be quantified in a robust way. Another candidate displays a rising trend in X-ray flux in a 1 yr window around the neutrino arrival time, while a third undergoes a gamma-ray flare during the same period. Based on the observational findings presented here, while none of these candidates can conclusively be linked to the neutrino, the implications of a possible blazar origin for the KM3NeT event are discussed.

A search for circumstellar gas in pre-main-sequence debris discs using absorption spectroscopy

First Author: Szewczyk, Karolina M.
Instruments: ALMA_Band_6, FEROS, FLAMES, GIRAFFE, HARPS, UVES
ProgramIDs: 099.C-0491, 078.A-9059, 0101.D-0697, 098.C-0739, 68.C-0548, 072.C-0488, 087.A-9013, 080.C-0712, 076.C-0279, 182.D-0356, 090.C-0421, 085.D-0093, 079.B-0856, 099.A-9022, 0106.A-9006, 089.D-0129, 089.C-0006, 079.A-9009, 075.D-0676, 099.D-0380, 087.C-0012, 194.C-0833, 092.C-0721, 073.D-0049, 085.A-9027, 098.C-0463, 0102.A-9008, 0103.C-0206, 096.A-9024, 0103.A-9009, 084.A-9011, 075.C-0479, 083.A-9013, 090.D-0358, 088.A-9029, 097.C-0090, 088.D-0026, 073.D-0641, 0103.A-9011, 0102.A-9010, 082.C-0831, 073.D-0724, 0100.A-9006, 077.D-0247, 0102.C-0584, 087.B-0600, 085.C-0019, 093.C-0409, 0101.A-9001, 0101.D-0415, 077.C-0575, 096.A-9027, 293.D-5036, 0101.D-0921, 089.D-0975, 083.C-0139, 098.A-9039, 380.C-0083, 077.C-0295, 093.D-0302, 096.A-9018, 074.D-0021, 073.A-9008, 076.D-0018, 099.A-9009, 096.A-9039, 0102.D-0281, 097.A-9024, 097.A-9022, 0101.A-9016, 083.C-0676, 080.D-0194, 082.C-0446, 183.C-0972, 075.C-0637, 185.D-0056, 072.D-0021, 0106.A-9009, 074.C-0135, 099.C-0637, 095.A-9029, 078.D-0080, 092.A-9006, 076.D-0169, 0100.C-0090, 178.D-0361, 67.D-0133, 077.D-0720, 165.N-0276, 082.B-0484, 0104.A-9001, 084.B-0029, 079.D-0567, 075.D-0145, 074.D-0240, 080.C-0032, 079.C-0170, 074.C-0102, 075.C-0234, 082.C-0308, 076.C-0073, 099.A-9029, 179.C-0197, 075.D-0760, 190.C-0027, 083.A-9014, 266.D-5655, 075.D-0324, 081.C-0475, 079.A-9014, 079.D-0118, 077.C-0547, 073.C-0337, 075.D-0103, 087.C-0831, 0101.C-0232, 088.C-0353, 0103.C-0548, 097.C-0409, 091.C-0713, 67.D-0579, 079.C-0789, 0104.A-9010, 084.D-0067, 0100.C-0097, 0102.C-0338, 074.D-0008, 0104.A-9004, 184.C-0815, 094.C-0946, 081.C-2003, 66.D-0457, 093.C-0658, 0102.C-0547, 0104.A-9003, 083.D-0034, 60.A-9700, 077.C-0192, 075.C-0689, 097.D-0150, 095.A-9032, 0100.C-0414, 71.B-0529, 0108.A-9006, 087.A-9029, 087.D-0950, 079.D-0009, 0104.C-0418, 091.D-0221, 092.A-9002, 0101.A-9005, 072.D-0149, 087.D-0010, 0108.A-9029, 092.C-0173, 075.D-0597, 0102.C-0040, 096.C-0238, 094.A-9012, 082.D-0061, 69.C-0171, 095.D-0717, 080.D-0191, 072.D-0196, 077.D-0478, 0103.D-0119, 109.23K8, 110.23YZ, 112.262P, 113.26V6, 106.20Y7, 105.20L8, 105.2045, 106.21R4, 105.2055, 2022.1.01686.S
BibCode: 2026MNRAS.550g1309S

Gas in debris discs is thought to be either inherited from the protoplanetary stage or released from the solid, rocky content of planetesimal belts. Its presence can impact planetary atmospheres and their potential for habitability, which stresses the need to ascertain its origin and composition. Most detections to date are around main-sequence stars, with only a few gas-bearing debris discs identified around pre-main-sequence stars, mainly through millimetre CO line searches. We investigate narrow gas absorption features superimposed on the photospheric Ca II K & H and Na I D1 & D2 lines in a sample of 125 pre-main sequence and 5 relatively young (< 17 Myr) stars. All stars are associated with IR excess emission indicative of the presence of a debris disc. By comparing their residual spectra (photosphere-subtracted) to those of nearby stars, interstellar cloud velocities, and stellar radial velocities, we test whether interstellar absorption is the culprit and ascertain the circumstellar gas origin. Using these methods, out of the 130 targets, we identified two new gas-bearing debris discs: TYC 7879-1373-1, which exhibits stable absorption, and HIP 30414, which shows variable gas absorption features linked likely to ongoing accretion. Both these systems are pre-main-sequence stars younger than 5 Myr. TYC 6822-283-1 has absorption features of inconclusive origin. This study increases the number of currently known very young (< 10 Myr) debris discs with circumstellar gas to eight, paving the path to future systematic studies of objects caught in transition from protoplanetary to debris disc stages.

A Streamer Driving Misalignment in the Circumtriple Disk of GW Ori

First Author: Galloway-Sprietsma, Maria
Instruments: ALMA_Band_6
ProgramIDs: 2022.1.01108.S, 2017.1.00286.S
BibCode: 2026AJ....172..138G

GW Ori is a triple stellar system with a disk featuring three misaligned dust rings. We present Atacama Large Millimeter/submillimeter Array molecular line data of CO isotopologues, revealing a streamer feeding the disk in ¹²CO and ¹³CO. Through multipointing observations, we find the streamer extends to ∼30″ on-sky (∼12,000 au) and estimate a mass of 1.6 M_Jup using ¹³CO. Fitting the morphology and kinematics of the streamer, we estimate a mass infall timescale of 0.04 Myr and a mass infall rate of 3.6 × 10⁻⁸ M_⊙ yr⁻¹, approximately an order of magnitude lower than the stellar accretion rate. Our best-fit trajectory shows that the streamer meets the disk at the outermost dust ring and that the streamer's angular momentum vector is closely aligned with this outermost ring within ≍3^∘, in contrast to the ≍32^∘misalignment with the innermost ring, suggesting the streamer is the likely cause of the misalignment. However, the total angular momentum of the streamer is smaller than that of GW Ori's disk; this, together with the low accretion rate, indicates that we are probably witnessing the end stages of infall. Total Power observations reveal bright emission connecting the streamer to the surrounding star-forming region, with the projected distance falling well within the Bondi─Hoyle radius, implying the streamer could have originated through Bondi─Hoyle accretion as GW Ori moves through its natal cloud. Together, these results suggest that GW Ori remains dynamically linked to its parental cloud through ongoing accretion, with the streamer serving as the likely driver of its misaligned disk structure.

The multiphase biconical outflow in the local infrared-luminous merger IRAS F01364-1042

First Author: Song, Y.
Instruments: ALMA_Band_3, ALMA_Band_6, ALMA_Band_7
ProgramIDs: 2017.1.01235.S, 2018.1.00279.S, 2019.1.00811.S
BibCode: 2026A&A...712A..59S

Aims. We investigate the spatially resolved (interstellar medium) ISM properties of the local (z = 0.048), infrared-luminous (L_IR = 10^11.87 L_⊙), late-stage galaxy merger IRAS F01364-1042. We combined multiwavelength IFU observations from JWST/MIRI-MRS, ALMA, and Keck/KCWI. The system exhibits excess emission from mid-infrared (MIR) H₂ lines relative to dust, as identified in a previous Spitzer/IRS survey of local IR-luminous galaxies (LIRGs). It has been speculated that the bright H₂ emission could arise from widespread shocks associated with a powerful outflow driven by starburst and/or active galactic nucleus (AGN) activity. Methods. Using our multiwavelength datasets, we assessed and compared the resolved morphology and kinematics of multiphase gas tracers on subkiloparsec (subkpc) scales. We constructed emission line maps of several key tracers of the ionized, warm molecular, and cold molecular gas, such as [Ne II] 12.8μm, [O III]λ5007, H₂ 0-0 S(3), and CO (J = 2-1), respectively. We performed a detailed decomposition of spectra extracted in resolved regions across the areas of emission, with a focus on the central ∼3 kpc of the system covered by all our datasets. Results. We confirm the presence of a multiphase galactic biconical outflow along the minor axis of a highly inclined rotating disk, based on the multiphase gas morphology and prominent line broadening (FWHM > 500 km s⁻¹) in the ionized gas tracers detected out to ∼5 kpc from the nucleus. The molecular gas tracers are detected out to ∼2 kpc, exhibiting a distinct X-shaped morphology and different velocity fields compared to the ionized gas, which we attribute to the higher concentration of molecular gas near the disk. We adopted a simple model to interpret the observed multiphase gas kinematics and infer an outflow velocity of ∼500─600 km s⁻¹ ∼350 km s⁻¹, and ∼200─300 km s⁻¹, in the ionized, warm, and cold molecular phases, respectively. The corresponding mass outflow rates are ∼0.3 − 2.3, ∼31, and ∼38 − 240 M_⊙ yr⁻¹. The cold molecular phase dominates both the total mass outflow rate and the associated kinetic energy (∼2 − 8 × 10⁴² erg s⁻¹). Via the JWST/MIRI-MRS detection of the [Ne V] 14.3μm line, we identified, for the first time, a dust-obscured AGN in IRAS F01364-1042. The low inferred AGN bolometric luminosity (1.2 − 1.8 × 10⁴³ erg s⁻¹) suggests that the nuclear starburst alone, with a star formation rate of ∼40 − 60 M_⊙ yr⁻¹, can account for the energy required to drive the outflow, although a more active AGN phase in the recent past might also have played a role. Conclusions. Our work showcases the need for multiwavelength observations in interpreting the gas dynamics in merger-driven dusty starbursts, as well as the capability of JWST/MIRI-MRS in uncovering obscured low-luminosity AGNs that could prove common in these systems.

Resolving stellar populations, star formation, and interstellar medium conditions with JWST in a large spiral galaxy at z ≍ 2

First Author: Parlanti, Eleonora
Instruments: ALMA_Band_6
ProgramIDs: 2018.1.01044.S
BibCode: 2026A&A...712A..92P

Cosmic noon represents the prime epoch where today's massive galaxies assembled most of their stellar masses, and it is an ideal period for observations with both the space-based James Webb Telescope (JWST) and ground-based near-IR integral-field unit (IFU) spectrographs. This work analyzes JWST NIRSpec Micro Shutter Array (MSA) and NIRCam Wide Field Slitless Spectroscopy (WFSS) observations of K20-ID7, a large spiral, star-forming (SF) galaxy at z = 2.224 with evidence of radial gas inflows. Leveraging ground-based IFU ERIS observations, we conducted a comprehensive and resolved study of the interstellar medium and stellar properties of this galaxy, covering the rest-frame optical to near-IR. Our analysis ─ using several emission-line diagnostics, resolved spectral energy distribution (SED) fitting of high-resolution imaging, and Paβ line detection in NIRCam WFSS data ─ reveals massive SF clumps (M_★ ≃ (0.67 − 3.5) × 10⁹ M_⊙) with star formation rates (SFRs) of 3 − 24 M_⊙ yr⁻¹, low dust attenuation (A_V ≃ 0.4), electron densities (n_e ≲ 300 cm⁻³), and ionization parameter (log(U) ≃ −3.0). The central bulge is modestly massive (M_★ = (7 ± 3)×10⁹ M_⊙), heavily obscured (A_V = 6.43 ± 0.55), and likely formed most of its stellar mass in the past (SFR = 82 ± 42 M_⊙ yr⁻¹ over the last ∼100 Myr). Yet, it continues to form stars at a lower rate (SFR = 12 ± 8 M_⊙ yr⁻¹ over the last ∼10 Myr). We infer a relatively low sulfur abundance of log(S/O) ≃ −1.9, which may have implications for sulfur production via type I supernova explosions. Moreover, all distinct galaxy regions feature a metallicity of 12+log(O/H) ≍ 8.54, likely due ─ along with the enhanced N/O abundance (i.e., log(N/O) ≃ −1.0) ─ to dilution effects from radial inflows of metal-poor gas. Lastly, we find tentative evidence of a negative gradient in stellar age, suggesting possible inside-out growth for K20-ID7.

