Latest ESO telbib papers

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.

High-resolution ALMA Imaging for a Gravitationally Lensed Quasar at z = 6.5: Constraining the Active Galactic Nucleus Contribution to Galactic-scale Dust Heating

First Author: Yue, Minghao
Instruments: ALMA_Band_6
ProgramIDs: 2018.1.00566.S
BibCode: 2026ApJ..1006L..12Y

We present high-resolution (beam size 0.″076×0.″040 ) Atacama Large Millimeter/submillimeter Array observations of the far-infrared (λ_rest = 162.7 μm) dust continuum of J0439+1634, a gravitationally lensed quasar at z = 6.52. We perform pixelated lens modeling for the visibility data, finding that J0439+1634 is well-described by a singular isothermal ellipsoid plus an external shear lensing model. The best-fit lensing potential exhibits a naked-cusp configuration, confirming the finding in X. Fan et al. The reconstructed source plane continuum emission shows a compact bright core, with size ≲200 pc and peak brightness ∼0.6 Jy arcsec⁻². The total continuum flux at 245 GHz is 3.36 ± 0.02 mJy. The flux magnification is 4.63 ± 0.03, indicating an average source-plane resolution of 0.″019 (equivalent to 104 pc). The spatial resolution around the supermassive black hole reaches ∼36 pc. Leveraging the exceptional source-plane resolution, we build a radiative transfer model to describe the observed dust emission profile. The best-fit model indicates that heated dust from the active galactic nucleus (AGN) dominates the submillimeter emission at r ≲ 100 pc and that star-heated dust dominates the outer region of the host galaxy. AGN heating contributes ∼13% to the observed submillimeter flux. Therefore, previous far-infrared-based star formation rate measurements for most high-redshift quasars are likely mildly overestimated.

The formation radius of HCN in O-rich asymptotic giant branch stars

First Author: Marinho, L.
Instruments: ALMA_Band_7
ProgramIDs: 2019.1.00801.S
BibCode: 2026A&A...711A.159M

Context. Molecules detected in circumstellar envelopes around asymptotic giant branch (AGB) stars are generally well explained in terms of formation under chemical equilibrium in the stellar atmosphere or photochemistry in the outer expanding layers. However, several molecules are detected in the inner circumstellar regions with abundances orders of magnitude above the predictions of chemical equilibrium. Anomalously abundant molecules comprise H₂O, NH₃, SiH₄, and PH₃ in C-rich envelopes and HCN, CS, and NH₃ in O-rich sources. These molecules are formed by some yet unknown nonequilibrium processes. Aims. We aim to shed light on the nonequilibrium process that enhances the abundance of anomalously abundant molecules in the inner regions of circumstellar envelopes. Here, we focus on HCN in O-rich stars to constrain its formation radius. Methods. We observed the O-rich AGB stars R Crt and IK Tau with ALMA at high angular resolution (HPBW = 0.05″) in the J = 4 − 3 line of HCN in both the ground and the ν₂ = 1 vibrational states. The radial distribution of the emission was modeled using a large velocity gradient radiative transfer code in which we considered an abundance profile with a central hole. Results. The models with a hole in the abundance distribution of HCN reproduce the specific shape of the radial emission distribution around the two studied O-rich stars. The best models locate the formation radius of HCN at 4−6 R_★ in R Crt and 3−5 R_★ in IK Tau. Conclusions. The formation radius of HCN inferred from observations is consistent with models that invoke shocked-induced chemistry but also with models where photochemistry acts as the solely disequilibrium process. High angular resolution observations of more O-rich stars and tailored shocked-induced and/or photochemical models are needed to unambiguously unveil the underlying mechanism behind anomalously abundant molecules in AGB envelopes.

Azimuthal brightness modulation reveals hidden rings in CI Tau

First Author: Scardoni, C. E.
Instruments: ALMA_Band_3, ALMA_Band_6, ALMA_Band_7
ProgramIDs: 2015.1.01207.S, 2016.1.01370.S, 2018.1.00900.S, 2017.A.00014.S
BibCode: 2026A&A...711L...8S

Context. Protoplanetary disks often host substructures such as rings and gaps, which trace key processes in planet formation and dust evolution. However, narrow rings may remain unresolved due to limited observational resolution, hiding critical information about early planetesimal formation and the amount of dust present. Aims. We applied the azimuthal brightness modulation method, based on the modulation produced by multiple unresolved optically thick rings embedded in an optically thin background, to multiwavelength ALMA observations of CI Tau to identify unresolved rings and constrain their geometry and optical depth. Methods. We analysed CI Tau archival ALMA continuum observations in bands 3, 6, and 7, and extracted azimuthal brightness profiles along narrow annuli and compared them with forward-modelled synthetic observations of inclined discs containing unresolved rings. Results. We detect the azimuthal signature at ∼22 au in all three bands, consistent with unresolved, optically thick rings embedded in a lower optical depth background. Multiwavelength modelling constrains the rings' geometry and optical depth, consistent with the conditions expected for streaming instability and early planetesimal formation. Conclusions. Our results demonstrate the applicability of this azimuthal signature technique to real discs, reveal fine-scale dust substructures in CI Tau, and illustrate a new method of studying the early stages of planet formation below the nominal resolution limit.

HOTDISK. Finding Massive Protostellar Disks with Water and Refractory Molecular Species

First Author: Yang, Kai
Instruments: ALMA_Band_6
ProgramIDs: 2024.1.01198.S
BibCode: 2026ApJ..1006...25Y

We present high-angular-resolution (∼0 .″ 05, ∼60−250 au) Atacama Large Millimeter/submillimeter Array Band 6 observations from the HOTDISK project (Hot-Origin Tracer survey of DISKs of massive protostars) aimed at investigating the "hot-disk" chemical pattern traced by vibrationally excited water, NaCl, SiS, and SiO in the innermost regions around massive protostars. 10 targets were selected based on strong CH₃CN emission exhibiting clear rotational signatures and centrally concentrated SiO emission from lower-resolution observations. We detect vibrationally excited water emission toward 7 of the 10 sources. In all detections, the blueshifted and redshifted components are compact and located on opposite sides of the 1.3 mm continuum peak, with velocity gradients approximately perpendicular to the outflow axes, consistent with rotation on disk scales. Emission from NaCl and SiS is detected toward five of these seven sources and exhibits similar kinematics, further supporting the presence of compact rotating structures. In contrast, commonly used hot-core tracers (e.g., CH₃CN and SO₂) primarily probe larger-scale envelope gas. These results demonstrate that vibrationally excited water, NaCl, and SiS are powerful tracers of disk structures on ∼100 au scales, when observed at sufficient angular resolution and sensitivity. The high detection rate suggests that hot-disk chemical patterns—and thus compact rotating disks—are common in massive star-forming regions, at least among sources with well-developed rotating envelopes.

Nondetection of HC(S)SH: Estimating Upper Limits and Constraining Chemistry

First Author: Sahu, Dipen
Instruments: ALMA_Band_7
ProgramIDs: 2015.1.00147.S
BibCode: 2026ApJ..1006...30S

The search for dithioformic acid (t─HC(S)SH) in star-forming regions is crucial for understanding interstellar sulfur chemistry and addressing the "missing sulfur" problem. Motivated by a recent claim of t─HC(S)SH detection in NGC 1333 IRAS 4A2, we independently reanalyzed the same Atacama Large Millimeter/submillimeter Array dataset using comprehensive spectral and chemical modeling. We find no credible evidence for t─HC(S)SH: all reported transitions are fully accounted for by known, abundant molecules, with no unblended features unique to t─HC(S)SH. We critically reassess the reported detection, deriving stringent upper limits on the column density (N_t-HC(S)SH ≤ 4 × 10¹⁴ cm⁻²) and the fractional abundance (≤1× 10⁻¹⁰ relative to H₂). Our astrochemical models place these limits in context, showing the claimed detection likely results from spectral blending and inconsistent modeling assumptions. The nondetection aligns with chemical expectations given the rarity of complex and doubly sulfur-substituted molecules in hot corino environments. Furthermore, our analysis establishes a rigorous framework to guide future searches for sulfur-bearing species and highlights the critical importance of thorough line identification and modeling practices in astrochemistry. *Refuting the initial reported detection of HC(S)SH toward IRAS 4A2.