Magnetic field strengths of hot giant exoplanets consistent with Solar System values

First Author: Seidel, Julia V.
Instruments: ESPRESSO
ProgramIDs: 107.22QF, 111.24J8, 109.22Z4, 1104.C-0350, 0104.C-0605, 60.A-9128, 106.21R1, 0104.C-0642, 1102.C-0744, 106.20ZN, 0102.C-0311
BibCode: 2026NatAs..10.1145S

Magnetic fields are a key factor in the evolution of planets and their atmospheres, but they are still poorly constrained for exoplanets owing to limited direct observations. Ultra-hot Jupiters provide a new avenue to probe magnetic effects, as the circulation of their highly ionized atmospheres could be directly sensitive to the atmospheric magnetic field. However, it remains unclear whether the impact of these magnetic effects can be observed directly and used to constrain the magnetic field strength. With high spectral resolution observations targeting the planetary iron lines, we measure the Doppler shift and thus the wind speed of seven transiting ultra-hot Jupiters. Here we find a clear decrease of wind speed with increasing planetary temperature, which is a trend inconsistent with purely hydrodynamic mechanisms but naturally reproduced by magnetic drag. From this relationship, we estimate the possible strength of magnetic fields of hot giant planets to at most a few gauss, which is comparable with the Jovian equatorial field. Our results support the idea that magnetic fields affect the atmospheric circulation of ultra-hot Jupiters and could provide a crucial benchmark for scaling laws used to predict magnetic fields in exoplanets, from hot Jupiters to rocky Earths, with additional implications for future direct observations.

Active Galactic Nuclei─driven Metallicity Enrichment in the Interstellar Medium of Mrk 573

First Author: Król, D. Ł.
Instruments: MUSE
ProgramIDs: 106.21C7
BibCode: 2026ApJ..1000L..43K

We present the first spatially resolved at ∼20 pc scale application of active galactic nuclei (AGN)-specific metallicity diagnostics for the nearby Compton-thick Seyfert 2 galaxy Mrk 573 (z = 0.017). We use Hubble Space Telescope narrowband imaging, MUSE integral-field spectroscopy, and apply AGN strong-line metallicity diagnostics based on [O III], [S II], Hβ, Hα, and [N II] emission lines. We construct maps of 12+log(O/H) for two different metallicity calibrations and two different N/O─O/H scaling relations out to ∼1 kpc and down to ∼20 pc scales. Our analysis reveals metallicity enhancement in AGN-dominated regions, with oxygen abundances reaching up to a few times solar. The metallicity shows a patchy spatial distribution, varying on ∼100 pc scales, which appears to trace the high Seyfert/ low-ionization nuclear emission-line region index value regions and the Very Large Array 6 cm jet/radio lobe emission. These spatial correspondences and the lack of evidence for star formation in the bicone region suggest that the enrichment originates from metals transported from the nuclear AGN regions by winds, outflows, or jets.

Time-variable Scattered Light in Herbig Disks Observed with Subaru/SCExAO

First Author: Mullin, Camryn
Instruments: SPHERE
ProgramIDs: 0102.C-0916, 0104.C-0122, 198.C-0209, 096.C-0248, 098.C-0760, 0100.C-0408, 0100.C-0452, 0101.C-0867, 108.22EE, 0102.C-0453, 106.21HJ, 0104.C-0157, 1104.C-0415, 0103.C-0470, 60.A-9389, 60.A-9800, 095.C-0273, 096.C-0523, 097.C-0523, 097.C-0702, 097.C-0902, 297.C-5023, 111.24GG, 109.23BC, 105.20HV, 105.20JB, 105.209E, 0104.C-0850, 0104.C-0472, 0102.C-0778, 0102.C-0162, 0101.C-0464, 0100.C-0647, 099.C-0147, 098.C-0486
BibCode: 2026AJ....171..241M

Using the Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) instrument, we present near-infrared K-band polarimetric imaging of nine Herbig stars selected from a volume-limited sample within 200 pc. We detect the disks around MWC 480, HD 163296, and HD 143006 for the first time with SCExAO, and compare these observations with previous Very Large Telescope/SPHERE datasets to identify surface-brightness variability. In MWC 480, we resolve two azimuthal brightness dips near the disk minor axis and find evidence that one of them shifted between 2021 and 2022. In HD 163296, we identify an apparent linear azimuthal motion of a localized peak in polarized intensity along the outer ring over a 15 month baseline. The rapid motion of these features relative to the local Keplerian velocity suggests that the observed variability is driven by changing illumination rather than physical material motion. Due to uncertainties in the underlying scattering background, however, we cannot determine the precise physical origin of the variability. No significant disk variability is detected in HD 143006 over a 10 month baseline. We also report the first detection of a protoplanetary disk using the fast polarimetric differential imaging mode on SCExAO, illustrating both the promise and current limitations of this observing mode. Finally, we report nondetections toward HD 144432, HD 56895, PDS 76, HIP 80425, HD 148352, and HIP 81474. All nondetections with Meeus classifications belong to Group II systems and are likely self-shadowed. For these six systems, we measure the system-integrated polarization fraction and angle of linear polarization, providing quantitative constraints on their unresolved circumstellar environments. *This research is based in part on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.

Modelling the photometric and morphological evolution of disc galaxies in the cluster environment

First Author: Marasco, A.
Instruments: OMEGACAM
ProgramIDs: 093.A-0041, 091.A-0059, 090.A-0074, 089.A-0023, 088.A-4005
BibCode: 2026A&A...708A..18M

Compelling observational evidence indicates that the disc population in galaxy clusters has undergone rapid evolution, transitioning from a dominance of blue spirals to red lenticular galaxies (S0s) over the past ∼7 Gyr. We built a simplified cluster evolutionary model in the standard cosmological framework to constrain the characteristic timescales of this transformation. In our model, all field spirals joining the cluster at various redshifts are subject to ram-pressure stripping (RPS), which removes their gas reservoir leading to the quenching of their star formation on a timescale, t_s, and to an (initially) unspecified mechanism that transforms them into S0s on a timescale, t_m. We assume that t_s and t_m are independent and both power-law functions of the galaxy-to-cluster mass ratio, M_★/M_cl. We constrained our model using the observed distribution of spirals and S0s in a colour-mass plane from the OmegaWINGS and EDisCS cluster surveys at z ≃ 0.055 and z ≃ 0.7, respectively. Our best-fit model reproduces the data remarkably well, especially at low redshift, and predicts evolutionary trends for the main morphological fractions in agreement with previous studies. We find typical t_s values between 0.1 and 1 Gyr, compatible with previous estimates, supporting RPS as the most efficient quenching mechanisms in clusters. A surprisingly strong anti-correlation between t_s and M_★/M_cl is required in order to suppress the formation of red, low-mass spirals at low redshift, which we interpret as being driven by orbit anisotropy. Conversely, t_m depends very weakly on M_★/M_cl and has typical values of a few Gyr. The inferred morphological evolution is compatible with that resulting from the ageing of the stellar populations in galaxies that have been abruptly quenched by ram pressure stripping: we confirm spectrophotometric ageing as a key channel for the spiral-to-S0 transition in galaxy clusters, with secular evolution playing a secondary role.

The GLEAM 4-Jy (G4Jy) Sample ─ III. Further host-galaxy identification, and redshift assessment

First Author: White, Sarah V.
Instruments: VIRCAM
ProgramIDs: 179.A-2010
BibCode: 2026MNRAS.547ag187W

In this paper we present 127 new host-galaxy identifications for G4Jy sources (

$S_{\mathrm{151\, MHz}} > 4$

Jy), based on radio images from MeerKAT, the Very Large Array Sky Survey (VLASS), and the Rapid ASKAP (Australian Square Kilometre Array Pathfinder) Continuum Survey (RACS). This includes identifications that result from visual inspection of radio contours on

$K_{\mathrm{S}}$

-band images, as opposed to the AllWISE-W1 images that were used for the original set of overlays when defining the G4Jy Sample (Papers I and II). Our aim is to achieve 100 per cent spectroscopic completeness for the sample, where all of the spectroscopy is available in digital form online. For now, we have gathered (i) digital optical spectroscopy for 34 per cent of the sample, (ii) photometric redshifts for an additional 21 per cent of the sample, and (iii) further redshifts found through the NASA/IPAC Extragalactic Database (but not recently verified). Our assessment of the redshifts includes visual inspection of all of the digital spectroscopy, and re-fitting redshift templates where necessary. The resulting redshift range is (currently)

$0.0 < z < 3.6$

. We also present 151-MHz luminosities and linear sizes for the G4Jy Sample, based on initial analysis.

Widespread Extended [C II] Emission in High-redshift Galaxies: Insights from the FIRE-2 Cosmological Zoom-in Simulations

First Author: Liu, Lun-Jun
Instruments: ALMA_Band_7
ProgramIDs: 2021.1.00280.L, 2017.1.00428.L
BibCode: 2026ApJ..1007..123L

Recent Atacama Large Millimeter/submillimeter Array observations reveal diffuse [C II] emission ("[C II] halos") extending to ∼10 kpc in galaxies at 4 < z < 6. These measurements provide new insights into high-redshift galactic ecosystems and processes that drive metal enrichment on inner circumgalactic scales. To better understand the nature of [C II] halos, we analyze a suite of high-redshift FIRE-2 simulations at 5 ≤ z ≤ 6 in the stellar mass range of 10⁹─10^10.5 M_⊙. By postprocessing these simulations with three-dimensional dust radiative transfer and photoionization modeling, we generate synthetic images of [C II] and UV continuum emission, from which we extract one-dimensional surface brightness profiles. Our results reproduce both the galaxy-integrated and spatial distribution of [C II] and UV emission, capturing in particular the more extended profile of [C II] emission. Comparing the time evolution of [C II] halos with bursty star formation histories of the simulated galaxies, we find that [C II] emission becomes more spatially extended following the decline of star formation rate in recent starburst episodes. This implies a strong correlation between extended [C II] emission and bursty star formation, consistent with a key role for star formation-driven outflows in producing [C II] halos—though the kinematics of [C II]-emitting gas suggest that inflows and turbulent motions are also significant contributors. We also find a modest contribution from satellite galaxies to extended [C II] emission. Our framework can be readily applied to predict the observability of [C II] halos at higher redshifts and extended to create spatially resolved synthetic observations of other important emission lines, such as [O III] and Hα.

Direct Tests of Black Hole Accretion Rate Prescriptions. I. Bondi Accretion at Different Scales

First Author: Agostino, James
Instruments: ALMA_Band_6
ProgramIDs: 2017.1.01666.S
BibCode: 2026ApJ..1007...23A

We present spatially resolved parsec-scale measurements of nuclear conditions (gas density and kinetic temperature) relevant for black hole accretion rate predictions in the Seyfert 2 galaxy, NGC 1068. We inject these parameters into the prescription for a Bondi-like accretion model, then compare the resulting accretion rate prediction to the empirical accretion rate derived from hard X-ray observations. Cosmological simulations have spatial resolution ranging from ∼10 pc to approximately kiloparsec scales, and so for reasonable comparison we test these accretion rate predictions in pixel-sized radial steps out to 500 pc. Compared to warm H₂ gas, CO gas is the dominant mass carrier close to the SMBH. We find that the Bondi accretion rate ( ṀBondi ) of cold molecular gas alone (measured using CO) overestimates the true accretion rate by up to 14 dex in a small aperture (r ≲5 pc) around the black hole, and by at least 8 dex inside large apertures (r ≲500 pc). These results are the first in a series of direct tests of accretion rate prescriptions, and they suggest that using a Bondi accretion formalism to model supermassive black hole accretion in Seyfert 2 galaxies may lead to overestimated accretion rates in simulations.

Gravitationally Lensed View of DSFG-1 in PLCK G165.7+67.0: Strong Dust Emission and Spatially Resolved Stellar Population Analysis with JWST and SMA

First Author: Yan, Zhiyu
Instruments: ALMA_Band_3, ALMA_Band_4
ProgramIDs: 2021.1.00607.S
BibCode: 2026ApJ..1007...44Y

We present a detailed stellar population analysis of the strongly lensed dusty star-forming galaxy (DSFG) PLCK G165.7+67.0 DSFG-1 at z = 2.236, combining JWST NIRCam imaging with new Submillimeter Array (SMA) observations. This source is multiply imaged into two lensed components: image 1a, with a moderate magnification factor of μ ∼ 5, and image 1bc, with an extreme magnification factor of μ ∼ 40. The new SMA observations detect significant dust continuum emission at 225 and 273 GHz, with combined flux densities of S_cont = 1.19 ± 0.38 mJy in image 1a and S_cont = 10.02 ± 0.85 mJy in image 1bc, indicating active star formation at subkiloparsec scales. Based on the integrated spectral energy distribution modeling, DSFG-1 exhibits a lensing-amplification-corrected stellar mass of M_⋆ = (1.2 ± 0.4) × 10¹⁰ M_⊙ and a star formation rate of 103 ± 14 M_⊙ yr⁻¹, similar to previous Hα-based results, placing it four times above the star-forming main sequence at this redshift. Its location on the size─mass plane and its morphological properties suggest that the system occupies a transitional phase between star-forming late-type galaxies and compact early-type systems. Together with its elevated star formation activity, this is consistent with a rapidly evolving galaxy observed during cosmic noon. We further investigated the spatially resolved stellar population properties and found significant spatial variations in stellar age and dust attenuation. These results point to a nonuniform star formation history and highlight the complex interplay between dust geometry, stellar growth, and gravitational lensing, consistent with a merger scenario.