SN 2021aaev: A Hydrogen-rich Superluminous Supernova with Early Flash and Long-lived Circumstellar Interaction in an Unusual Host Environment

First Author: Hu, Yang
Instruments: EFOSC2, XSHOOTER
ProgramIDs: 108.2262, 108.220C, 106.216C
BibCode: 2026ApJ...999..176H

We present photometric and spectroscopic observations of SN 2021aaev, a hydrogen-rich, superluminous supernova with persistent (at least ∼100 days) narrow Balmer lines (SLSN-IIn) at redshift z = 0.1557. SN 2021aaev rose over 28.1 ± 1.0 rest-frame days after explosion, reaching a peak absolute magnitude of −21.46 ± 0.01 in the ATLAS o band. The prepeak spectra resemble those of typical Type IIn SNe with flash-ionization features arising from the interaction with a dense, confined circumstellar medium (CSM), albeit the flash timescale is longer than usual (>20 days). Postpeak, the narrow emission lines evolve slowly, and the absence of ejecta features indicates strong deceleration by the CSM. The total radiated energy (about 1.41 × 10⁵¹ erg) is possibly explained by a low-mass (1─2 M_⊙) ejecta ploughing into a massive (9─19 M_⊙), extended (outer radius >1 × 10¹⁶ cm) H-rich CSM, or alternatively by magnetar-powered models. Interestingly, the host environment consists of a spiral galaxy with a red substructure in the southeastern part, and the SN's exact location coincides with this quiescent red region (star formation rate =0.02−0.02+0.13M⊙ yr⁻¹). Given the atypical environment and the obscuring effect of the massive CSM, a thermonuclear (Type Ia-CSM) origin cannot be ruled out. Altogether, SN 2021aaev is a compelling case to study the diversity of SLSN-IIn features and their host environments.

ASPIRE: The Environments and Dark Matter Halos of Luminous Quasars in the Epoch of Reionization

First Author: Wang, Feige
Instruments: ALMA_Band_6
ProgramIDs: 2022.1.01077.L
BibCode: 2026ApJ..1006...39W

We present a systematic study of the environments of 25 luminous quasars at z > 6.5 from the ASPIRE program. Using JWST/NIRCam wide-field slitless spectroscopy data, we identified 487 galaxies at 5.3 ≲ z ≲ 7.0 exhibiting [O III] emission. Among these, 122 [O III] emitters lie within ∣∆v_los∣ < 1000 km s⁻¹ of the quasars, corresponding to a ∼9.4-fold enhancement relative to the average galaxy density at other redshifts. Furthermore, we identified 16 [C II]-emitting galaxies at the quasar redshifts from Atacama Large Millimeter/submillimeter Array (ALMA) mosaic observations. A cross-correlation function analysis between quasars and [O III]+[C II] emitters yields a cross-correlation length of r0QG=8.68−0.55+0.51h−1cMpc and an autocorrelation of r0QQ=15.76−2.70+2.48h−1cMpc , indicating that z ∼ 7 quasars reside in dark matter halos with Mhalo=1012.27−0.26+0.21M⊙ and have a quasar lifetime of tQ=107.05−1.01+0.95yr . Notably, the number of [O III]-emitting galaxies at quasar redshifts varies significantly from field to field, ranging from 0 to 20, highlighting a diverse quasar environment. Remarkably, seven quasars trace significant galaxy overdensities (i.e., protoclusters), with δ_gal > 5 within a volume of V ∼ 500 cMpc³. We also find that ∣∆v_los∣ increases rapidly toward smaller galaxy─quasar separations in protocluster fields, consistent with galaxy kinematics around extremely massive halos in cosmological simulations. By combining JWST and ALMA data, we reveal the complex and diverse environments of these early quasars, providing robust evidence that the earliest luminous quasars are effective tracers of galaxy overdensities, albeit with substantial field-to-field variation.

GOTO identification and broad-band modelling of the counterpart to the SVOM GRB 250818B

First Author: Belkin, S.
Instruments: ALMA_Band_3
ProgramIDs: 2024.1.01131.T
BibCode: 2026MNRAS.550g1193B

We present the discovery and multiwavelength follow-up of gamma-ray bursts (GRB) 250818B, detected by the Space Variable Objects Monitor (SVOM) and localized by the Gravitational-wave Optical Transient Observer. We compile X-ray, optical/near-infrared, and radio data into broad-band light curves and spectral energy distributions. Despite being initially reported as short, the public prompt light-curve figure suggests a duration of

$\sim 5$

s, arguing against a secure short-duration classification. The afterglow is unusually bright relative to short-GRB samples: in X-rays and optical it is broadly consistent with the long-GRB population, while in the radio it is among the most luminous events in the short-GRB comparison sample and remains within the long-GRB range. MeerKAT detects the source at 3.1 GHz, while the Atacama Large Millimetre/submillimetre Array provides deep higher-frequency limits. Keck/LRIS spectroscopy shows continuum and metal absorption (Fe II, Mg II, Mg I), giving

$z=1.216$

. Synchrotron forward-shock modelling favours a constant-density medium and refreshed (energy-injection) emission, well described by a two-component jet with core isotropic-equivalent kinetic energy

$E_{0}\sim 8\times 10^{52}$

erg, ambient number density

$n_0\sim 12\, \mathrm{cm^{-3}}$

, jet half-opening angle

$\theta _j\simeq 0.13$

rad (

$\sim 7.4^\circ$

), and electron index

$p\simeq 1.67$

. We do not identify a host conclusively: the data admit either a faint LS DR10 galaxy at

$\sim 4\, {\rm arcsec}$

(

$\sim 34$

kpc) as an offset candidate, or a fainter, near-coincident uncatalogued host. GRB 250818B highlights the power of rapid counterpart identification in the SVOM era, while uncertain prompt classification and inconclusive host association still limit progenitor interpretation.

From chemical space to observational priority: Predicting detectable molecules in IRC+10216

First Author: Li, Guangping
Instruments: ALMA_Band_3, ALMA_Band_6
ProgramIDs: 2013.1.00432.S, 2019.1.00592.S
BibCode: 2026A&A...707A..72L

Context. IRC+10216 is a carbon-rich asymptotic giant branch star surrounded by a dense, chemically rich circumstellar envelope (CSE). Although a diverse array of molecules has been detected, the full molecular inventory of the envelope and the formation pathways of more complex species remain poorly understood. Aims. This study aims to systematically identify plausible new molecular candidates in the CSE of IRC+10216, predict their column densities, and prioritize the most promising targets for observational detection using a combined cheminformatics and machine learning approach. Methods. We conducted a structural similarity search based on known molecular species using extended connectivity fingerprints, retrieving 1133 plausible candidates from chemical databases. A support vector regression model was trained to predict their column densities. The resulting candidates were filtered using criteria based on elemental abundance, kinetic plausibility, and spectral line intensities to identify observationally feasible targets. Results. The filtering process reduced the candidate list to 30 high-priority molecules with entries in spectroscopic catalogs. Density functional theory calculations provided key molecular properties for these species, including optimized geometries, formation energies, dipole moments, zero-point vibrational energies, and rotational constants. Conclusions. The integrated framework developed here enables efficient identification and prioritization of plausible molecular candidates in IRC+10216.

The converging gas flow around the infrared dark cloud G28.37

First Author: Beuther, H.
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: 2026A&A...706A.329B

Context. How dense clouds and star-forming regions form out of the dynamical interstellar medium is at the heart of star formation research. Aims. The G28.37+0.07 star-forming region is a prototypical infrared dark cloud (IRDC) located at the interface of a converging gas flow. This study characterizes the properties of this dynamic gas flow. Methods. Combining data from the Northern Extended Millimeter Array (NOEMA) with single-dish data from the IRAM 30 m observatory, we mapped large spatial scales (~81 pc²) at high angular resolution (7.0″ × 2.6″ corresponding ~2.3×10⁴ au or ~0.1 pc) down to core scales. The spectral setup in the 3 mm band covers many spectral lines as well as the continuum emission. Results. The data clearly reveal the proposed west─east converging gas flow in all observed dense gas tracers. We estimate a mass-flow rate along that flow around 10⁻³ M_⊙ yr⁻¹. Comparing these west─east flow rates to infall rates toward sources along the line of sight, the gas flow rates are roughly a factor of 25 greater than those along the line of sight (roughly perpendicular to the west─east flow). This confirms the dominance of longitudinal motions along the converging gas flow in this region. For comparison, in the main north─south IRDC formed by the west─east converging gas flow, infall rates along the line of sight are about an order of magnitude greater than those along the west─east flow. In addition to the kinematic analysis, a comparison of CH₃ CN-derived gas temperatures with Herschel- derived dust temperatures typically show higher gas temperatures toward high-density sources. We discuss whether mechanical heating from the conversion of the flow's kinetic energy into thermal energy may explain some of the observed temperature differences. Conclusions. Our analysis of the G28.37+0.07 converging gas flow shows that such structures can indeed form and feed typical highmass star-forming regions in the Milky Way. The differences between flow rates along the converging flow, perpendicular to it, and toward the sources at the IRDC center indicate that at the interfaces of converging gas flows ─ where most of the active star formation takes place ─ originally more directed gas flows can convert into multidirectional infall motions.

EIGER. VIII. First Stars Signatures in the Connection between O I Absorption and Galaxies in the Epoch of Reionization

First Author: Higginson, Jack
Instruments: XSHOOTER
ProgramIDs: 096.A-0095
BibCode: 2026ApJ...999...49H

We investigate the association between galaxies and neutral O I absorption systems at z ∼ 6, which trace metal-enriched gas during the epoch of reionization. We identify 40 galaxies across six quasar fields, residing in 15 overdensities within 300 kpc of the background sight lines. Five O I absorption systems are associated with five of these overdensities, yielding a covering fraction of 0.27−0.10+0.13 within 300 kpc. The absorption occurs beyond typical virial radii, indicating that the gas traces extended overdensity environments rather than individual galaxy halos, unlike the z ∼ 0 circumgalactic medium (CGM), which is largely bound to halos. These galaxy-associated absorbers account for ∼35% of all O I systems seen in blind quasar surveys, implying the remainder arise in lower-mass galaxies below our detection threshold or in dense neutral intergalactic medium pockets. The CGM around these galaxies contains ≳ 2 × 10⁶ M_⊙ of oxygen, comparable to the interstellar medium oxygen mass of the galaxies themselves, suggesting that the surrounding environment holds as much metal mass as the galaxies. All five galaxy-associated systems show significantly higher log(NCII/NOI) ratios than absorbers lacking galaxy associations. Furthermore, relative abundance ratios ([Si/O], [C/O]) reveal that four of the five exhibit enrichment patterns consistent with Population III nucleosynthesis at the outskirts of galaxy overdensities. These rare systems offer a unique window into the role of first-generation stars in shaping the early metal enrichment of galaxies and their environments.

Chasing the Tides: Searching for Orbital Decay Signatures in Transit Timing Data and Tidal Models for 20 Hot Jupiters

First Author: Kutluay, Ahmet Cem
Instruments: EFOSC2, GROND
ProgramIDs: 084.D-0056, 088.C-0204
BibCode: 2026PASP..138b4405K

In this work, we present a transit timing variation analysis for 20 hot Jupiter systems, which we interpret with theoretical tidal dissipation models. For the majority of the sample, we conclude that a constant orbital period model represents the timing data best. Only WASP-12 b, TrES-1 b and WASP-121 b exhibit a changing orbital period, according to the most up-to-date results. We updated the orbital decay rate of WASP-12 b to Ṗ=−29.4±4.0msyr−1 and the corresponding stellar tidal quality factor to Q∗'=1.72±0.18×105 . For TrES-1 b, the median quadratic model suggests a period decrease at a rate of −14.9 ± 0.6 ms yr⁻¹, but the corresponding Q∗'=570±60 does not agree with the theoretical estimates, which suggest Q∗'∼106 due to internal gravity wave dissipation. Lastly, WASP-121 b exhibits orbital growth at a rate of 15.1 ± 0.8 ms yr⁻¹, and theoretical results support outward migration due to strong inertial wave dissipation.

Reconstructing the Assembly of Massive Galaxies. III. Quiescent Galaxies Lose Angular Momentum as They Evolve in a Mass-dependent Fashion

First Author: Ji, Zhiyuan
Instruments: VIMOS
ProgramIDs: 194.A-2005, 1100.A-0949
BibCode: 2026ApJ...999...20J

We study the evolution of stellar kinematics of a sample of 952 massive quiescent galaxies with M_* > 10^10.5 M_⊙ at 0.6 < z < 1. Utilizing spatially integrated spectroscopy from the LEGA-C survey, we focus on the relationship between the observed integrated stellar velocity dispersion ( σstar' ) and the morphological axial ratio (q), and its variation with the stellar age and mass of quiescent galaxies. For the youngest quiescent galaxies, regardless of stellar mass, σstar' decreases with increasing q, a trend that is consistent with a system having significant rotation and hence suggests that massive galaxies still retain a significant amount of angular momentum in the aftermath of quenching. As they continue to evolve, the variation of the σstar' -q relationship depends on stellar mass. For quiescent galaxies with M_* < 10^11.3M_⊙, σstar' decreases with q in all stellar-age bins, suggesting that the quiescent populations of this mass regime retain significant rotation even a long time after quenching. In contrast, for more massive quiescent galaxies with M_* > 10^11.3M_⊙, the relationship between σstar' and q becomes significantly flattened with increasing stellar age. This indicates that, as the very massive galaxy populations continue to evolve after quenching, angular momentum gradually reduces, which eventually transforms them into velocity-dispersion supported systems. We suggest that incoherent, continuous merging and accretion events onto the galaxies are the main drivers of the observed mass-dependent, postquenching dynamical evolution because more massive galaxies are more likely to undergo such interactions. We are witnessing the early formation epoch of fast and slow rotators at z ∼ 0.8, when the Universe was only half of its current age.

Wide binaries without viable bound Newtonian orbits

First Author: Pasquini, L.
Instruments: ESPRESSO
ProgramIDs: 106.21H3, 108.22FH, 109.23FD
BibCode: 2026A&A...707L...2P

Context. Wide binaries offer a unique opportunity to test gravity in the low-acceleration regime, where deviations from Newtonian dynamics may appear. Aims. We used high-resolution VLT─ESPRESSO archival spectra to study 26 wide binaries with projected separations > 13 000 AU. By combining precise radial velocities with Gaia proper motions and parallaxes, we tested whether these systems are consistent with Newtonian gravity in the low-acceleration regime. Methods. We used multiple radial-velocity measurements and stellar parameters to remove systems affected by unresolved triple or chance alignments as well as young systems. For the remaining binaries, we combined radial velocities (corrected for convective shift and gravitational redshift) with Gaia proper motions, parallaxes, and positions in a bid to find bound Newtonian orbital solutions. Results. Of the 26 initial systems, 14 were discarded: 12 due to radial-velocity variability indicating unresolved close binaries, 1 that hosts a faint Gaia companion, and 1 that is too young. Of the remaining 12, 9 can be fitted with a bound orbital solution, while the velocity differences of the other 3 are too large to be reconciled with any bound Newtonian orbit. Conclusions. For the three systems that cannot be fitted with a bound orbit, repeated radial-velocity observations allowed us to confidently exclude, with one possible exception, unresolved triple stellar companions or massive close-in planets as causes. Given their likely large 3D separations, these binaries may have been dynamically perturbed or disrupted by stellar encounters or Galactic tides, and may no longer be gravitationally bound. This highlights how utmost caution must be applied when studying wide binaries as isolated systems.

Enhanced detection limits in the SHINE F150 survey through the regime switching model: Optimizing thresholds and investigating environmental noise

First Author: Sabalbal, M.
Instruments: SPHERE
ProgramIDs: 198.C-0209, 1100.C-0481, 1104.C-0416, 110.240D, 111.24QL, 113.2689
BibCode: 2026A&A...706A.275S

Context. In high-contrast imaging, a novel detection algorithm for angular differential imaging (ADI) sequences has recently been introduced: the regime switching model (RSM). This advanced statistical tool enhances the distinction between planetary signals and bright speckles by simultaneously combining multiple ADI-based post-processing techniques. Aims. In this study, we apply the RSM algorithm to analyze the F150 sample from the SHINE high-contrast imaging survey carried out with VLT/SPHERE, aiming to enhance detection limits and identify new exoplanet candidates. Additionally, we investigate how environmental conditions influence post-processed noise distributions and detection thresholds. Methods. We generated detection maps and contrast curves for 213 observations in the F150 SHINE sample using the RSM algorithm. A clustering approach based on environmental parameters was used to group observations with similar noise characteristics. We propose two methods for defining radial detection thresholds in the RSM maps: fitting a lognormal distribution to the post-processed noise and maximizing the F1 score. We also assessed the performance of various combinations of post-processing techniques within the RSM framework to identify optimal configurations. Results. This study demonstrates the utility of clustering based on observational parameters, effectively distinguishing features such as wind-driven halos and low-wind effects. Detection thresholds vary significantly across clusters, differing by up to a factor of ten, highlighting the importance of considering observational environments. Lognormal thresholds provide conservative, noise-aware limits, while F1 score-based thresholds offer observation-specific results, with both showing compatibility overall. RSM improves detection limits by an average factor of two at 1" and five at inner working angles compared to standard principal component analysis processing. This study reports more than 30 newly detected signals, including one promising candidate awaiting second-epoch confirmation.