A Deep ALMA Survey of the Redshift Distribution of Dusty Star-forming Galaxies

First Author: McKay, S. J.
Instruments: ALMA_Band_3, ALMA_Band_4, ALMA_Band_6, ALMA_Band_7
ProgramIDs: 2021.1.00024.S, 2024.1.01213.S, 2015.1.00242.S
BibCode: 2026ApJ..1007...61M

We present an Atacama Large Millimeter/submillimeter Array spectroscopic follow-up survey of an 870 μm selected sample of dusty star-forming galaxies (DSFGs) in the GOODS-S field. We use these line scans to identify or confirm spectroscopic redshifts (spec-zs) for 26 sources. Including spec-zs from the literature, there are now secure or tentative spec-zs for 54 out of 75 DSFGs (72%). At f_{870 μm} > 2.5 mJy, the sample is 97% spectroscopically complete, allowing us to model the full DSFG redshift distribution down to nearly the confusion limit for a 15 m telescope at 850 μm. This is the highest completeness for an unbiased sample at this flux limit to date. We find that nearly all of the DSFGs in our sample that were targeted with JWST/NIRSpec were spectroscopically identified, without much dependence on near-infrared or submillimeter flux or redshift. However, only 29% of our sample have JWST spectroscopic coverage. We use the spec-zs to evaluate various photometric redshift (photo-z) estimates, finding that all methods exhibit an outlier fraction of at least >20%. Nearly all of the photo-z methods tend to overshoot the redshifts, leading to overestimates of the number of DSFGs at high redshift (z > 4). Our results suggest that ≲6% of f_{870 μm} ≥ 2.25 mJy DSFGs lie at z > 4 and ≲1% lie at z > 5, reflecting a steep decline in the abundance of massive dusty galaxies in the first 1.5 Gyr.

Ultra-diffuse galaxies in the Kilo-Degree Survey with deep learning

First Author: Su, Hao
Instruments: OMEGACAM, VIRCAM
ProgramIDs: 179.A-2004, 177.A-3018, 177.A-3017, 177.A-3016
BibCode: 2026A&A...707A.354S

Ultra-diffuse galaxies (UDGs) are a subset of low-surface-brightness galaxies (LSBGs), showing mean effective surface brightness fainter than 24 mag arcsec⁻² and a diffuse morphology, with effective radii larger than 1.5 kpc. Due to their elusiveness, using traditional methods over large sky areas is challenging. Here we present a catalog of UDG candidates identified in the full 1350 deg² area of the Kilo-Degree Survey (KiDS) using deep learning. In particular, we used a previously developed network for the detection of low-surface-brightness systems in the Sloan Digital Sky Survey (SBGnet) and optimized for UDG detection. We trained this new UDG detection network for KiDS (UDGnet-K), with an iterative approach, starting from a small-scale training sample. After training and validation, the UGDnet-K has been able to identify ∼3300 UDG candidates, of which, after visual inspection, we selected 545 high-quality ones. The catalog contains the independent rediscovery of previously confirmed UDGs in local groups and clusters (e.g., NGC 5846 and Fornax), and new discovered candidates in about 15 local systems, for a total of 67 bona fide associations. Besides the value of the catalog per se for future studies of UDG properties, this work shows the effectiveness of an iterative approach to training deep learning tools in presence of poor training samples, due to the paucity of confirmed UDG examples, which we expect to replicate for upcoming all-sky surveys such as those by the Rubin Observatory, Euclid, and the China Space Station Telescope.

Identifying evolutionary stages of molecular clumps through unsupervised and supervised machine learning

First Author: Plakitina, K. V.
Instruments: LABOCA
ProgramIDs: 085.F-9526, 085.F-9505, 082.F-9701, 080.F-9701, 081.C-9501, 079.C-9501, 078.F-9040, 181.C-0885
BibCode: 2026MNRAS.547ag373P

The evolutionary classification of molecular clumps, crucial for understanding star formation, is commonly based on human-assigned categories derived from infrared (IR) emission and well-established morphological criteria. However, due to ambiguous signatures, distance uncertainties or heavily obscured IR emission, a significant fraction of sources often remains unclassified. This work demonstrates the capability of machine learning (ML) as a complementary, data-driven approach to automate the identification and classification of these clumps using data from the MALT90 survey, complemented by Spitzer IR photometry. We applied unsupervised clustering with HDBSCAN on molecular line intensities, revealing distinct groupings that correspond to evolutionary stages. Using only five molecular lines (HCO

$^+$

, HNC, N

$_2$

$^+$

, HCN, C

$_2$

H), we identified stable clusters of protostars and regions without active star formation, driven primarily by C

$_2$

H and N

$_2$

$^+$

emission. Incorporating H

$^{13}$

$^+$

gave rise to a distinct UV-dominant cluster, tracing more evolved regions. Infrared properties appeared as non-significant features implying that envelopes of clumps with different masses are similar in their global infrared characteristics. We then employed supervised learning to classify clumps with previously uncertain categories and provided classifications for 522 objects, predominantly as regions without active star formation. Our results show that ML techniques can effectively uncover intrinsic evolutionary structures in complex astrochemical data and assign categories to uncertain sources, providing a powerful, data-driven complement to traditional methods.

Counting Little Red Dots at z < 4 with Ground-based Surveys and Spectroscopic Follow-up

First Author: Ma, Yilun
Instruments: VIRCAM
ProgramIDs: 179.A-2005, 179.A-2006
BibCode: 2026ApJ..1000...59M

Little red dots (LRDs) are a population of red, compact objects discovered by JWST at z > 4. At 4 < z < 8, they are roughly 100 times more abundant than UV-selected quasars. However, their number density is uncertain at z < 4 due to the small sky coverage and limited blue wavelength coverage of JWST. We present our ground-based search for LRDs at 2 ≲ z ≲ 4, combining ultradeep Hyper Suprime-Cam photometry and various (near-)infrared surveys within a total area of ∼3.1 deg². We find that for LRDs with M₅₅₀₀ < −22.5, their number density declines from ∼10^−4.5 cMpc⁻³ at z > 4 to ∼10^−5.3 cMpc⁻³ at 2.7 < z < 3.7 and ∼10^−5.7 cMpc⁻³ at 1.7 < z < 2.7. We also present the Magellan/FIRE spectrum of our first followed-up candidate, DEEP23-z2LRD1 at z_spec = 2.26, as a proof of concept for our sample selection. Similar to high-redshift LRDs, the spectrum of DEEP23-z2LRD1 exhibits broad Hα emission with FWHM ≍ 2400 km s⁻¹ and with nearly symmetric narrow Hα absorption. Additionally, DEEP23-z2LRD1 has extremely narrow [O III] lines with FWHM ≍ 140 km s⁻¹, suggesting the presence of an accreting black hole in a low-mass host galaxy. Limited by the angular resolution of ground-based surveys, we emphasize that spectroscopic follow-ups are required to characterize the contamination fraction of this sample and pin down LRD number density at z < 4.

Downsizing does not extend to dwarf galaxies: identifying the stellar mass regimes shaped by supernova and AGN feedback

First Author: Lazar, I.
Instruments: VIRCAM
ProgramIDs: 179.A-2005
BibCode: 2026MNRAS.547ag207L

We explore how the fraction of red (quenched) galaxies varies in the dwarf galaxy regime (10

$^{7}$

$_{\odot }$

$M_{\star }$

< 10

$^{9.5}$

$_{\odot }$

), using a mass-complete sample of

$\sim$

5900 dwarfs at

$z\lt 0.15$

, constructed using deep multi-wavelength data in the COSMOS field. The red fraction decreases steadily until

$M_{\star }$

$\sim$

$^{8.5}$

$_{\odot }$

and then increases again towards lower stellar masses. This 'U' shape demonstrates that the traditional notion of 'downsizing' (i.e. that progressively lower-mass galaxies maintain star formation until later epochs) is incorrect-downsizing does not continue uninterrupted into the dwarf regime. The U shape persists regardless of environment, indicating that it is driven by internal processes rather than external environment-driven mechanisms. Our results suggest that, at

$M_{\star }$

$\lesssim$

$^8$

$_{\odot }$

, the quenching of star formation is dominated by supernova (SN) feedback and becomes more effective with decreasing stellar mass, as the potential well becomes shallower. At

$M_{\star }$

$\gtrsim$

$^9$

$_{\odot }$

, the quenching is driven by a mix of SN feedback and active galactic nucleus (AGN) feedback (which becomes more effective with increasing stellar mass, as central black holes become more massive). The processes that quench star formation are least effective in the range 10

$^{8}$

$_{\odot }$

$M_{\star }$

< 10

$^{9}$

$_{\odot }$

, likely because the potential well is deep enough to weaken the impact of SN feedback, while the effect of AGN feedback is still insignificant. The cosmological simulations tested here do not match the details of how the red fraction varies as a function of stellar mass. We propose that the red fraction versus stellar mass relation (particularly in the dwarf regime) is a powerful calibrator for the processes that regulate star formation in galaxy formation models.

Evolution of Starless Cores in Massive Clumps Seen by the ALMA ASHES and QUARKS Surveys

First Author: Yang, Dongting
Instruments: ALMA_Band_6
ProgramIDs: 2021.1.00095.S
BibCode: 2026ApJ..1006..231Y

We present a systematic comparative analysis of 324 starless cores in early-phase infrared-dark clouds (IRDCs; ASHES survey) and evolved-phase infrared-bright clouds (IRBCs; QUARKS survey) using 1.3 mm continuum and line data by the Atacama Large Millimeter/submillimeter Array. Despite having comparable sizes (∼2500 au), starless cores in IRBCs exhibit systematically higher median mass (1.5 M_⊙ versus 0.6 M_⊙), number density, and surface density—enhancements of approximately a factor of 2 relative to starless cores in IRDCs. Starless cores in IRBCs also display relatively stronger nonthermal motions (σ ∼ 0.5 km s⁻¹ versus 0.3 km s⁻¹), higher total virial parameters (median α_vir,tot ∼ 2.3 versus 1.0), and steeper density profiles, indicating more centrally concentrated structures in feedback-driven, turbulence-enhanced environments. These findings support a dual evolutionary origin: (i) new core formation in evolved IRBCs under altered initial conditions and (ii) subsequent dynamical mass growth via accretion from extended reservoirs. The prevalence of low-mass starless cores—even in late-stage IRBC environments—challenges models requiring massive prestellar cores and instead favors competitive-like dynamical mass accretion scenarios for high-mass star formation.

Fragmentation of Massive Clumps: Constant Mass Fraction and Growing Mass Inequality of Cores

First Author: Lu, Zu-Jia
Instruments: ALMA_Band_6
ProgramIDs: 2019.1.00195.L
BibCode: 2026ApJ..1006..169L

The fragmentation of massive molecular clumps into dense cores sets the initial conditions for stellar clusters, yet how core mass distributions evolve remains unclear. Using the ALMAGAL survey (1013 clumps and 6348 cores), we analyze the Gini coefficient of core mass distributions for the 514 clumps containing at least four cores (N_frag ≥ 4), which host 5728 cores in total. We find that the most massive core consistently accounts for ∼38% of the total core mass ( fcore,max≍0.38 ), with no systematic trend with the total mass of the core per clump Mcore,tot . The Gini coefficient increases with total core mass ( Mcore,tot , r = 0.55) and evolutionary stage (L/M, r = 0.38). Clumps with L/M > 6.0 have significantly higher Gini values (median 0.62) than those with L/M ≤ 6.0 (median 0.49; p = 4.23 × 10⁻¹⁵). These results demonstrate that while the mass fraction of the most massive core is constant, overall mass inequality among cores grows systematically as clumps evolve.

Formation of a Protostellar Multiple System via Rotational Fragmentation

First Author: Liu, Tie
Instruments: ALMA_Band_6
ProgramIDs: 2018.1.00302.S
BibCode: 2026AJ....172..108L

We present a multiscale analysis of the dense core G205.46-14.56-N2 and its host filament G205.46-14.56 using ALMA, Herschel, JCMT, and PMO observations. The filament exhibits a hierarchical fragmentation process primarily governed by thermal Jeans instability. The central region of the dense core G205.46-14.56-N2 hosts a remarkable mirror-symmetric twin binary protostellar system. We detect well-collimated, aligned outflows from all four protostars. Velocity fields traced by H₂CO emission reveal clear gradients, and the ratio of rotational kinetic energy to gravitational energy increases with spatial resolution, indicating fast differential rotation within the core. The morphology and kinematics of the quadruple system bear striking resemblance to pure hydrodynamic simulations of rapidly rotating core collapse. These findings (ordered fragmentation and aligned outflows) are inconsistent with the stochastic expectations of turbulent fragmentation and instead may provide direct observational evidence that rotation-driven fragmentation is a viable pathway for forming compact protostellar multiple systems. To our knowledge, this study presents the first high-order (N ≥ 4) protostellar multiple system whose formation can be attributed to rotational fragmentation.