GATOS ─ XI. Excess dust heating in the narrow-line regions of nearby AGN revealed with JWST/MIRI

First Author: Haidar, Houda
Instruments: SINFONI
ProgramIDs: 086.B-0484, 086.B-0635, 076.B-0845, 093.B-0458, 075.A-0250, 094.B-0357, 078.B-0289, 092.B-0520, 088.B-0206, 0101.B-0331, 091.B-0129, 094.B-0009, 60.A-9235, 077.B-0151, 084.B-0894, 078.B-0505, 080.B-0336, 083.B-0126, 086.B-0781, 082.B-0611, 078.B-0103, 076.B-0098, 089.B-0971, 083.B-0620, 084.B-0086, 083.B-0332, 084.B-0568, 60.A-9041, 082.B-0709, 093.B-0734, 093.B-0057, 098.B-0028
BibCode: 2026MNRAS.546ag069H

We present James Webb Space Telescope/Mid-Infrared Instrument imaging of eight nearby active galactic nuclei (AGN) from the GATOS (Galactic Activity, Torus, and Outflow Survey) survey to investigate the physical conditions of extended dust in their narrow-line regions (NLRs). In four galaxies (ESO 428─G14, NGC 4388, NGC 3081, and NGC 5728), we detect spatially resolved dust structures extending

${\sim}$

100─200 pc along the NLR. In these systems, we find a strong link between the morphology of the dust, the radio ejecta, and the coronal [Si VI] emission, implying that dust carries imprints of the processes shaping the NLR. Using spatially resolved spectral energy distributions, we show that dust in the NLR has systematically steeper slopes than star-forming clumps. This dust emits at temperatures in the range

$150 \text{-} 220\, \rm K$

, at a distance of

$\sim$

150 pc from the nucleus. Using simple models, we show that, even under optimistic assumptions of grain size and AGN luminosity, the excess mid-infrared emission cannot be explained by AGN illumination alone. We interpret this excess heating as in situ. We show that shocks with velocities

$v_{\rm shock} \sim 200 \text{-} 400 \, \rm km \, s^{-1}$

in dense gas can close this gap, and in some cases even account for the total observed emission. This, combined with multiple lines of evidence for shocks in these regions, supports a scenario in which shocks not only coexist with dust but may be playing a key role in heating it. Our findings reveal shocks may be an important and previously overlooked driver of extended dust emission in the central hundreds of parsecs in AGN.

Gaia20dsk: A new MNor discovered by the GLORIOUS collaboration

First Author: Németh, Patrik E.
Instruments: XSHOOTER
ProgramIDs: 109.23F6
BibCode: 2026A&A...706A.332N

Context. Among known young stellar objects (YSOs), those exhibiting the most dramatic increases in brightness due to sudden increase in mass accretion rate are eruptive young stars. Gaia20dsk is one of the Gaia-alerted young star candidates that has displayed a double, nonperiodic brightening resembling that of other young eruptive stars. Aims. The goal of this work is to determine the physical and accretion properties of Gaia20dsk to confirm its classification as an eruptive young star. Methods. We combined publicly available optical and near-infrared (NIR) photometry with our X-shooter optical/NIR spectrum. In our analysis, we examined the optical and IR light curves from the bursts, reviewing the color-magnitude diagrams across different bands, reporting the detection of emission lines, and providing estimates of the star's accretion rates during the burst. Results. The optical light curve shows two major and one brief brightening events with an maximum amplitude of ∼ 1.8 mag in the last five years. A classification based on spectral index indicates that Gaia20dsk is a flat-spectrum star. The X-shooter spectrum exhibit emission lines characteristic of accreting low-to-intermediate-mass young stars, displaying features typical of MNor-type objects. The mass accretion rate is between (0.5−1.8) × 10⁻⁶ M_⊙/yr. Conclusions. Gaia20dsk is an eruptive YSO that exhibits photometric features similar to those of MNors, including its characteristic brightening amplitude and burst duration, along with similar spectroscopic features and accretion rates.

2MASS Reprocessing. I. The Search for Faint Objects

First Author: Liu, Zehao
Instruments: VIRCAM
ProgramIDs: 179.A-2010
BibCode: 2026AJ....171..190L

We present an automated, DAOFind-based pipeline developed to reprocess J-band Atlas All Sky Release Survey images from the Two Micron All Sky Survey (2MASS). By optimizing the detection parameters and implementing a screening procedure that jointly evaluates the signal-to-noise ratio and central sharpness, the pipeline effectively identifies faint point sources that were previously undetected. Applying this method to eight representative sky regions improves the 2MASS detection limit from 16.20 to 16.60 mag and increases the number of detected point sources by approximately 21.36% relative to the 2MASS Point Source Catalog, with a false-positive rate of only 4.80%. These results demonstrate that the proposed reprocessing pipeline can substantially enhance the scientific yield of archival 2MASS data, providing valuable faint-source supplements for studies of time─domain variability, Galactic structure, and cold, low-luminosity objects.

VLT/SPHERE images of the candidate companion of Betelgeuse

First Author: Montargès, M.
Instruments: SPHERE
ProgramIDs: 114.28H9
BibCode: 2026A&A...711L..12M

Context. Although the binary fraction of massive main-sequence stars is well established, this is much less so the case for red supergiant (RSG) stars due to the primary's brightness as well as its complex and strong surface activity. Aims. Betelgeuse is the most studied RSG. In 2024, through a reinterpretation of its long secondary period (LSP), a close orbiting stellar companion was suggested to exist, with a maximum elongation in December 2024. Our goal with this work was to search for this secondary component. Methods. We used extreme adaptive optics direct imaging with the Very Large Telescope SPHERE-ZIMPOL instrument by leveraging the pupil tracking mode of the telescope in angular plus spectral differential imaging (ASDI). Image processing was performed through ASDI PAtch Covariances (PACO ASDI) and principal component analysis (PCA). Results. The candidate Betelgeuse B was detected at 6.1σ with PACO ASDI and at 5.1σ with PCA in the CntHa filter on December 6, 2024. The separation is 52.32 ± 0.18 mas, and the position angle is 117.12 ± 0.60°. Assuming the two stars are coeval, the companion is a 2.6 to 3.1 M_⊙ young main-sequence star. Conclusions. Our observations provide strong evidence that Betelgeuse has a close companion, though formal confirmation that Betelgeuse B is indeed gravitationally bound awaits a second observing epoch. The predicted existence of a companion based on LSP variability and the evidence of the presence of the secondary source reported here identifies LSPs as a potential new avenue for RSG-companion studies, and assessments of their impact on RSG surface and wind structure.

GA-NIFS: interstellar medium properties and tidal interactions in the evolved massive merging system B14-65666 at z = 7.152

First Author: Jones, Gareth C.
Instruments: ALMA_Band_3, ALMA_Band_6, ALMA_Band_7, ALMA_Band_8
ProgramIDs: 2015.1.00540.S, 2016.1.00954.S, 2017.1.00190.S, 2018.1.01673.S, 2019.1.01491.S
BibCode: 2026MNRAS.547ag336J

We present JWST/NIRSpec IFU observations of the

$z=7.152$

galaxy system B14-65666, as part of the GA-NIFS survey. Line and continuum emission in this massive system (

$\log _{10}(M_*/{\rm M}_{\odot })=9.8\pm 0.2$

) is resolved into two strong cores surrounded by diffuse emission, as seen in recent JWST/NIRCam imaging. Our data set contains detections of [O II]

$\lambda \lambda 3726{,}3729$

, [Ne III]

$\lambda \lambda 3869{,}3968$

, Balmer lines, [O III]

$\lambda \lambda 4959{,}5007$

, He I

$\lambda 5875$

, and weak [O III]

$\lambda 4363$

. Each spectrum is fit with a model that consistently incorporates interstellar medium conditions (i.e. electron temperature,

$T_{\rm e}$

, electron density,

$n_{\rm e}$

, and colour excess,

$E(B-V)$

). The resulting line fluxes are used to constrain the gas-phase metallicity (

$Z_{\rm g}\sim 0.2\mathrm{ -}0.3$

solar) and H

$\beta$

-based star formation rate for each region. Common line ratio diagrams (O32─R23, R3─R2, Ne3O2─R23) reveal that each line-emitting region lies at the intersection of low- and high-redshift galaxies, suggesting low ionization and higher metallicity compared to the predominantly lower-mass galaxies studied with the JWST/NIRSpec IFU so far at

$z\gt 5.5$

. Spaxel-by-spaxel fits reveal evidence for both narrow (FWHM

$\lt 400$

km s

$^{-1}$

) and broad (FWHM

$\gt 500$

km s

$^{-1}$

) line emission, the latter of which likely represents tidal interaction or outflows. Comparison to ALMA [C II]158

$\mu$

m and [O III]88

$\mu$

m data shows a similar velocity structure, and we explore optical-far infrared diagnostics. The two core galaxies both lie on the mass-metallicity relation at

$z\gt 4$

, but show contrasting properties (e.g.

$M_*$

$Z_{\rm g}$

), suggesting distinct evolutionary pathways. Combining the NIRSpec IFU and ALMA data sets, our analysis opens new windows into the merging system B14-65666.

Exploring the interplay between molecular and ionized gas in H II regions

First Author: Khan, S.
Instruments: SEPIA, nFLASH
ProgramIDs: unknownID
BibCode: 2026A&A...706A.280K

Context. Massive stars strongly impact their natal environments and influence subsequent star formation through feedback mechanisms such as shocks, outflows, and radiation. H II regions are key laboratories for studying this impact. To understand such feedback, it is crucial to characterize the physical conditions of the dense molecular gas in which these regions are embedded. Aims. We aim to constrain the kinetic temperature and H₂ volume density of massive star-forming clumps associated with H II regions using multiple p─H₂CO transitions. In addition, we investigate the interplay between ionized gas, molecular gas, and dust to probe how massive stars influence their parental clumps. Methods. We observed the J_{K_aK_c} transitions of p─H₂CO (within its J = 3─2 and 4─3 states) with the Atacama Pathfinder EXperiment (APEX) 12 m submillimeter telescope, using the nFLASH230 and SEPIA345 receivers toward a sample of 61 H II regions. We derived spectral line parameters via multicomponent Gaussian fitting, which was then used to constrain the physical conditions determined using PyRADEX, a non─local thermodynamic equilibrium (LTE) radiative transfer code in combination with Markov chain Monte Carlo analysis. Results. The non-LTE analysis yielded kinetic temperatures (T_kin) ranging from 33.7 K to 265 K and H₂ densities (n(H₂)) between 0.8 × 10⁴ and 1.05 × 10⁷ cm⁻³, providing a detailed characterization of the dense molecular gas contained in these clumps. In addition to the p─H₂CO emission arising from the targeted clump, a large fraction (57%) of the sources exhibited multiple p─H₂CO components, with the secondary components being characterized by a higher T_kin and broader line widths. Investigation of the nature of the secondary component revealed its association with supersonic nonthermal motions and turbulent gas. When comparing the physical properties of the molecular gas and dust components with those of the ionized gas, we found that parameters directly linked to the central high-mass star, such as bolometric luminosity (L_bol) and Lyman continuum photon rate (N_Lyc), show stronger and more systematic correlations. These findings emphasize the role of the central star in governing the interplay between the molecular and ionized gas. In our sample of H II regions, the pressure of the neutral gas systematically exceeds that of the ionized gas. This suggests that the surrounding neutral molecular medium can hinder or slow down the expansion of H II regions due to its higher pressure. However, given the limited spatial resolution, a definitive conclusion on the role of molecular gas in confining H II regions cannot be made until high resolution observations are obtained.

Evolution of the infrared luminosity function and its corresponding dust-obscured star formation rate density out to z ∼ 6

First Author: Koprowski, M. P.
Instruments: ALMA_Band_7
ProgramIDs: 2017.1.01492.S, 2016.1.00434.S, 2015.1.01528.S, 2012.1.00090.S
BibCode: 2026A&A...706A.345K

We present a new determination of the evolving far-infrared (FIR) galaxy luminosity function (LF) and the resulting inferred evolution of dust-obscured star-formation rate density (ρ_SFR) out to redshift z ∼ 6. To establish the evolving comoving number density of FIR-bright objects, we made use of AS2UDS, a high-resolution ALMA follow-up study of the JCMT SCUBA-2 Cosmology Legacy Survey (S2CLS) submilliter imaging in the UKIDSS UDS survey field. In order to estimate the contributions of faint and low-mass sources, we implemented a method in which the faint-end of the IR LF is inferred by stacking (in stellar mass and redshift bins) the optical and near-infrared samples of star-forming galaxies into the appropriate FIR Herschel and submillimeter JCMT maps. Using this information we determined the faint-end slope of the FIR LF in two intermediate redshift bins (where it can be robustly established) and then adopted this result at all other redshifts. The evolution of the characteristic luminosity of the galaxy FIR LF, L_★, is found to increase monotonically with redshift, evolving as L_★ ∝ z^{1.38 ± 0.07}, while the characteristic number density, Φ_★, is well fit by a double power-law function; it is constant at z < 2.24 and declines as z^{−4.95 ± 0.73} at higher redshifts. We then calculated the evolution of the corresponding dust-obscured star-formation rate density and compared it with the results from a number of recent studies in the literature. Our analysis confirms that dust-obscured star formation activity dominates ρ_SFR at cosmic noon but then becomes progressively less important with increasing redshift. While dusty star-forming galaxies are still found out to the highest redshifts explored here, UV-visible star formation dominates at z > 4, and dust-obscured activity contributes less than 25% to the star formation rate density by z ∼ 6.

LRPayne: Stellar parameters and abundances from low-resolution spectra

First Author: Vernekar, Nagaraj
Instruments: HARPS
ProgramIDs: 082.B-0610
BibCode: 2026A&A...706A.217V

Aims. This paper introduces LRPayne, a novel algorithm designed for the efficient determination of stellar parameters and chemical abundances from low-resolution optical spectra, with a primary focus on data from large-scale galactic surveys such as WEAVE. Methods. LRPayne employs a model-driven approach, utilising a fully connected artificial neural network (ANN), trained on a library of 70 000 synthetic stellar spectra generated using iSpec with 1D model atmospheres and the Turbospectrum synthesis code. We trained the network to predict normalized flux given stellar labels (T_eff, log(g), [Fe/H], v_mic, v_max, and v sin i, plus 24 individual elemental abundances). We subsequently derived stellar parameters from observed spectra by finding the best-fit synthetic spectrum from the ANN using a χ² minimisation technique. The method operates on spectra degraded to a resolution of R=5000 covering the 42006900 Å wavelength range. Results. Internal accuracy tests on synthetic spectra show a median interpolation error of less than 0.13% for 90% of the validation sample. The method accurately recovers most of the input labels from synthetic spectra, even at a signal-to-noise ratio (S/N) of 20, with some expected challenges for elements such as Li, K, and N. Validation on the observed spectra of 25 Gaia FGK benchmark stars and 42 metal-poor stars reveals good agreement with the literature values. For the stellar parameters, the mean differences are 22±87 K for T_eff, 0.19±0.23 dex for log(g), and 0.01±0.17 dex for [Fe/H]. Abundances for elements such as Na, Mg, Si, and most Fe-peak elements (Cr, Ni, V, and Sc) are well-recovered. We note challenges for oxygen, manganese in metal-rich giants, aluminium in metal-poor stars and dwarfs, and deriving log g in hot metal-poor dwarfs, partly due to non-local thermodynamic equilibrium effects and line characteristics. Conclusions. LRPayne demonstrates the possibility of extracting precise stellar parameters and chemical abundances from a large number of low-resolution spectra. Its strong performance across different kinds of stars makes it well-suited for current and future large surveys. The abundance results from LRPayne will be very useful for studying stellar nucleosynthesis and the chemical evolution of our Galaxy on a large scale.

Measuring the intergalactic medium correlation length at 5 < z < 6.1: A fast change at the end of reionization

First Author: Spina, Benedetta
Instruments: XSHOOTER
ProgramIDs: 1103.A-0817
BibCode: 2026A&A...706A.273S

Context. The Lyman-α forest of high-redshift quasars is a powerful probe of the late stages of the epoch of reionization (EoR), in particular thanks to the presence of Gunn-Peterson troughs. These troughs exhibit a broad range of lengths, with some extending up to ∼100 cMpc, suggesting large-scale coherent structures in the intergalactic medium (IGM). Aims. We aim to gain more insight into the presence, extent, and magnitude of correlations in the Lyman-α forest at the end of reionization, at 5 < z < 6.1. In particular, we want to quantify the scales over which correlations are significant in order to help inform the required size of cosmological simulations aiming to capture the evolution of the EoR. Methods. We utilized the extended XQR-30 observational dataset over the redshift range 5 < z < 6.1 (∆z = 0.05) to explore large-scale correlations. After accounting for the relevant systematics, the flux correlation matrix proved to be a powerful tool for probing large-scale correlations across redshifts. We performed a Monte Carlo Markov chain analysis to quantify the extent and strength of the correlation, making use of several functional forms. We moreover employed new large-volume (1.5³ Gpc³) light cones of Lyman-α transmission implementing different reionization scenarios to interpret the observed signal, including a fiducial box employing SCRIPT. Results. We detected strong correlations at redshifts z > 5.3, extending at least tens of megaparsecs and strongly increasing with redshift. Our results suggest a redshift-dependent correlation length, from L ≤ 26.53 (68.47) Mpc at 1σ (2σ) limit at redshift z = 5.0 to L = 252.72^+272.61_−41.61 Mpc L = 252 . 72 − 41.61 + 272.61 Mpc at redshift z = 6.1. On the contrary, our simulations all demonstrate characteristic correlation scales < 60 Mpc with a very slow redshift evolution, in strong tension with our observations. Conclusions. The presence and redshift dependence of correlations in the Lyman-α forest on > 200 Mpc scales at z = 6 indicates that cosmological simulations should be larger than this scale to adequately sample the Lyman-α forest. Despite implementing a fluctuating ultraviolet background and numerous neutral islands at z < 6, and matching well the sightline scatter in the Lyman-α forest, our fiducial SCRIPT-based simulation fails to reproduce the large-scale correlations. It may be that those ingredients are necessary, but insufficient, to understand the unfolding of the EoR.