JWST+ALMA Reveal the Interstellar Medium Kinematics and Stellar Structure of MAMBO-9, a Merging Pair of DSFGs in an Overdense Environment at z = 5.85

First Author: Akins, Hollis B.
Instruments: ALMA_Band_7
ProgramIDs: 2021.1.00505.S
BibCode: 2026ApJ..1006..229A

We present high-resolution Atacama Large Millimeter/submillimeter Array (ALMA) [C II] 158 μm observations and JWST/NIRCam+MIRI imaging of MAMBO-9, a pair of optically dark, dusty star-forming galaxies at z = 5.85. MAMBO-9 is among the most massive, gas-rich, and actively star-forming galaxies at this epoch, when the Universe was less than 1 Gyr old. The new 400 pc resolution [C II] observations reveal velocity gradients in both objects; we estimate the dynamical masses and find a relative mass ratio of 1:5. The kinematics of both objects suggest both rotation and strong tidal interaction, suggesting that the pair has already experienced a close encounter. Indeed, the new JWST imaging reveals a continuous bridge of moderately dust-obscured material between the two. We perform spatially resolved spectral energy distribution (SED) fitting using the high-resolution ALMA+JWST imaging, finding that the majority of the recent star formation is concentrated in extremely obscured (A_V > 10) clouds, while the majority of the rest-optical light (stellar continuum and Hα emission) is emergent from moderately to highly obscured (A_V ∼ 1─5) regions on the outskirts. Combining our new stellar and dynamical mass measurements with previous CO observations, we find that the mass budget of MAMBO-9 requires a CO-to-H₂ conversion factor (α_CO) of order unity (∼1─2), indicative of a highly metal-enriched interstellar medium. Finally, we show that MAMBO-9 resides in a large overdensity spanning the PRIMER-COSMOS field, with 39 galaxies spectroscopically confirmed within ∼25 cMpc. With a total baryonic mass of ∼10¹¹ M_⊙, MAMBO-9 can be considered a prototype of massive galaxy formation and a likely progenitor of the brightest cluster galaxies in the lower-redshift Universe.

Spectroscopic analysis of RGB stars in nine open clusters

First Author: de Oliveira Cantanhêde, Saulo
Instruments: CRIRES
ProgramIDs: 089.D-0716
BibCode: 2026MNRAS.550g1103D

Stellar clusters are crucial tools for studying the age, spatial distribution, dynamics, kinematics, and chemical composition of different Galactic stellar populations. In this work, we used red giant stars from open clusters to better understand the extra-mixing process through the carbon, nitrogen, and oxygen (CNO) abundances and

$^{12}$

$^{13}$

$^{16}$

$^{17}$

O and

$^{16}$

$^{18}$

O isotopic ratios determined using high-quality spectra in the visible and near-infrared regions. We analysed the radial velocities and chemical composition of 22 K-type giant stars from nine open clusters (NGC 188, NGC 2682, NGC 3680, NGC 5822, IC 4756, NGC 6633, NGC 3532, NGC 6281, and NGC 5460). High-resolution and high signal-to-noise spectra of stars in the NGC188 cluster were obtained with the ESPaDOnS spectrograph at the Canada─France─Hawaii Telescope in the visible region. The stars in the other clusters were observed with the CRIRES spectrograph at the VLT. We used IRAF to compute radial velocities and TURBOSPECTRUM and MOOG for the chemical analysis. The values obtained for the radial velocities and abundances of the sample are similar to those found in the literature. The results in the visible and infrared support the occurrence and predicted mass dependence of thermohaline mixing on the red giant branch and of rotation-induced mixing on the main sequence. Variations of the initial abundances of

$^{17}$

O and

$^{18}$

O may be needed to explain the dispersion of the oxygen isotopic ratios in red giant stars.

The Structure of an 80 Parsec Long Massive Filament

First Author: He, Qian-Ru
Instruments: PI230
ProgramIDs: 095.C-0905
BibCode: 2026AJ....171..234H

Using new Institut de Radioastronomie Millimétrique 30 m telescope N₂H⁺, C¹⁸O J = 1─0 and Atacama Pathfinder Experiment telescope ¹³CO and C¹⁸O J = 2─1 maps together with archival far-infrared continuum data, and ¹²CO, and ¹³CO J = 1─0 data, we present a comprehensive analysis of the massive filament CFG024.00+0.48 (G24) across clump-to-cloud scales. Our results show that G24 is an ∼80 pc giant filament with a total mass of ∼10⁵ M_⊙. In the different tracers the filament width is measured to be about ∼2 times the beam size of the observations, as expected for power-law density distributions, giving beam-deconvolved widths in the range from 0.8 to 2.8 pc. We determine a line-of-sight thickness of ∼2.2 pc demonstrating that G24 is not an edge-on, flattened structure. The virial parameter obtained from line mass (α_line,vir = M_line,vir/M_line) from the C¹⁸O (1─0) data is 0.85, and that obtained from Herschel-based H₂ column density is 0.52, suggesting G24 is globally close to virial equilibrium. The distribution of the 40 dust clumps appears to have a "two-tier" fragmentation pattern. For the clump groups, the separation, with a mean/median of 3.68/3.46 pc, is very close to expected length associated with the maximum fragmentation growth rate of λmax=3.55±0.32 pc estimated for the dust. However, the longitudinal centroid velocity profiles of C¹⁸O and N₂H⁺ show oscillation patterns with wavelengths of 9.8 ± 0.1 pc and 9.9 ± 0.1 pc, respectively. This is ∼2 times larger than the corresponding values of λmax of 4.96 ± 0.63 pc and 4.65 ± 1.34 pc, respectively. This suggests that the velocity structure is not dominated by flows directly associated with the fragmentation seen in the dust emission.

A comprehensive catalogue of high-mass X-ray binaries in the Large Magellanic Cloud detected during the first eROSITA all-sky survey

First Author: Kaltenbrunner, D.
Instruments: FLAMES, GIRAFFE, VIRCAM
ProgramIDs: 179.B-2003, 082.D-0575, DataDoiProID
BibCode: 2026A&A...707A.225K

Context. The Magellanic Clouds, the closest star-forming galaxies to the Milky Way, offer an excellent environment to study high-mass X-ray binaries (HMXBs). While the Small Magellanic Cloud (SMC) has been thoroughly investigated with over 120 systems identified, the Large Magellanic Cloud (LMC) has lacked a complete survey due to its large angular size. Most prior studies targeted central or high-star-formation regions. The SRG/eROSITA all-sky surveys now enable a comprehensive coverage of the LMC, particularly due to its close vicinity to the south ecliptic pole. Aims. This work aims to improve our understanding of the HMXB population in the LMC by building a flux-limited catalogue. This allows us to compare sample properties with those of HMXB populations in other nearby galaxies. Methods. Using detections during the first eROSITA all-sky survey (eRASS1), we cross-matched X-ray positions with optical and infrared catalogues to identify candidate HMXBs. We assigned flags based on multi-wavelength follow-up observations and archival data, using properties of known LMC HMXBs. These flags defined confidence classes for our candidates. Results. We detect sources down to X-ray luminosities of a few 10³⁴ erg s⁻¹, resulting in a catalogue of 53 objects, including 28 confirmed HMXBs and 21 new eROSITA detections. Compared to the SMC, the LMC hosts fewer HMXBs and more systems with supergiant companions. We identify several likely supergiant systems, including a candidate supergiant fast X-ray transient with phase-dependent flares. We also find three Be stars with likely white dwarf companions. Two of the candidate Be/WD binaries show steady luminosities across four eROSITA scans, unlike the post-nova states seen in the majority of previous Be/WD reports. Conclusions. Our catalogue is the first to cover the entire LMC since the ROSAT era, providing a basis for statistical population studies. Using the HMXB population, we estimate the LMC star-formation rate to be (0.22_−0.07^+0.06) M_⊙yr⁻¹, which is in agreement with results using other tracers.

A super-Earth orbiting the early-M dwarf GJ7

First Author: Zapatero Osorio, M. R.
Instruments: ESPRESSO
ProgramIDs: 1102.C-0744, 1104.C-0350, 0103.C-0849, 106.21M2, 108.2254
BibCode: 2026A&A...706A.166Z

We aim to characterize the nearby (23.78 pc), low-mass planetary system GJ7 (TOI-198), which consists of an M0-type star and a terrestrial planet. Using photometric data from three sectors of the Transiting Exoplanet Survey Satellite (TESS) and a follow-up on the planetary transit observed by the Characterizing ExOPlanets Satellite (CHEOPS), along with 87 precise radial velocities obtained with the Echelle SPectrograph lor Rocky Exoplanets and Stable Spectroscopic Observations (ESPRESSO) spectrograph, we confidently confirm the planet and infer its properties. Planet GJ7 b has a mass of M_p = 3.17_−0.65^+0.64 M_⊕ and a radius of R_p = 1.36 ± 0.13 R_⊕. It orbits at a distance of a = 0.0675_−0.0082^+0.0067 au from its host star with an orbital period of P = 10.215213_−0.000010^+0.000011. We impose a 3σ upper limit on the planetary eccentricity of e ≤ 0.15. These parameters imply that GJ7 b has a high density, ρ_p = 6.89_−2.78^+4.27 gcm⁻³, positioning it within the region of the rocky, Earth-like planets on the mass─radius diagram and interior to the inner edge of the habitable zone around its parent star. Additionally, we find that the host star is a slow rotator and is slightly metal-depleted ([Fe/H] = −0.66 ± 0.10 dex), making GJ7 one of the lew planetary systems accurately characterized in the domain of subsolar iron abundances. TESS photometry does not show additional transit-like features attributable to planets with radii greater than ≍90% that of Earth. The high number of radial velocity measurements enables us to determine that possible transiting and non-transiting planet candidates with masses lower than hall the mass of GJ7 b would have eluded detection in our in-depth study. The stellar activity, although moderate, shows a significant radial velocity amplitude of about 4 ms⁻¹ and poses a challenge lor detecting planets with masses lower than Earth around GJ7.

Long-term eclipse time variations in white dwarf binaries

First Author: Yates, Amalie
Instruments: ULTRACAM_NTT
ProgramIDs: unknownID
BibCode: 2026MNRAS.547ag358Y

The overwhelming majority of eclipsing white dwarf (WD) binary systems show quasi-periodic variations in eclipse timings on many year time-scales. Currently, the mechanism behind these eclipse time variations (ETVs) is not known, with the main competing theories being the planetary hypothesis and the Applegate/Lanza mechanisms. Here, we present a comprehensive study of 43 WD binary systems, the vast majority of which have more than a decade of eclipse timing measurements, analysing their global properties to determine which driving force is the likely origin of the observed ETVs. Long-term, high-speed photometry data obtained with ULTRACAM, ULTRASPEC, and HiPERCAM have allowed us to track the evolution of the ETVs in these systems, and analyse any previously unseen trends. From this analysis, we find a clear difference in the level of observed ETVs past the fully convective boundary, where systems with partially radiative companion stars consistently showing high levels of variation. While some systems may be affected by the presence of an unknown planet, the results from this study strongly indicates that an Applegate- or Lanza-like mechanism is the most likely driving force for the timing variations seen in the majority of systems in this sample. However, as found in previous studies, the Applegate/Lanza mechanisms are still not able to reproduce the large and rapid timing variations seen in the vast majority of systems, with the companion star to the WD unable to provide sufficient energy on these short time-scales.

Follow-up of three exocomet-host candidates

First Author: Munoz-Cutanda, P.
Instruments: PIONIER
ProgramIDs: 093.C-0712
BibCode: 2026A&A...707A.166M

Context. Exocomets are small bodies that evaporate when they approach their host star. They can be detected based on the variability of non-photospheric features using spectroscopy and/or asymmetric transits in time-series photometry. Over the past four decades, about 30 systems have exhibited such variations and have therefore been classified as exocomet host stars. However, some recent publications have pointed out mechanisms that might mimic exocometary features. Therefore, careful monitoring is needed to confirm the origin of the observed variability. Aims. In this paper, we aim to investigate the exocomet nature of the non-photospheric variable features observed in the exocomet candidate stars HD 36546, HD 42111, and HD 85905. All of them have shown some degree of variability, particularly in their Ca II K line. Methods. We analysed the non-photospheric Ca II K line features from high-resolution spectra obtained using new NOT/FIES and Mercator/HERMES, along with some additional archival spectra of the target stars. The variability was quantified through the changes in the equivalent widths of those features, which are assumed to be of circumstellar origin. The column densities were also estimated for each variable feature. Results. Strong variability was found for HD 85905, consistent with a potential link to exocometary activity. However, the binarity of the system, which we confirmed through interferometric VLTI/PIONIER observations, complicates the interpretation of these signatures and prevents us from drawing definitive conclusions. The remaining two sources do not show any significant variability, but due to the sporadic nature of the exocometary events, we cannot discard the exocomet hypothesis. Further monitoring of the stars will be necessary to carry out a robust determination of the variability patterns and timescales that would completely rule out other scenarios.

The ALMA-ATOMS Survey: Methanol Emission in a Large Sample of Hot Molecular Cores

First Author: Zou, Jiahang
Instruments: ALMA_Band_3
ProgramIDs: 2019.1.00685.S
BibCode: 2026ApJ..1000...85Z

Methanol (CH₃OH) is a key complex organic molecule (COM) in the interstellar medium, widely used as a tracer of dense gas and hot molecular cores (HMCs). Using high-resolution Atacama Large Millimeter/submillimeter Array observations from the ATOMS survey, we investigate the excitation and abundance of methanol nuclear spin isomers and their relationship to chemical complexity in massive star-forming cores. We identify 20 methanol transitions, including A- and E-type lines in the v = 0 state and E-type lines in the v_t= 1 state, and detect 94 HMC candidates. Rotational temperature analysis under the LTE assumption yields average values of 194 ± 33 K for CH₃OH-E v_t= 1, 178 ± 33 K for CH₃OH-A v = 0, and 75 ± 21 K for CH₃OH-E v = 0. Emission from COMs other than methanol is detected in 87 of the 94 cores, with the CH₃OH-E v_t= 1 line intensity showing a strong correlation with the channel detection ratio (CDR). These results demonstrate that CH₃OH-E v_t= 1 lines are reliable tracers of HMCs and chemical complexity, and that the CDR provides a robust indicator of molecular richness. The temperature difference between A- and E-type methanol transitions is driven by anomalously strong J(2,J-2)−J(-1,J-1) lines, highlighting the importance of analyzing methanol symmetry types separately.

Simple cyanides and formylium ion isotopologues in early star-forming molecular cores

First Author: Taboada, R. D.
Instruments: ALMA_Band_7
ProgramIDs: 2017.1.00914.S
BibCode: 2026A&A...711A.129T

Aims. Understanding the chemistry related to the early stages of star formation is of great importance, as it is linked to the beginnings of the most complex chemistry in the interstellar medium. In this context, we investigate the chemical behaviour of simple cyano-bearing molecules and formylium ion isotopologues in a sample of massive infrared-quiet molecular cores. Methods. Using archive ALMA Band 7 data of 37 early molecular cores embedded in ATLASGAL clumps, we obtain abundances of HC₃N, H¹³CN, HN¹³C, H¹³CO°, and HC¹⁷O°. We used various statistical methods, including hierarchical clustering, to analyse the correlations between molecular abundances, ratios and temperature. Results. We find that the abundances of HN¹³C, H¹³CO°, and HC¹⁷O° positively correlate with the kinetic temperature, suggesting temperature-driven chemical regulation in young massive cores. A similar trend is observed for H¹³CN, although the limited number of detections prevents a definitive conclusion. The abundances of HC₃N show no dependence on temperature within the 40─100 K range, suggesting a chemical steady state between gas-phase production and grain-surface depletion. Similarly, the H¹³CN/HN¹³C ratio, measured in only six regions, suggests that there is no correlation with temperature, which differs from the findings at lower temperatures. Using a hierarchical clustering method based on abundance ratios, novel in astrochemistry, we identified chemically distinct core groups that align with thermal conditions. Additionally, we provide HC¹⁷O° detections for 28 cores ─ a significant expansion of the existing literature ─ and find evidence that H¹³CO° transitions may have higher optical depths than commonly assumed. These results are important because characterizing the chemical state of early star-forming stages is essential to understand the onset of the most complex chemistry.

A Merger within a Merger: Chandra Pinpoints the Short GRB 230906A in a Peculiar Environment

First Author: Dichiara, S.
Instruments: FORS2, HAWKI, MUSE
ProgramIDs: 110.24CF, 114.27LW
BibCode: 2026ApJ...999L..42D

We report the precise X-ray localization of GRB 230906A, a short-duration (T₉₀ ∼ 0.9 s) gamma-ray burst (GRB) with no optical or radio counterpart. Deep imaging with the Hubble Space Telescope detects a faint galaxy (G^*; F160W ≃ 26 AB mag) coincident with the subarcsecond X-ray position. Compared with standard GRB galaxies, its faintness, compact size, and color would suggest a high-redshift (z ≳ 3) host. However, our observations also reveal the presence of a galaxy group at z ∼ 0.453, confirmed spectroscopically with the Very Large Telescope/MUSE, with clear signs of interactions and mergers among group members. The GRB and its putative host project onto an extended (≍180 kpc) tidal tail emerging from the group's central galaxy. The probability of a chance alignment is small (P_cc ≲ 4%); we thus argue that the GRB and its galaxy G^* reside within the group. Their peculiar location along the tidal debris suggests that an enhanced burst of star formation, induced by the galaxy merger, might have formed the progenitor compact binary ≲700 Myr ago. The compact binary later evolved in a neutron star merger that produced GRB 230906A and injected r-process material into the surrounding circumgalactic medium.

ALMAGAL: IX. The chemical complexity of AG318.9477−00.1960: A line-identification template for ALMAGAL

First Author: Allande, J.
Instruments: ALMA_Band_6
ProgramIDs: 2019.1.00195.L
BibCode: 2026A&A...711A.118A

Context. High-mass star-forming regions are rich in complex organic molecules (COMs), which are carbon-bearing species with at least six atoms. Their formation pathways remain debated. The ALMA evolutionary study of high-mass protocluster formation in the GALaxy (ALMAGAL) survey provides a unique opportunity to probe this chemical complexity in a large statistical significant sample of high-mass star-forming regions. Aims. We present a detailed molecular line analysis of one of the most chemically rich cores in the ALMAGAL sample, the high-mass core 9 in the AG318.9477−00.1960 clump (AG318−c9), located at a heliocentric distance of ∼10.4 kpc. This source was selected because it combines an exceptionally high line density with a relatively simple kinematic structure, making it an optimal template for chemical analysis in the survey. We further assessed whether the emission of selected COMs, that is, ethylene glycol ((CH₂OH)₂; EG), glycolaldehyde (CH₂(OH)CHO; GA), and methyl formate (CH₃OCHO; MF), can be used to trace the innermost regions of hot molecular cores (HMCs). Methods. We analysed ALMA Band 6 observations (∼217─221 GHz). Spectral line identification and local thermodynamic equilibrium modelling were performed using the software called MAdrid Data CUBe Analysis (MADCUBA). We derived the physical parameters, including the column density (N), excitation temperature (T_ex), velocity, line width, and molecular abundances relative to H₂, for all detected species. The chemical inventory of AG318−c9 was compared with that of the HMC G31.41 + 0.31 (G31). In addition, we performed a pixel-by-pixel analysis of EG, GA, and MF to generate spatially resolved N and T_ex maps and corresponding radial profiles. Results. We report the detection of 65 molecular species, including 31 main species and 34 isotopologues and vibrationally excited species. Of these, 44 are O-bearing species, 28 are N-bearing, 8 are S-bearing, and 2 are Si-bearing. While AG318−c9 exhibits lower abundances than G31 overall, it shows detections of species that have not yet been reported in G31, such as ethyl formate (C₂H₅OCHO). Moreover, 12 species depart from the general trend, displaying relative overabundances in AG318−c9. The comparison also reveals a chemical differentiation between O- and N- bearing COMs, with O-bearing species systematically more abundant in G31. Regarding EG, GA, and MF, the latter is the most abundant (X ∼ 3 × 10⁻⁸), followed by EG (X ∼ 7 × 10⁻⁹) and GA (X ∼ 2 × 10⁻⁹). The N and T_ex maps suggest that MF is the most spatially extended species, whereas EG and GA are more compact and confined to the innermost hot region. Conclusions. AG318−c9 reveals a rich chemical inventory characteristic of an HMC. The chemical comparison with G31 suggests that AG318−c9 is a less evolved hot core dominated by the recent sublimation of ice mantles, in contrast to the higher abundances observed in the possible more evolved G31. MF emerges as an excellent tracer of the gas temperature in HMCs owing to its wide spatial extent and wide dynamic range of the excitation temperature. In contrast, EG and GA are more compact and preferentially trace the innermost high-density regions of the core, suggesting a high sublimation temperature threshold and supporting a shared grain-surface formation pathway. While EG and MF seem to be partly limited by sensitivity, GA reflects an intrinsically central distribution.

Infrared emission from z ∼ 6.5 quasar host galaxies: a direct estimate of dust physical properties

First Author: Costa, M.
Instruments: ALMA_Band_3, ALMA_Band_4, ALMA_Band_5, ALMA_Band_6, ALMA_Band_7, ALMA_Band_8
ProgramIDs: 2019.1.00147.S, 2019.2.00053.S, 2021.2.00064.S, 2021.2.00151.S, 2022.1.00321.S, 2023.1.01450.S, 2024.1.00071.S
BibCode: 2026A&A...706A.285C

Quasars at the dawn of cosmic time (z > 6) are fundamental probes for investigating the early coevolution of supermassive black holes and their host galaxy. Nevertheless, their infrared spectral energy distribution currently remains poorly constrained because the photometric coverage that probes the far-infrared wavelength range in which the dust modified blackbody is expected to peak (∼80 μm) is limited. We studied the high-frequency dust emission via a dedicated ALMA Band 8 (∼400 GHz) campaign targeting 11 quasar host galaxies at 6 < z < 7. Combined with archival observations in other ALMA bands, this program enables a detailed characterization of their infrared emission, which allowed us to derive dust masses (M_d), dust emissivity indexes (β), dust temperatures (T_d), infrared luminosities (L_IR), and associated star formation rates (SFRs). Our analysis confirmed that dust temperature is higher in this sample (34−65 K) than in local main-sequence galaxies, and this finding can be linked to the increased star formation efficiency we derived, as also suggested by the [CII]_{158 μm} deficit. Most remarkably, we note that the average value of T_d of this sample does not differ from the one that is observed in luminous, ultraluminous and hyperluminous infrared galaxies at different redshifts that show no signs of hosting a quasar. Finally, our findings suggest that the presence of a bright AGN does not significantly bias the derived infrared properties, although further high frequency observations with a high spatial resolution might reveal more subtle effects on subkiloparsec scales.

RedDots: Magnetic field of the nearby active M dwarf GJ 729, and a search for companions

First Author: Brown, E. L.
Instruments: HARPS
ProgramIDs: 099.C-0880, 072.C-0488, 097.C-0864
BibCode: 2026MNRAS.550g1294B

M dwarfs are prime targets for discovering exoplanets, and the nearest M dwarfs to the Sun provide among the best opportunities for follow-up detailed exoplanet characterization. GJ 729, the seventh closest M dwarf to the Sun, presents significant challenges for exoplanet detection due to its high levels of magnetic activity. To address this, we present a detailed analysis of GJ 729's magnetic field and its variability, followed by a search for exoplanets beneath the activity-induced noise in the stellar radial velocity. The geometry of GJ 729's large-scale magnetic field was reconstructed using new and archival spectropolarimetric data for a total of four epochs spanning 10 yr. Results indicate a weak large-scale field ranging from 50 to 145 G, and an evolving non-axisymmetric field geometry that varies from poloidal dominated to a near-equal poloidal-toroidal configuration. We modelled activity-induced radial velocity variations using Gaussian Process Regression and activity diagnostics, and searched for planetary companions using

${\sim} 90$

d of high-cadence spectra taken contemporaneously with the high-precision CARMENES and HARPS spectrographs. Activity-only and activity + Keplerian models offered statistically equivalent fits, with a consistently preferred Keplerian period of

${\sim} 7$

d and amplitude of

${\sim} 1.9\rm {\, m\, s}^{-1}$

across a range of activity modelling approaches. This could relate to an Earth-mass or Super-Earth planet, or residual stellar activity with power concentrated at a multiple of the rotation half-period. Our findings provide insight into the magnetic behaviour of fully convective M dwarfs, and highlight the potential and challenges of detecting Keplerian RV signatures that are only a fraction of activity amplitudes.

Kinematical and dynamical properties of recently discovered bulge and disc star clusters with WINERED

First Author: Petralia, Ilaria
Instruments: VIRCAM
ProgramIDs: 179.B-2002, 198.B-2004
BibCode: 2026A&A...707A..83P

Context. Galactic globular clusters are a very important tool in explaining the characteristics of the Milky Way. Therefore it is essential to determine the kinematical and dynamical properties of the new star cluster candidates, especially at the low-latitude regions that suffer from heavy extinction and crowding. Aims. In this work, we report the first spectroscopic analysis for seven recently identified star cluster candidates: CWNU 4193, FSR 1700, Garro 02, Patchick 98, FSR 1767, Mercer 08, and BH 140. Our aim is to determine the kinematical properties, such as the mean cluster radial velocity, and the dynamical properties, such as the orbital parameters and the global dynamical mass, of these clusters in order to spectroscopically confirm the nature of these seven stellar systems. Methods. We collected the high-resolution infrared spectra of 33 candidate members of these clusters using the WINERED spectrograph mounted on the Magellan Clay 6.5 m telescope. Using the WINERED spectra, we measured the radial velocity of each individual star to confirm its membership in the clusters. From the confirmed members, we derived the mean cluster radial velocity of each cluster. In addition, for these clusters, we computed the orbital elements using the GravPot16 model and estimated their global dynamical masses based on the virial theorem. Results. As a result, we confirmed enough member stars (from three to seven stars per cluster) to reliably derive the mean cluster radial velocity and compute the orbital parameters of the clusters CWNU 4193, FSR 1700, Garro 02, and BH 140. For clusters CWNU 4193, FSR 1700, and BH 140, the number of confirmed members also allowed us to estimate their global dynamical masses. Therefore, we successfully derived key kinematical and dynamical properties for four of the most obscured star clusters in the Milky Way.

Unveiling the nature of SN 2022jli: The first double-peaked stripped-envelope supernova showing periodic undulations and dust emission at late times

First Author: Cartier, Regis
Instruments: EFOSC2, HAWKI
ProgramIDs: 382.B-0331, 108.220C
BibCode: 2026A&A...707A.161C

We present optical and infrared observations from maximum light until around +800 days of supernova (SN) 2022jli, a peculiar stripped-envelope (SE) SN showing two maxima, each one with a peak luminosity of about 3 × 10⁴² erg s⁻¹, separated by 50 days. The second maximum is followed by unprecedented periodic undulations with a period of P ∼ 12.5 days. The spectra and the photometric evolution of the first maximum are consistent with the behaviour of a standard SE SN with an ejecta mass of ∼1.5 M_⊙ and a radioactive ⁵⁶Ni mass of ∼0.12 M_⊙. The optical spectra after +400 days relative to the first maximum correspond to a standard SN Ic event, and at late times SN 2022jli exhibits a significant drop in the optical luminosity, implying that the physical phenomena that produced the secondary maximum have ceased to power the SN light curve. Among other potential scenarios, we discuss how the second maximum could be powered by a magnetar, while the light curve periodic undulations could be produced by accretion of material from a companion star onto the neutron star in a binary system. The near-infrared spectra shows clear first CO overtone emission from about +190 days after the first maximum, and it becomes undetected at +400 days. A significant near-infrared excess from hot dust emission is detected at +238 days, having been produced by either newly formed dust in the SN ejecta or a strong near-infrared dust echo. Depending on the assumptions of the dust composition, the estimated dust mass is 2 − 16 × 10⁻⁴ M_⊙. The potential magnetar power of the second maximum can fit into a more general picture in which magnetars are the power source of SE super-luminous SNe, and could explain bumps, undulations, and late-time excess emission in SE SNe. The CO detection and the dust emission of SN 2022jli are key to understanding the molecule and dust formation in the ejecta of SE SNe and in their environment.