TDCOSMO: XXIII. Measurement of the Hubble constant from the doubly lensed quasar HE 1104−1805

First Author: Paic, Eric
Instruments: FORS2, MUSE
ProgramIDs: 0102.A-0600, 106.215F, 092.A-0515
BibCode: 2026A&A...706A.270P

Time-delay cosmography leverages strongly lensed quasars to measure the Universe's current expansion rate, H₀, independently from other methods. The latest TDCOSMO milestone measurement primarily used quadruply lensed quasars for their mass profile constraints. However, doubly lensed quasars, being more abundant and offering precise time delays, could expand the sample by a factor of 5, significantly advancing towards a 1% precision measurement of H₀. We present the first TDCOSMO analysis of a doubly imaged source, HE 1104−1805, including the measurement of the four necessary ingredients. First, by combining 17 years of data from the SMARTS, Euler, and WFI telescopes, we measured a time delay of 176.3 ^+11.4_−10.3 − 10.3 + 11.4 days. Second, using MUSE data, we extracted stellar velocity dispersion measurements in three radial bins with 5% to 13% precision. Third, employing F160W HST imaging for lens modelling and marginalising over various modelling choices, we measured the Fermat potential difference between the images. Fourth, using wide-field imaging, we measured the convergence added by objects not included in the lens modelling. By combining these four ingredients, we measured the time delay distance and the angular diameter distance to the deflector, favouring a power-law mass model over a baryonic and dark matter composite model. The measurement was performed blindly to prevent experimenter bias and resulted in a Hubble constant of H₀ = ^+5.8_−5.0 H 0 = 64 . 2 − 5.0 + 5.8 × λ_int km s⁻¹Mpc⁻¹, where λ_int is the internal mass sheet degeneracy parameter. This is in agreement with the TDCOSMO-2025 milestone and its precision for λ_int = 1 is comparable to that obtained with the best-observed quadruply lensed quasars (4─6%). This work is a stepping stone towards a precise measurement of H₀ using a large sample of doubly lensed quasars, supplementing the current sample. The next TDCOSMO milestone paper will include this system in its hierarchical analysis, constraining λ_int and H₀ jointly with multiple lenses.

A JWST Paα Calibration of the Radio Luminosity─Star Formation Rate Relation at z ∼ 1.3

First Author: Seymour, Nick
Instruments: VIRCAM
ProgramIDs: 179.A-2006
BibCode: 2026ApJ...998..306S

As radio emission from normal galaxies is a dust-free tracer of star formation, tracing the star formation history of the Universe is a key goal of the Square Kilometre Array and the Next-Generation Very Large Array. In order to investigate how well radio luminosity traces star formation rate (SFR) in the early Universe, we have examined the radio properties of a JWST Paα sample of galaxies at 1.0 ≲ z ≲ 1.8. In the GOODS-S field, we cross-matched a sample of 506 FRESCO Paα emitters with the 1.23 GHz radio continuum data from the MeerKAT MIGHTEE survey, finding 47 detections. After filtering for active galactic nuclei (via X-ray detections, hot mid-infrared dust, and extended radio emission), as well as blended sources, we obtained a sample of star-forming galaxies comprising 11 cataloged radio detections, 18 noncataloged detections (at ≍3σ─5σ), and 298 undetected sources. Stacking the 298 undetected sources, we obtain a 3.3σ detection in the radio. This sample, along with a local sample of Paα emitters, lies along previous radio luminosity/SFR relations from local (<0.2) to high redshift (z ∼ 1). Fitting the FRESCO data at 1.0 ≲ z ≲ 1.8, we find log(L1.4GHz)= (1.31 ± 0.17) × log(SFRPaα)+ (21.36 ± 0.17), which is consistent with other literature relations. We can explain some of the observed scatter in the L_1.4GHz/SFR_Paα correlation by a toy model in which the synchrotron emission is a delayed/averaged tracer of the instantaneous Paα SFR by ∼10/75 Myr.

A Comprehensive Analysis of the Panchromatic Transmission Spectrum of the Hot-Saturn WASP-96 b: Nondetection of Haze, Possible Sodium Limb Asymmetry, Stellar Characterization, and Formation History

First Author: Wang, Le-Chris
Instruments: FORS2
ProgramIDs: 199.C-0467
BibCode: 2026AJ....171..147W

We conduct a reanalysis of the JWST NIRISS/SOSS observation of the hot-Saturn WASP-96 b. Initial analysis of this data revealed an enhanced Rayleigh scattering slope at the blue end of the transmission spectrum, suggesting the presence of hazes at high altitudes. In this work, we report nondetection of this slope, confirming an atmosphere clear of high-altitude aerosols consistent with the pre-JWST results. Also contrary to the initial result, our results indicate the presence of gray cloud deck, although at relatively low altitudes/high pressures. We further combined the NIRISS/SOSS spectrum with the Very Large Telescope, Hubble Space Telescope, and Spitzer to produce a transmission spectrum from 0.35─5 μm. We constrain the mass fraction of multiple chemical species, including: H₂O =−2.62−0.42+0.43 , K =−5.76−1.13+1.05 , and Na =−3.40−0.92+0.90 . C/O ratio and metallicity are tentatively constrained at substellar values ( C/Oplanet=0.57−0.12+0.07 and [Fe/H]planet=0.01−0.52+0.46 compared to C/O_star = 0.92 ± 0.25 and [Fe/H]_star = 0.24 ± 0.05). Inputting these composition constraints to interior structure models, we constrain a core mass of 43−15+8 M_⊕. This, in addition to our inferred super-stellar refractory-to-oxygen ratio ( ∆log10(R/O)=1.48−0.62+0.57 ) and substellar C/O ratio, suggests that the core of WASP-96 b likely formed outside of the water ice line, underwent disk-driven migration, and accreted its atmosphere inside the carbon soot line. We find evidence of atmospheric leading-trailing terminator asymmetries in the broadened sodium absorption feature with a transit time offset of 50 s, while the water features appear symmetric. CH₄, CO, and CO₂ remain unconstrained due to spectral coverage limits. Upcoming JWST NIRSpec/G395H observations (ID 4082, PI: M. Radica) will be crucial for constraining these carbon-bearing species.

Infrared photometry and calcium triplet spectroscopy of the most metal-poor in situ globular cluster VVV-CL001

First Author: Moya, W. Haro
Instruments: FORS2, VIRCAM
ProgramIDs: 091.D-0389, 089.D-0392, 179.B-2002
BibCode: 2026A&A...706A.114M

Context. The characterization of globular clusters (GCs) in the Galactic bulge is a challenging task due to high extinction and severe stellar crowding. VVV-CL001 is a poorly studied GC located in the inner bulge, known for its extremely old age, extreme velocity, and low metallicity. Given its unique properties, a detailed study of this cluster can provide valuable insights into the early chemical and dynamical evolution of the Milky Way (MW). Aims. The aim of this study was to derive the fundamental parameters of VVV-CL001 including metallicity, heliocentric radial velocity (RV), proper motions (PMs), structural properties, orbit, and age, in order to improve our understanding of its origin and role in the early evolution of the MW. Methods. We combined spectroscopic, astrometric, and photometric data to characterize VVV-CL001. Metallicity and RV were determined from medium-resolution spectra obtained with FORS2 at the Very Large Telescope. PMs were derived using Gaia DR3 data. Near-infrared photometry from the FourStar instrument on Magellan was used to refine the cluster's position, construct a radial density profile, and estimate its age, distance, and reddening. Results. Our results confirm that VVV-CL001 is an old 12.1_−1.2^+1.0 Gyr), metal-poor ([Fe/H] = −2.25 ± 0.05 dex) globular cluster located at a heliocentric position of d_⊙ = 7.1_−1.1^+1.3, with a reddening of E(J − K_s) = 1.40_−0.02^+0.01. Its mean PMs are μ_α^* = −3.68 ± 0.09 mas yr⁻¹ and µ_δ = −1.76 ± 0.10 mas yr⁻¹, and it exhibits a RV of −334 ± 4 km s⁻¹. The cluster follows a retrograde-prograde eccentric (e = 0.76_−0.14^+0.10) orbit, confined within the Galactic plane (|Z|_max = 1.0_−0.32^+0.45 kpc) and inside the bar's radius of influence (R < 5 kpc), with a pericenter of r_peri = 0.6_−0.2^+0.3 kpc and an apocenter of r_apo = 4.5_−1.2^+2.5 kpc. Conclusions. These orbital properties, combined with its ancient age and low metallicity, strongly support an in situ origin for VVV-CL001 and likely membership of the disk GC system that was captured by the potential of the bar during its formation. Thus, VVV-CL001 emerges as a fossil remnant of the earliest phases of Galactic assembly and a valuable tracer of the population that contributed to the formation of the inner thick disk and bulge, which are likely part of the main progenitor of the MW. Our study highlights the relevance of detailed chemo-dynamical analyses in unveiling the origin of GCs in the inner Galaxy.