Linking the morphology of young stellar objects to their evolutionary stages with self-organizing maps

First Author: Hernandez, David
Instruments: VIRCAM
ProgramIDs: 090.C-0797
BibCode: 2026A&A...707A..23H

Context. Many studies in the past few decades have investigated the evolution of young stellar objects based on their spectral energy distribution. This distribution is heavily affected not only by the evolutionary stage, but also by the morphology of the forming star. This study is part of the NEMESIS project, which aims to revisit star formation with the aid of machine-learning techniques and provides the framework for this work. Aims. In a first effort toward a novel spectro-morphological classification, we analyzed the morphologies of young stellar objects and linked them to the currently used observational classes. Thereby, we laid the foundation for a spectro-morphological classification and applied the insights learned in this study in a future revisited classification scheme. Methods. We obtained archival high-resolution survey images from VISTA for approximately 10000 young stellar object candidates from the literature toward the Orion star formation complex. Using a self-organizing map algorithm, which is an unsupervised machinelearning method, we created a grid of morphological prototypes from near- and mid-infrared images. Furthermore, we determined the prototypes that best represent the different observational classes we derived from the infrared spectral index via Bayesian inference. Results. We present our grids of morphological prototypes of young stellar objects in the near-infrared. The prototypes were created from observational data alone. They are thus independent of theoretical models. In addition, we show maps that indicate the probability for a prototype to belong to any of the observational classes. Conclusions. Self-organizing maps created from near-infrared images are a useful tool, with limitations, for identifying the characteristic morphologies of young stellar objects in different evolutionary stages. This first step lays the foundation for a spectro-morphological classification of young stellar objects that is to be developed in the future.

Evidence for the Merger Hypothesis in V4332 Sgr: A Low ¹²C/¹³C Ratio and Multiple Outbursts

First Author: Banerjee, D. P. K.
Instruments: UVES
ProgramIDs: 075.D-0511
BibCode: 2026ApJ...999L..35B

Following the detections of the first extragalactic "luminous red nova" (LRN) M31RV in 1989, and its first Galactic counterpart V4332 Sgr in 1994, there have been many discoveries of similar, or closely related, objects. They are important because they bridge the luminosity gap between the brightest novae and supernovae, a largely unexplored parameter space. The cause of eruptions in LRNe is still unclear, a stellar merger being the most favored mechanism. However, barring V1309 Sco, there has been no direct evidence for a merger in the other objects. Here we present strong evidence that V4332 Sgr was a merger event. High-resolution infrared observations of the CO fundamental band show an unusually small ¹²C/¹³C ratio of 3.5 ± 1. This indicates that a violent event had occurred, whose effects penetrated deep enough to allow the CNO cycle processed ¹³C in the inner H burning shell to be brought to the surface. We rule out planetary ingestion and propose that the eruption was due to a merger between V4332 Sgr and a companion star. It is shown that V4332 Sgr was likely surrounded by an edge-on disk before its eruption. If this disk was a flattened common envelope containing V4332 Sgr and a companion star, then a merger scenario would not be inconsistent. Furthermore, it is also shown that V4332 Sgr had multiple outbursts, previously unreported but an important piece of information, since multiple outbursts are a trait shared by many LRNe.

Galactic bars and active galactic nucleus fuelling in the second half of cosmic history

First Author: La Marca, A.
Instruments: OMEGACAM
ProgramIDs: 177.A-3016, 177.A-3017, 177.A-3018
BibCode: 2026A&A...707A.152L

We investigate the role of galactic bars in fuelling and triggering active galactic nuclei (AGN) in disc galaxies up to z ∼ 0.8. We utilised a deep learning model, fine-tuned on Galaxy Zoo volunteer classifications, to identify (strongly and weakly) barred and unbarred disc galaxies in Hyper Suprime-Cam Subaru Strategic Program i-band images. We selected AGN using three independent diagnostics: mid-infrared colours, X-ray detections, and spectral energy distribution (SED) fitting. The SED analysis, performed using CIGALE, quantifies the relative AGN contribution to the total galaxy luminosity (f_AGN) and the AGN luminosity (L_disc). We assessed the impact of bars by comparing AGN incidence and properties in barred galaxies against carefully constructed redshift-, stellar mass-, and colour-matched unbarred control samples. Our binary AGN classification experiment demonstrates that barred disc galaxies host a higher fraction of AGN compared to their unbarred counterparts, though the significance depends on the AGN selection method, with a more modest excess for SED AGN, and control sample size. This suggests a contributing role for bars in the global AGN budget. The contribution of bars to AGN fuelling appears confined to systems where the AGN has a lower relative contribution to the host galaxy's emission (f_AGN < 0.75). Crucially, we find a significant dearth of barred disc galaxies hosting AGN with f_AGN > 0.75, independent of bar strength. Consistent with this, the fraction of barred galaxies among AGN hosts decreases with increasing L_disc. Combined with previous results, we suggest that bars may contribute to fuelling the population of low-to-moderate-luminosity AGN, but major mergers are the principal mechanism for triggering the most powerful and dominant accretion events.

Physical properties of circumnuclear ionising clusters: IV. NGC 1097

First Author: Zamora, Sandra
Instruments: MUSE
ProgramIDs: 097.B-0640
BibCode: 2026A&A...711A.233Z

The circumnuclear star-forming ring of the barred spiral galaxy NGC 1097 provides a unique laboratory to study star formation under extreme conditions. In this work, we aim to derive the physical properties of the circumnuclear star-forming regions (CNSFRs) using MUSE integral field spectroscopy observations. We identified and analysed a total of 24 individual ionised HII within its ring, which spans from ∼385 pc to ∼1.3 kpc. Despite the complex nuclear activity, all HII regions were found to be purely photoionised. Directly derived abundances reveal supersolar metallicities, with the highest one exceeding five times the solar value (12+log(S/H) = 7.875 ± 0.353, T_e([SIII]) = 3912 ± 567 K) and representing the highest abundance reported to date. In this high-metallicity regime, we found a break in the ionisation parameter─[SII]/[SIII] relation, which can be explained by changes in the ionisation structure and line emissivities, as confirmed by photoionisation models that successfully reproduce the observed emission-line ratios. Our results also indicate that the local gas supply regulates the star formation activity within the ring, with the young stars ionising 8% of the total gas in the ring. Furthermore, our findings support a propagating starburst scenario originating in the galaxy nucleus and extending towards the ends of the bar and into the circumnuclear ring through bar-driven shocks, which is consistent with the results of previous multi-wavelength studies. Finally, we likely detected optical signatures associated with one of the two known jets in this galaxy. This finding, together with the radio core emission previously found at sub-parsec scales, reflects the presence of feedback processes operating even on small galactic disc scales.

Dust destruction signals shock-accelerated outflows in the nearby active galaxy NGC 1068

First Author: Holden, Luke R.
Instruments: XSHOOTER
ProgramIDs: 111.24FW
BibCode: 2026MNRAS.550g1183H

Massive gas outflows driven by active galactic nuclei (AGN) are a key ingredient in models of galaxy evolution, in which they are required to regulate star formation and thus explain the observed properties of the galaxy population. However, it remains uncertain how such outflows are accelerated. Here, we use deep spectroscopic observations of the nearby active galaxy NGC 1068 to directly address this issue. Based on the flux ratios of high-ionization [Ne V]

$\lambda$

3425 and [Fe VII]

$\lambda$

6087 coronal forbidden lines, we show that the non-outflowing gas in the disc of the galaxy is characterized by high levels of depletion of refractory elements on to dust grains, but the outflowing gas just above the disc is largely dust-free. Consistent results are also found for the ratios of lower ionization forbidden lines of refractory and non-refractory elements. Moreover, a range of diagnostic ratios demonstrate that the density of outflowing gas is a factor 19─110 times higher than that of the non-outflowing gas. Together, these results imply that the outflows in NGC 1068 are accelerated by fast shocks that both compress the gas and destroy much of the dust. Consistent with the idea that AGN-driven shocks play an important role in heating and accelerating the near-nuclear gas in galaxies, this study demonstrates that coronal emission lines are a key diagnostic of the destructive impact of AGN activity.

Chemical Abundances of the Bioessential Elements C, O, and S, and the Refractory Elements Fe and Ni, in Solar-type Exoplanet-hosting Stars from HARPS North and South

First Author: Costa-Almeida, Ellen
Instruments: HARPS
ProgramIDs: DataDoiProID
BibCode: 2026AJ....172...96C

We determined atmospheric and evolutionary parameters, along with chemical abundances of C, O, S, Fe, and Ni for 290 solar-type exoplanet-hosting stars using high-resolution HARPS-North and HARPS-South spectra, and radii for 373 exoplanets using literature transit depths. We find that stars hosting giant exoplanets (R_pl > 4 R_⊕) show enhanced [X/H] abundances compared to small exoplanet hosts for all elements analyzed. When considering only exoplanets with P_orb ≤ 30 days, there is a statistically significant anticorrelation between the host star [Fe/H] and P_orb. However, [Fe/H] does not continue to decline as the orbital period increases, but rather rises again for exoplanets with larger orbital periods. Stars hosting only small exoplanets or hosting at least one sub-Saturn show significant differences between the populations of hot and warm exoplanets for all elements. In contrast, stars hosting at least one Jupiter-sized planet show no abundance differences. The host star C/O ratios obtained vary from 0.17 to 0.95, with giant exoplanet hosts exhibiting the lowest median C/O ratios (0.43 −0.03+0.02 ), while the 3─4 R_⊕ sub-Neptune hosts in our sample exhibit the highest median C/O ratios (0.55 −0.01+0.05 ). Our sample has 199 exoplanets with estimated masses, and we find correlations between host star [O/H] and [S/H] and log(Mpl/M⊕) . When segregating the sample into hot and warm exoplanet hosts, these trends are only found for warm exoplanets. Dividing the sample between low- (91 exoplanets) and high-[α/Fe] (20 exoplanets) stars, there are trends between the host star [O/H], [S/H], [Fe/H], and [Ni/H] and log(Mpl/M⊕) only for the low-[α/Fe] sample.

ATREIDES: II. Detection of a polar orbit for HAT-P-26 b, a fluffy planet in the Neptunian ridge

First Author: Luo, X.
Instruments: ESPRESSO
ProgramIDs: 1104.C-0350, 106.21M2, 109.23FU, 112.25BG
BibCode: 2026A&A...711A.237L

Context. HAT-P-26 b is a well-characterized Neptunian exoplanet (R_p ≃ 6.33 R_⊕) orbiting a K1V star. It lies within the Neptunian ridge (P_orb ≃ 4.2345 days), following a moderately eccentric orbit (e ≃ 0.12) and hosting a water-rich atmosphere. The possible presence of a stellar companion hinted at by near-infrared (NIR) spectral emission, along with candidate planetary companions inferred from transit timing variations, calls for further investigations of the system architecture. Hence, the HAT-P-26 system is a prominent target for investigating the atmospheric and dynamical evolution of exo-Neptunes and, in particular, via the study carried out by the Ancestry, Traits, and Relations of Exoplanets Inhabiting the Desert Edges and Savanna (ATREIDES) collaboration. Aims. We combined three transit observations of HAT-P-26 b using ESPRESSO on ESO's VLT to precisely characterize its orbital architecture and to investigate whether it has a misaligned orbit, as reported in cases of other evaporating and eccentric planets in the ridge. Methods. We employed the ANTARESS workflow to perform a careful and robust data reduction. We explored the system's orbital architecture using the in-built Rossiter-McLaughlin Revolutions (RMR) technique. Results. HAT-P-26 b exhibits a polar orbit (projected obliquity angle of λ = −78₋₁₃^+13∘ and a 3D true obliquity angle of ψ = 85₋₅^+5∘). This places it alongside GJ 436 b, HAT-P-11 b, and GJ 3470 b as polar-orbit and eccentric planets lying within the ridge population. It has the lowest density (0.40 ± 0.10 g cm⁻³) of these four planets, placing it near the density brink where full atmospheric erosion after early disk-driven migration or tidal disruption after high-eccentricity migration has been proposed to occur. Our dynamical analysis suggests that the observed polar orbit might either be a transient state arising from orbital-plane precession or a relic of high-eccentricity migration via Von Zeipel─Lidov─Kozai cycles driven by an inclined stellar companion. We note that in the latter case, the existence of planet c would be strongly disfavored. Conclusions. HAT-P-26 b stands out as a special target in the Neptunian ridge, owing to its low density and polar orbit. The current dynamical analysis is limited by the uncertainties surrounding companion(s) in this system. As better constraints on the companion(s) become available, it will be particularly interesting to further explore the origin of this fluffy ridge Neptune through a joint analysis of migration, evaporation, tidal disruption, and inflation. Our results also demonstrate the importance of homogeneous data reduction when combining multi-epoch transit observations for accurate spin─orbit characterization.