High five from ASTEP: Three validated planets and two eclipsing binaries in a diverse set of long-period candidates

First Author: Rea, Erika
Instruments: HARPS
ProgramIDs: 1102.C-0923, 109.239V, 112.25W1, 115.286G, 112.261U, 108.22A8, 110.23YQ, 114.27CS, 106.21ER, 0104.C-0413
BibCode: 2026A&A...711A..86R

Context. We present the analysis of five long-period TESS Objects of Interest (TOIs), all orbiting Sun-like stars, with orbital periods exceeding one month. Initially identified by the Transiting Exoplanet Survey Satellite (TESS), we extensively monitored these targets with the Antarctic Search for Transiting Exoplanets (ASTEP), supported by other facilities in the TESS Follow-up Observing Program (TFOP) network. Aims. These targets occupy a relatively underexplored region of the period-radius parameter space, offering valuable primordial probes for planetary formation and migration as warm planets better maintain their evolutionary fingerprints. Methods. To characterise these systems, we leveraged high-resolution speckle imaging to search for nearby stellar companions, and refine stellar parameters using both reconnaissance spectroscopy and spectral energy distribution (SED) fitting. We combined TESS photometry with high-precision ground-based observations from ASTEP, and when available, included additional photometry and radial velocity data. We applied statistical validation to assess the planetary nature of each candidate and used allesfitter to jointly model the photometric and spectroscopic datasets. Results. We validate the planetary nature of three TOIs, including the two warm Saturns TOI-4507 b (8.2 R_⊕, 104 d) and TOI-3457 b (10.0 R_⊕, 32.6 d), as well as the warm sub-Neptune TOI-707 b (2.4 R_⊕, 52.8 d). The remaining two candidates are most consistent with eclipsing binaries, namely TOI-2404 and TOI-4404. Conclusions. These results help populate the sparse regime of warm planets, which serve as key tracers of planetary evolution, and demonstrate ASTEP's effectiveness as a ground-based follow-up instrument for long-period systems.

Constraints on Binarity for the Extreme Oe Variable Star AzV 493

First Author: Oey, M. S.
Instruments: FLAMES, GIRAFFE, XSHOOTER
ProgramIDs: 112.25D1, 109.22V0, 112.25R7
BibCode: 2026PASP..138g4202O

The extreme Oe star AzV 493 is known to show unusual photometric and spectroscopic variability that suggest the presence of an unseen companion in a highly eccentric and long-period (7.3 or 14.6 yr) orbit. We obtained a Chandra/ACIS observation near the putative periastron for the 7.3 yr orbit to test for transient X-ray emission that would confirm its binary nature. Our data only place an upper limit to the X-ray luminosity of L_X < 2.5 × 10³³ erg s⁻¹ based on the 0.5─8 keV flux limit. Additionally, we obtained 4 new spectroscopic observations with the M2FS spectrograph at Magellan and 20 archive FLAMES/GIRAFFE and X-Shooter spectra from ESO/VLT to further constrain the possibility of radial velocity (RV) variation. Statistical analysis of the RV measurements yields inconclusive results regarding the existence of variations. We discuss possible mass limits for a potential companion, which may be a black hole, in the event that the variations are real. The violet-to-red Balmer ratio has also recently inverted, which may be a further indication of a companion.

A deep study of the spiral galaxy W2246f

First Author: Johnston, Evelyn J.
Instruments: MUSE
ProgramIDs: 109.2393, 106.21F0
BibCode: 2026A&A...711A.194J

Aims. In this era of large surveys and statistical studies of galaxies, the beauty in the details of individual galaxies is often lost. In this paper we present a deep study of the spiral galaxy W2246f with MUSE, exploring the spatially resolved stellar and ionised gas properties to understand how it formed and evolved over time. The unusually deep observations of this galaxy with MUSE give us a rare opportunity to study this phenomenon with a better spatial resolution than can normally be achieved with the current IFU surveys of galaxies at a similar redshift (z ∼ 0.09). Methods. We analyse the stellar and gas kinematics, as well as the spatially resolved stellar populations and gas properties, including gas metallicity and the dominant ionisation sources. The derived properties include the stellar mass, radial profiles of luminosity- and mass-weighted mean ages and metallicities, and ionised gas characteristics such as E(B − V), Hα extinction, dust-corrected Hα flux, oxygen abundance using the O3N2 calibrator, Hα luminosity, and the Hα-based star formation rate. Results. Analysis of the stellar populations revealed a negative metallicity gradient, and the mass-weighted ages showed uniformly flat ages across the disc while the luminosity-weighted ages show a negative gradient. We find that the gas metallicity and star formation rate density also drop in the central region of the galaxy where the older luminosity-weighted stellar populations are found. Analysis of the WHAN and WHaD diagrams reveal that in fact the central region is retired, while the rest of the disc is star-forming. Conclusions. We conclude that W2246f is a nice example of a central low-ionisation emission-line region (cLIER) galaxy, where the central kpc is dominated by old, metal-poor stars with little star formation. The cLIER emission is primarily powered by hot evolved stars, while the rest of the disc displays ongoing star formation. These findings are consistent with a scenario of inside-out quenching.

The IACOB project: XVI. Surface helium abundances in Galactic O-type stars: Indications for identifying binary interaction products

First Author: Simon-Diaz, S.
Instruments: FEROS
ProgramIDs: 089.D-0975, 087.D-0946, 086.D-0997, 083.D-0589, 081.D-2008, 073.D-0609, 077.B-0348, 079.D-0564
BibCode: 2026A&A...711A.151S

The presence of massive O-type stars with surfaces enriched by CNO-cycle products has been known since the early 1980s. For many years, internal rotational mixing was assumed to be the dominant mechanism responsible for this chemical contamination. However, accumulating evidence suggests that binary interaction may play an equally important, if not dominant, role.

X-shooter spectroscopy of giant stars in the nuclear star cluster

First Author: Origlia, L.
Instruments: XSHOOTER
ProgramIDs: 099.D-0258
BibCode: 2026A&A...711A.176O

Near-IR spectra of a homogeneous sample of 15 red giants in the Galactic nuclear star cluster, within 1.5 pc of SgrA*, have been acquired with X-shooter at the Very Large Telescope. From these spectra, line-of-sight radial velocities and chemical abundances of iron, carbon, oxygen, and other alpha and light elements have been derived. By combining radial velocities from this study and proper motions from the literature, we computed the orbits of these stars, finding that they have been confined within 12 pc from SgrA* for their entire lifetime, thus strongly suggesting an in situ formation and evolution. Iron abundances between half and twice solar; approximately solar-scaled values within ±0.1 dex for α-elements, Ti, and V; some enhancement of [Na/Fe], [K/Fe], and [Al/Fe]; and some depletion of [C/Fe] with respect to the solar ratios have been measured. The inferred chemical abundance distributions are consistent with a formation from a gas enriched by type II and type I supernovae (SNe) over a prolonged timescale, closely matching those of the metal-rich populations of the inner bulge field and other complex stellar systems like Terzan 5 and Liller 1.

The carbon isotope ratio of β Pic b with high-resolution spectroscopy

First Author: González Picos, D.
Instruments: CRIRES
ProgramIDs: 114.27DX
BibCode: 2026A&A...711A..87G

Isotopic ratios trace the formation and evolution of planets and link their atmospheres to the chemistry of their natal protoplanetary discs. We measure ¹²C/¹³C = 58₋₁₅⁺¹⁸ in the atmosphere of the young super-Jupiter β Pic b from 11 nights of CRIRES+ K-band spectroscopy (ℜ ≍ 100 000) at the Very Large Telescope (VLT). We detect both ¹²CO and ¹³CO and constrain ¹²C/¹³C with a Bayesian retrieval jointly fitted with near-infrared photometry. The inferred ¹²C/¹³C is consistent with the present-day interstellar medium (ISM), is below the solar value, and is comparable to measurements in other young super-Jupiters. We also retrieve T_eff = 1629₋₂₈⁺³⁰ K, near-solar to mildly super-solar metallicity ([M/H] = 0.20₋₀₁₂^+0.16), a solar-like carbon-to-oxygen ratio (C/O = 0.52 ± 0.03), and tentative evidence for thick clouds. We analyse each night independently and combine the results of the six epochs with the highest signal-to-noise ratio (S/N), propagating night-to-night scatter into the final uncertainties. This provides an isotopic benchmark for a directly-imaged planet interior to the CO snow line.

The benefit of multiband high-resolution spectroscopic monitoring for studying stellar transients: The NGC 300 OT2008-1 UVES spectrum as a test case

First Author: Mason, Elena
Instruments: FORS1, UVES
ProgramIDs: 281.D-5016
BibCode: 2026A&A...711A.185M

Aims. This work aims to advocate for the benefit of high-resolution spectroscopic monitoring in the study of local group transients. Taking advantage of the experience gained through a vast and systematic study of transients such novae and non-compact stellar mergers that we monitored through panchromatic high-resolution spectroscopy, we show that a similar approach ─ i.e., a change of paradigm in the observing strategy and the analysis ─ in the study of a number of (local group) transients would be advantageous. Methods. As an exemplary analysis, we focus on the optical transient NGC 300 OT2008-1. Searching the ESO archives, we found a low-resolution (FORS) and a high-resolution (UVES) spectrum that were separated by only one day with no changes between them. We reduced and analyzed each spectrum, comparing the different information accessible in the two cases. Results. The independent analyses of the FORS and UVES spectra show that in the low-resolution spectra we can securely identify only a small sample of lines and are unable to correctly characterize the ejecta energetics, which remain at the level of speculation. Instead, in the high-resolution data, we identify a larger sample of emission lines and analyze their profiles. This points to a complex geometry and ejecta dynamics that are simply impossible to infer in low-resolution spectra. Line profile studies are not possible with low-resolution spectra, and may lead to potentially misleading measures. Additionally, because of the limited information available from low-spectral-resolution data, the interpretation is compromised (e.g., full-width-at-half-maximum measurement of unresolved lines), and the formulation of any realistic physical scenario hindered. The analysis is, thus, limited to parameter fitting to oversimplified, biased, standard models. On this occasion only one epoch was available, but monitoring is fundamental to characterize the transient evolution. In particular, since, based on the UVES spectrum, we propose a new very specific scenario, we discuss how it could have been confirmed or dismissed thanks to high-resolution spectroscopic monitoring. Low- and high-resolution spectra serve different but complementary purposes. With low resolution one does bolometric-like studies (spectral energy distribution, or strengthening or weakening of the major transitions), while with high resolution one does dynamics and precise physical characterization. We also show examples from our past works, on different types of transients for which it was possible, by monitoring them with high-resolution spectroscopy, to disentangle the various components, constrain their physical parameters and the energy source involved, and derive the ejecta dynamics.