CRIRES+ Reveals the Chemistry of the Stellar Subpopulations in the Bulge Fossil Fragment Liller 1

First Author: Chiappino, L.
Instruments: CRIRES
ProgramIDs: 109.230K, 110.24A4
BibCode: 2026ApJ..1006...32C

In this paper, we present the chemical screening of the complex stellar population discovered in the Bulge Fossil Fragment Liller 1. This study is part of the Bulge Cluster Origin (BulCO) survey based on a Large Program at the ESO-Very Large Telescope with the high-resolution spectrograph CRIRES+. The survey is aimed at performing an unprecedented chemical screening of 17 stellar systems orbiting the Milky Way bulge, with the ultimate goal of unveiling their origin and true nature. We measured precise chemical abundances of iron, CNO, iron-peak, α-elements, a few other light elements, and neutron-capture elements for a sample of 30 red giant branch stars, kinematic members of Liller 1. The presented analysis provides the high-resolution spectroscopic proof of the complex chemistry of this massive stellar system, with multimetallicity subpopulations of different ages that nicely fit into a self-enrichment scenario. We find no evidence for the Na─O anticorrelation associated with genuine globular clusters; rather, the overall abundance trends are similar to those seen in the bulge field and in Terzan 5, providing definitive evidence of an in situ formation of Liller 1 within the Galactic bulge. *Based on observations collected at the Very Large Telescope of the European Southern Observatory at Cerro Paranal (Chile) under program 109.230K and Large Program 110.24A4 (PI: Ferraro).

VLT/CRIRES+ observations of warm Neptune WASP-107 b: Challenges in detecting molecules with ground-based transmission spectroscopy of cooler and cloudy exoplanets

First Author: Boldt-Christmas, L.
Instruments: CRIRES
ProgramIDs: 110.249Y, 60.A-9051, 108.22PH
BibCode: 2026A&A...711A.254B

Context. The atmospheres of transiting exoplanets can be studied spectroscopically using space-based or ground-based observations. Each has its own set of strengths and weaknesses, so there are benefits to both approaches. This is especially true for more challenging targets such as cooler, smaller exoplanets whose atmospheres most likely contain many molecular species and cloud decks. Aims. We aim to study the atmosphere of the warm Neptune-like exoplanet WASP-107 b (T_eq ≍ 740 K). Several molecular species have been detected in this exoplanet in studies using the space-based JWST, and we aim to confirm and expand upon these detections by using the ground-based VLT and evaluating how well our findings agree with previously retrieved atmospheric parameters. Methods. We observed two transits of WASP-107 b with VLT/CRIRES⁺ and created cross-correlation templates of the target atmosphere based on results from previous studies. We created different templates to investigate the impact of varying volume mixing ratios of species and the inclusion or exclusion of clouds. Considering this target's observational challenges, we created simulated observations prior to evaluating our real data in order to assess our expected detection significances with the cross-correlation technique. Results. We report cross-correlation signals of two molecular species, CO (~6σ) and H₂O (~4.5σ), in our K_p − v maps. This supports previous space-based detections and demonstrates, for the first time, the capability of VLT/CRIRES⁺ to detect species in targets cooler than hot Jupiters using transmission spectroscopy. We show that our analysis is sensitive to the inclusion of clouds but less so to different volume mixing ratios. Interestingly, our signal maximum deviates notably but consistently from its expected location in the K_p direction of our maps, and we speculate on the possible reasons for this effect. We demonstrate that the error budget for these relatively cool exoplanets is severely reduced in comparison to hotter exoplanets and emphasise the need for further work in the context of high-resolution spectroscopy.

Determination of kinematic distances of WISE and SMGPS H II regions in the Galactic plane using SEDIGISM cloud association

First Author: Langa, Moses O.
Instruments: SHFI
ProgramIDs: 092.F-9315, 193.C-0584, Chilean data, Max-Planck data
BibCode: 2026MNRAS.550g1282L

One of the fundamental requirements for studying and understanding Galactic structure and massive star formation is accurate distances to H II regions. However, most distance assignments are hampered by kinematic distance ambiguity, sparse parallax measurements, and the large number of radio continuum sources lacking velocity and distance measurements. We present a kinematic distance determination method via cloud association, linking H II regions from the Wide-field Infrared Survey Explorer (WISE) catalogue and the South African Radio Astronomy Observatory MeerKAT Galactic Plane Survey with molecular clouds from the Structure, Excitation and Dynamics of the Inner Galactic Interstellar Medium (SEDIGISM)

$^{13}$

CO (2─1) survey. The associations are established through spatial overlap and velocity coherence, and the molecular cloud velocity and distance are then assigned to the associated H II region. The method yields 741 H II regions with adopted CO-based systemic velocities, of which 640 have reliable kinematic distances based on the SEDIGISM distance reliability criteria. We validate the method using 329 H II regions with independent radio recombination line (RRL) velocities, finding excellent agreement with a median absolute velocity difference of 3.46 km s

$^{-1}$

. Our analysis resolves ambiguous velocities for 40 H II regions with multiple WISE RRL velocity measurements. Compared to the unassociated clouds, the associated molecular clouds exhibit significantly higher masses, gas surface densities, linewidths, star formation efficiencies and dense gas fractions, and slightly lower virial parameters. This work provides a large, homogeneously derived catalogue of H II region distances and establishes a framework for further studying massive star formation and Galactic structure in general.

Spectroscopic metallicities and first α-element abundances of RR Lyrae stars in Baade's Window

First Author: Olivares Carvajal, J.
Instruments: FLAMES, GIRAFFE, VIRCAM
ProgramIDs: 179.B-2002, 198.B-2004, 093.B-0473
BibCode: 2026A&A...711A.288O

Context. The shape and kinematics of the metal-poor stellar component of the Galactic bulge are still poorly characterized, and, therefore, the origin of this component is not yet strongly constrained. RR Lyrae stars in the bulge have been reported to be associated with the spheroidal, relatively metal-poor component. They offer a way to trace this component with precise distances and therefore the possibility to calculate orbits and minimize contaminations. While a few studies of RR Lyrae spectra with medium and/or high resolution are now available, none target stars in the Galactic bulge. Aims. We present here a spectroscopic determination of Fe and α-element abundances for RR Lyrae stars in the Galactic bulge, with the main goal of providing a benchmark to calibrate other metallicity indicators, appropriate for this specific stellar population. Methods. We analyzed FLAMES/GIRAFEE spectra of 78 RR Lyrae stars (60 ab-type and 18 c-type). We applied a full-spectrum fitting technique to obtain the spectroscopic metallicity and overall α-element abundance. Distances were derived by means of a period─luminosity─metallicity relation, and orbits were computed by combining the radial velocities derived in our study with the proper motions from Gaia DR3. Results. The resulting metallicities peak at [Fe/H]_median = −1.34 ± 0.04 and −1.44 ± 0.08 dex for ab and c-types, respectively. The majority of the bulge RR Lyrae are metal-poor stars with relatively high α-element abundances around [α/Fe] ∼ 0.25 ± 0.03 dex. We used our spectroscopic measurements to test different methods for deriving metallicities based on photometry, which utilize Fourier parameters in the light curves of the RR Lyrae. The data suggest a possible correlation between the metallicity difference and the [α/Fe] ratio, which requires further investigation. There are some ab-type RR Lyrae that show metallicities higher than ─1 dex and low [α/Fe] values. We kinematically studied these stars and find a difference between three stars with similar [α/Fe] values and the main group, indicating that they may be slightly younger and correspond to the disk population.

JWST spectroscopy of SN 2010da/NGC 300 ULX-1: a surviving star hidden by dust

First Author: Beasor, Emma R.
Instruments: XSHOOTER
ProgramIDs: 109.22V5
BibCode: 2026MNRAS.550g1077B

We present new James Webb Space Telescope (

$JWST$

) NIRSpec and MIRI integral-field spectroscopy of the remarkable system SN 2010da/NGC 300 ULX-1, the only known ultraluminous X-ray source powered by a neutron star with a supergiant donor. Our new data, taken in 2024 November, reveal that the optical and near-infrared counterpart has dramatically faded since 2018 and no longer exhibits molecular absorption features characteristic of a red supergiant. Instead, the spectral energy distribution (SED) shows the donor has returned to its pre-outburst appearance, and is dominated by infrared continuum consistent with an optically thick warm (

$\approx$

900 K) dust shell. The bolometric luminosity indicates the presence of a surviving luminous source with

$\log (L/\mathrm{ L}_\odot)$

= 4.11

$\pm$

0.02. Radiative transfer modelling of the mid-infrared SED reveals a broad emission feature peaking near

$\sim$

11 μm, best reproduced by silicon carbide (SiC) dust grains, a composition typically associated with carbon-rich evolved stars. We rule out a failed supernova scenario, which would predict a large drop in luminosity and continued fading. Given the association of SiC dust with asymptotic giant branch (AGB) stars, we suggest the donor star may be an AGB star that has survived and is now heavily enshrouded ─ having returned to a dust-obscured state following a transient post-outburst phase in which the system appeared as a red supergiant. We propose a revised evolutionary timeline in which the 2010 outburst initiated sustained super-Eddington accretion and temporarily altered the circumstellar environment. These observations provide rare insight into eruptive mass-loss, dust formation, and binary interaction in a unique system.

Spectral Ratio Analysis: probing of a new suite of stellar activity indicators as a tool for astrophysical noise mitigation

First Author: Costes, Jean C.
Instruments: HARPS, NIRPS
ProgramIDs: 094.C-0797, 095.C-0040, 096.C-0053, 072.C-0096, 073.D-0038, 074.D-0131, 075.D-0194, 0100.C-0487, 091.C-0936, 072.C-0488, 090.C-0849, 092.C-0579, 60.A-9109, 106.215E, 105.20AK, 110.24BB, 097.C-0021, 082.C-0315, 0102.C-0525, 084.C-0229, 085.C-0318, 093.C-0062, 089.C-0050, 086.C-0230, 096.C-0499, 60.A-9709, 081.D-0065, 0103.C-0206, 196.C-1006, 083.C-1001, 0100.D-0444, 077.C-0530, 077.C-0364, 078.C-0833, 079.D-0075, 076.D-0130, 078.D-0071, 198.C-0836, 081.C-0842, 073.C-0784, 0101.C-0275, 0103.D-0445, 1102.C-0923, 079.C-0681, 192.C-0852, 0102.C-0584, 099.C-0491, 185.D-0056, 183.C-0972, 188.C-0265, 183.D-0729, 074.C-0012, 60.A-9036, 076.C-0878, 072.C-0513, 080.D-0086, 087.C-0990, 088.C-0011
BibCode: 2026MNRAS.550g1173C

Stellar activity is the main barrier to detecting and/or confirming low-mass/long-period (and Earth-analogue) planets using radial-velocity (RV) measurements. Searching for reliable indicators that better trace magnetic activity may be key for both distinguishing more clearly between stellar and planetary signals, and for probing the underlying physics occurring on the stellar surface. In this work we have compared observations taken for magnetically active and inactive stellar phases over multiple time-scales to study the spectral imprint due to varying stellar activity. This serves as a proof-of-concept demonstration of a technique (named Spectral Ratio Analysis, SRA) that can be used to isolate activity-driven changes directly in the stellar photospheric absorption lines where RVs are measured. Using 14 relatively quiet and well sampled G- and K-type stars that show stellar activity cycles, we identified hundreds of activity-sensitive spectral features. Reducing this variability information into two global metrics ─ amplitude and velocity shift ─ uncovers potential evidence of a decoupling of the photospheric and chromospheric responses to stellar activity in earlier-type stars. Additionally, potential signatures of the variations in the magnitude of the suppression of the convective blueshift throughout the activity cycle were observed via SRA. Finally, we show that these SRA indicators better capture RV variability than classical activity proxies, such as the chromospheric log

$R^{\prime }_\mathrm{HK}$

index and other cross-correlation function-based parameters such as bisector span and full width at half-maximum, by up to a factor of two. The direct link between photospheric line behaviour and stellar-induced RV variability offers a promising path for improving astrophysical noise mitigation.

¹³CO and potential variability in β Pictoris b with GRAVITY+

First Author: von Stauffenberg, A.
Instruments: GRAVITY
ProgramIDs: 114.27JS
BibCode: 2026A&A...711L...2V

The ¹²CO/¹³CO ratio was introduced as an indicator for where in the disk a planet has formed. Previously, a lower value compared to that of the host star was suggested to indicate that a planet accreted CO ice beyond the disk's CO ice line. In this Letter, we aim to determine the ¹²CO/¹³CO value of the directly imaged planet β Pictoris b and whether we can link it to its formation. Its apparent brightness results in an exceptional signal-to-noise ratio of up to ∼60 per wavelength point. We present the first science observations with the upgraded GRAVITY+ instrument at a spectral resolution of R ≍ 4000, which we analysed with petitRADTRANS. Our retrievals robustly indicate ¹³CO with a ¹²CO/¹³CO ratio of 91 ⁺²⁴₋₁₇ − 17 + 24 , consistent with both a solar to interstellar-medium-like value. Our ¹²CO/¹³CO value corroborates recent interpretations that ¹³CO may be a less useful tracer of formation location in the disk than previously thought; nonetheless, we discuss theories with which this value is consistent. As our observations span ≍7 hours, this enabled us to search for atmospheric variability in β Pictoris b; we report a tentative constraint on the variability amplitude of about 1.4 ^+0.6_−0.7 − 0.7 + 0.6 %.

TOI-159 b: An eccentric hot-Jupiter planet around a young, pulsating γ Doradus star

First Author: Mantovan, G.
Instruments: HARPS
ProgramIDs: 108.22LR
BibCode: 2026A&A...711A.107M

Fast-rotating hot stars are challenging targets for exoplanet searches due to rotational broadening and stellar variability. Moreover, hot stars often exhibit pulsations, an additional source of scatter in both photometric and spectroscopic series. Because of these challenges, such stars remain a relatively unexplored environment for planetary architecture and evolution studies. In this study, we present the confirmation and preliminary atmospheric characterisation of a giant planet orbiting a young (≍150 Myr), pulsating γ Doradus star. TOI-159 b (P_orb ≃ 3.7 d, R_p ≃ 1.6 R_J, M_p ≃ 3.5 M_J) is an S-type planet in a close binary system and is the hottest (T_eq ≃ 1900 K) hot Jupiter with a significant eccentricity (e = 0.24 ± 0.04) ever detected. Our joint modelling of radial velocities (HARPS and CORALIE), transits (TESS), and spectro-photometry (IMACS) allows us to detect its Keplerian signal at high significance (13σ), place strong constraints on its eccentricity (6σ), disentangle the stellar rotational modulation and pulsation periods, and generate a low-resolution transmission spectrum, on which we conduct an exploratory analysis to constrain the presence of a planetary atmosphere using combined star-planet retrievals. Whilst our spectrum appears to display some modulation, the data are too coarse to allow for any conclusive detections at this stage. Higher-resolution observations are needed to confirm or refute these features and, if genuine, determine whether they originate from contamination from the star or a planetary atmosphere.

Dust-embedded Star Formation: Bridging Magellanic Cloud Studies of Massive Young Stellar Objects to Nearby Spiral Galaxies

First Author: Rodríguez, M. Jimena
Instruments: ALMA_Band_6
ProgramIDs: 2017.1.00901.S, 2018.A.00058.S, 2018.A.00062.S
BibCode: 2026ApJ..1006..144R

We use JWST NIRCam and MIRI imaging at 2, 4, 10, and 21 μm to study young, dusty compact sources in four nearby galaxies at distances of ∼1─5 Mpc (M33, NGC 300, NGC 7793, and NGC 5068). This work bridges well-characterized massive young stellar objects (MYSOs) in the Magellanic Clouds from the Spitzer Space Telescope SAGE survey to new studies of embedded clusters in more distant galaxies with JWST. Guided by the SAGE-LMC catalog, we define JWST color─magnitude selection criteria (F1000W versus F1000W − F2100W) and test them using resolution-degradation experiments. We identify 216, 32, 80, and 139 dusty young objects in the four galaxies, respectively. The selected population spans sources from systems dominated by a single MYSO to compact marginally resolved sources hosting multiple MYSOs. The color selection remains stable across 1─5 Mpc, and the 10 μm luminosity function retains a slope of α ∼ −2. However, blending and surface-brightness dilution remove fainter sources, leading to incompleteness of up to ∼50% at 5.2 Mpc and biasing the sample toward brighter objects (F1000W < 19 mag). The sample spans approximate stellar masses of ∼10─2 × 10⁵ M_⊙. Spatial resolution affects the interpretation of mid-IR emission: clustering increases the fraction of emission attributed to compact sources in active regions, while blending into diffuse emission dominates in quiescent environments. Comparisons with polycyclic aromatic hydrocarbon (PAH)-selected young clusters in the PHANGS galaxy NGC 5068 show that our selection recovers ∼80% of the PAH-selected sources. We show that the practical limit for studying individual MYSOs with JWST is ∼3 Mpc. The resulting catalog provides a foundation for future resolved studies of star formation rates and early cluster evolution.

ALMA-IMF: XXI. N₂H⁺ kinematics in the G012.80 protocluster: Evidence of filament rotation and evolution

First Author: Salinas, J.
Instruments: ALMA_Band_6
ProgramIDs: 2017.1.01355.L
BibCode: 2026A&A...711A.239S

We characterize kinematic processes in the G012.80 protocluster. We primarily focused on the N₂H⁺(1−0) emission to trace the dense and cold gas. Additionally, we used complementary lines such as DCN(3-2), H41α, C¹⁸O(2−1), and SiO(5−4), as well as continuum maps. We performed a N₂H⁺ hyperfine spectral line fitting to analyze multiple velocity components and extract spectral parameters. We estimated velocity gradients, column densities, and line-mass profiles for the two main filaments in G012, which we named R1 and R2. The line-mass profiles follow λ(ω) = 5660M_⊙pc⁻¹ (ω/pc)^0.30 for R1 and λ(ω) = 6943 M_⊙pc⁻¹(ω/pc)^0.20 for R2. This is much larger than profiles of typical low-mass filaments. R1 and R2 show disparate position-velocity (PV) features. R1 exhibits a transverse velocity gradient of 10.4 km s⁻¹ pc⁻¹ and a few dense cores. This velocity gradient is interpreted with a simple rotation toy model when combined with the line-mass profile, and it corresponds to a rotational timescale of ~0.1 Myr. In contrast, R2 exhibits compact velocity structures (∆V < 2 km s⁻¹), likely due to collapse, as evidenced by the comparatively large number of massive cores and protostellar outflows. R2 is forming prestellar and protostellar cores at a rate of ~ 55.3 M_⊙ Myr⁻¹, with an efficiency similar to the Orion integral shaped filament (ISF). The R1 filament, in contrast, lacks protostellar cores and only contains a few prestellar cores, resulting in an estimated star formation rate of ~4.2M_⊙ Myr⁻¹, which is lower by more than an order of magnitude than that of R2. Combining gas kinematics, core incidence, and the line-mass profiles, we suggest that R1 is younger and still rotates, while R2 has evolved to collapse with a higher star formation rate. G012 thus hosts filaments at different evolutionary stages.

Spatially Resolved Spectral Properties of M87* on Event Horizon Scales

First Author: Zhao, Shan-Shan
Instruments: ALMA_Band_3, ALMA_Band_6
ProgramIDs: 2017.1.00841.V, 2017.1.00842.V
BibCode: 2026ApJ..1006L..24Z

The supermassive black hole at the center of the nearby radio galaxy M87 (M87*) is a prime target for studying black hole physics. Spatially resolved spectral measurements on event-horizon scales can reveal the origin of the emission and probe the plasma and gravitational environment in the immediate vicinity of the black hole. Here, we present an analysis of spectral properties based on nearly simultaneous high-resolution images at 3.5 mm (86 GHz) and 1.3 mm (230 GHz), obtained in 2018 with the Global Millimeter Very Long Baseline Interferometry (VLBI) Array including ALMA and the Greenland Telescope, and the Event Horizon Telescope. We obtain the first spatially resolved spectral-index map (S_ν ∝ ν^α) within the compact region (≤100 μas). We further detect a robust radial gradient with a modest rise in the inner ≲20 μas (slightly inside the 1.3 mm ring), followed by a systematic decline at larger radii. The spectral index transitions from positive to negative values near ∼30 μas, close to the 3.5 mm ring radius, consistent with frequency-dependent synchrotron opacity in the innermost accretion flow. These results provide new observational constraints that can help discriminate between models of the horizon-scale emission and the launching of relativistic jets in M87*.

Isotopic evidence for a cold and distant origin of 3I/ATLAS

First Author: Cordiner, Martin
Instruments: ALMA_Band_7
ProgramIDs: 2025.A.00004.S
BibCode: 2026Natur.655..870C

Interstellar objects provide the only directly observable samples of icy planetesimals formed around other stars, and can therefore provide insight into the diversity of physical and chemical conditions occurring during exoplanet formation^{1, 2─3}. Here we report isotopic measurements of the interstellar comet 3I/ATLAS, which reveal an elemental composition unlike any Solar System body. The water in 3I/ATLAS is enriched in deuterium, at a level of D/H = (0.98 ± 0.06)%, which is more than an order of magnitude higher than in known comets, and its range of ¹²C/¹³C ratios (141─191 for CO₂ and 123─172 for CO) exceeds typical values found in the Solar System, as well as nearby interstellar clouds and protoplanetary disks. Such extreme isotopic signatures indicate formation at temperatures ≲30 K in a relatively metal-poor environment. When interpreted with respect to models for Galactic chemical evolution, the carbon isotopic composition implies that 3I/ATLAS may have accreted as long ago as 12 billion years, following a period of intense, early star formation. 3I/ATLAS thus represents a preserved fragment of an ancient planetary system.

ALMA Central Molecular Zone Exploration Survey (ACES) ─ VI. ALMA large program reveals a highly filamentary Central Molecular Zone

First Author: Battersby, Cara
Instruments: ALMA_Band_3
ProgramIDs: 2021.1.00172.L
BibCode: 2026MNRAS.550g1119B

The Central Molecular Zone (CMZ) of the Milky Way is the way station that primarily controls how much gas flows from the disc of the Galaxy towards the central nucleus. While this region is well documented to have extreme gas properties that clearly distinguish it from the rest of the Galaxy, the properties of the bulk molecular gas at high angular resolution are relatively unexplored. Band 3 data from the ALMA (Atacama Large Millimeter/Submillimeter Array) large program ACES (ALMA CMZ Exploration Survey) reveal the highly filamentary nature of CMZ molecular gas at high resolution (3 arcsec or

$\sim$

0.1 pc) across the entire CMZ. Visual inspection of these data suggests that there are at least two general classes of elongated structures, which we identify as: (i) large-scale (

$\gtrsim 10$

pc) filamentary structures (LFs) and (ii) a ubiquitous population of small-scale (

$\sim 1$

pc) filamentary structures (SFs), both with widths (FWHM) of about 0.1 pc. We present detailed morphological and kinematic properties towards three structures in each category, as well as their association with magnetic fields and the correlation of HNCO 4(0,4)─3(0,3) with other molecular species. Our investigation reveals that these structures are largely coherent in position─position─velocity space. The alignment with the magnetic field structure is mixed, with some parallel, some perpendicular, and some intermediate alignments. We find that LFs likely trace pieces of contiguous CMZ orbital structures and are a manifestation of global CMZ dynamics. The second class, SFs, are pervasive and may be the result of complicated turbulence and shearing dynamics in the CMZ gas flows, as seen in numerical simulations.

Protostellar Outflows at the EarliesT Stages (POETS): IX. Magnetohydrodynamic disk winds traced by SO and SO₂ in luminous protostars

First Author: Moscadelli, L.
Instruments: ALMA_Band_6
ProgramIDs: 2016.1.01036.S
BibCode: 2026A&A...711A.182M

Context. Magnetohydrodynamic (MHD) disk winds (DWs) can be responsible for removing angular momentum from the accretion disks of protostars, for driving mass accretion and disk evolution and dispersal, and, ultimately, for setting the conditions for planet formation. Aims. We want to investigate two massive young stellar objects (YSOs), IRAS 21078+5211 and G035.02+0.35, where evidence for MHD DWs has been previously obtained at scales of 10─100 au through measurements of the 22 GHz water maser velocity distribution within the Protostellar Outflows at the EarliesT Stages survey. The different mass, 5.6±2 M_⊙ and ≍20 M_⊙, of the two YSOs allows us to investigate the dependence of MHD DWs on the YSO environment, too. Methods. We employed IRAM Northern Extended Millimeter Array and archival Atacama Large Millimeter Array observations of IRAS 21078+5211 and G035.02+0.35, respectively, to study the gas kinematics and physical conditions of the corresponding protostellar winds on scales of 100─1000 au using the same molecular tracers. Results. In IRAS 21078+5211, the emissions of several molecules, particularly SO, SO₂, CH₃CN, and CH₃OH, are distributed along the axis of the previously identified radio jet, and present a local standard of rest velocity (V_LSR) gradient transversal to the jet axis. Position-velocity (PV) plots of the SO lines show patterns consistent with Keplerian rotation. The SO₂ emission comes from high-velocity gas flowing close to the jet axis, while CH₃CN and CH₃OH present a larger radial extension than the S-bearing species. In G035.02+0.35, the same molecules are instead distributed along the (sky-projected) major axis of the rotating disk reported previously, and their V_LSR gradients consistently trace the disk rotation. The corresponding PV plots present Keplerian profiles. SO is the only molecular species whose emission extends well outside the disk. Our analysis shows that, in both YSOs, the spatial and velocity distributions of SO are consistent with a rotating wind magneto-centrifugally launched from the YSO disk. The comparison with models of molecule formation and excitation in shocks indicates that the different radial extension of the molecular species observed in the protostellar wind of IRAS 21078+5211, as well as the lack of molecules, except SO, in the G035.02+0.35's wind, can be well explained in terms of a radially extended MHD DW, rather than a compact X-wind. Conclusions. This study provides compelling evidence that the SO and SO₂ emissions can be used to trace MHD DWs in luminous YSOs at scales of 100─1000 au, and confirms the results derived with water masers at scales of 10─100 au.

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