A MUSE View of the Optical Torus within the Supernova Remnant 1E 0102.2─7219

First Author: Suherli, Janette
Instruments: MUSE
ProgramIDs: 0104.D-0092
BibCode: 2026ApJ..1006...52S

We present new Multi Unit Spectroscopic Explorer (MUSE) Narrow Field Mode with adaptive optics observations of the optical torus surrounding a central compact object candidate within the oxygen-rich supernova remnant 1E 0102.2─7219 located in the Small Magellanic Cloud. These data provide nearly an order-of-magnitude improvement in spatial resolution over previous MUSE Wide Field Mode observations. The improved spatial resolution resolved the previously identified torus into a cavity-like structure with a sharply defined inner edge and diffuse, outer filamentary substructure. The emission shows continuous velocity connectivity, broad intrinsic line widths, and cospatial contributions from neutral and partially ionized species, including O I, Ne I, [O I], [O II], and [O III]. Spatially resolved line-ratio maps indicate that the emission arises from a multiphase, nonequilibrium medium rather than a single homogeneous component. Comparison with photoionization and shock models shows that no single-component model within the explored parameter space can simultaneously reproduce both the strong neutral and high-ionization diagnostics, indicating that multiple physical conditions must coexist. We favor an interpretation in which shocks propagating through density inhomogeneities in the ejecta shape the observed morphology and excitation, while also considering alternative mechanisms linked to the central source, binary evolution, or interaction with an embedded object within the remnant.

Looking into the faintEst WIth MUSE (LEWIS): Exploring the nature of ultra-diffuse galaxies in the Hydra-I cluster: VI. A star-forming UDG in Hydra I: A rare UDG or a transition phase

First Author: Rossi, Luca
Instruments: MUSE
ProgramIDs: 108.222P
BibCode: 2026A&A...711A.149R

Context. This paper presents a detailed analysis of a gas-rich star-forming ultra-diffuse galaxy (UDG) as part of the ESO Large Programme Looking into the faintEst WIth MUSE (LEWIS). Among the UDGs in the LEWIS sample, UDG 6 is the only galaxy that hosts a significant amount of ionised gas with evidence of emission lines, suggesting recent star-forming activity. Aims. The main goal of this work is to constrain the formation history of this UDG by comparing its properties with the main formation scenarios proposed for this extreme class of galaxies. Methods. We adopted integral field spectroscopy from MUSE to derive the morphology and the structural properties of the stellar and gas components of UDG 6. We applied spectral fitting and Voronoi tessellation algorithms to the MUSE data-cube to derive the kinematics and properties of the gas and stellar component, explore gas dynamics, and characterise emission lines. Moreover, we derived the properties of the globular cluster (GC) populations by applying a multi-band spectrophotometric analysis. Results. We confirmed that UDG 6 is a member of the Hydra I cluster and that it has a systemic velocity of V_{sys, *} ∼ 3580 km s⁻¹. It is characterised by a regular and elongated shape and contains a significant dust content (A_V = 1.2 ± 0.5 mag), a metal-poor (12 + log₁₀(O/H) = 7.7 ± 0.2 dex) ionised gas fraction (f_gas = 0.24 ± 0.08), and an underlying old-to-intermediate (≳3 Gyr) stellar component. Evidence of local and clumpy star-forming activity has been revealed through the analysis of emission line ratios, and an arc-like tidal feature was discovered from unsharp masking analysis. The number counts of GCs in UDG 6 is N_GC = 0.2 ± 5.4. Conclusions. Similar to the other UDGs in LEWIS, UDG 6 might originate from a "puffed-up dwarf" whose stellar content has been stretched out to larger radii, passively evolving into a more diffuse galaxy. Since UDG 6 is located in a dynamically active region of the cluster characterised by tidal features and stripping phenomena, we suggest that the environmental processes have played a role in shaping its properties. A tidal interaction with a nearby galaxy might have triggered recent star-formation activity without dramatically altering the coherent gas rotation in UDG 6.

NGTS-39 b: a 58 d transiting warm Jupiter in an eccentric orbit

First Author: Apergis, Ioannis
Instruments: HARPS
ProgramIDs: 116.29B6, 112.261U, 116.28XG
BibCode: 2026MNRAS.550g1271A

We report the discovery and characterization of NGTS-39 b (TIC 453147896 b), a warm Jupiter transiting a Sun-like star on a 58.2 d, eccentric (e =

$0.386\pm 0.019$

) orbit. NGTS-39 b was first identified from a Transiting Exoplanet Survey Satellite single transit event, and subsequently confirmed with NGTS photometry and radial velocity measurements from CORALIE and HARPS. The host star is a bright (

$T_{\mathrm{mag}}$

= 11.02) F9 dwarf with effective temperature of T_eff =

$6053_{-30}^{+67}$

K. NGTS-39 b is a Jupiter-sized gas giant with a radius of

$1.088\pm 0.012$

R_J and a mass of

$1.467\pm 0.081$

M_J. Its equilibrium temperature is

$519_{-5}^{+6}$

K, placing it between short-period hot Jupiters and cold, Jupiter-like giants. The high orbital eccentricity and intermediate equilibrium temperature of NGTS-39 b make it a valuable test case for formation and migration models, particularly in the poorly sampled regime of long-period gas giants. The RV data show a linear trend of

$\dot{\gamma } = -17.75$

m s

$^{-1}$

, which indicates the presence of an outer companion. The discovery of NGTS-39 b contributes to the small but growing population of transiting warm Jupiters with P> 50 d orbiting bright stars.

The small transiting planet population revealed by ESPRESSO with extreme precision radial velocities

First Author: Hobson, M. J.
Instruments: ESPRESSO
ProgramIDs: 112.25BG, 108.2254, 110.24CD, 106.21M2, 1102.C-0958, 1104.C-0350, 0102.C-0456, 1102.C-0744
BibCode: 2026A&A...711A.198H

Context. Small planets are extremely common in the Galaxy, including planets with masses and radii between those of Earth and Neptune. Characterising the mass of such planets requires ultra-precise radial velocities. The ESPRESSO spectrograph was designed and built for this purpose. Aims. We present an overview of the ESPRESSO Guaranteed Time Observations transit follow-up sub-programme, which aimed to confirm and characterise small transiting planet candidates from the K2 and TESS space missions. Methods. We analysed the global stellar and planetary properties of the sample of 65 planets in 30 systems characterised by this subprogramme. This includes six systems presented in this paper, for which we either obtain only the upper mass limits or provide updates to previously published parameters. We also placed this sample in the context of the overall population of precisely characterised small planets. Results. After separating the population into insolation regimes, we find a tentative mass threshold at ≃6 M_⊕ for the rocky to volatile-rich composition transition in the medium-insolation regime, along with a population of likely stripped massive rocky planets in the high-insolation regime. Likewise, we find a correlation between planet mass and stellar metallicity, with more massive planets hosted by more metal-rich stars. We also explored the radius valley, finding that planets below the gap have a tighter mass distribution. We compared planetary masses with typical protoplanetary disk masses, drawing tentative conclusions about likely formation conditions. We also discuss the impact of our observing strategy on our results. Conclusions. The ESPRESSO transit follow-up sub-programme has been highly productive in characterising a diverse population of small planets, which has enabled us to identify population-level features. Likewise, the lessons learned from this sub-programme will be valuable for PLATO follow-up planning.

The breaking of cold traps and onset of titanium in ultra-hot Jupiter atmospheres: WASP-189b in context

First Author: Pelletier, S.
Instruments: HARPS, NIRPS
ProgramIDs: 111.2506
BibCode: 2026A&A...711A.119P

Context. Condensates are ubiquitous to all Solar System planets with significant (>10 mbar) atmospheres. The same is true for most exoplanets with characterised atmospheres, with even ultra-hot exoplanets being able to form clouds on their cooler nightsides. One high-interest condensate is titanium, a highly refractory element that as an oxide (TiO) is a potent optical absorber long believed to be a driver of thermal inversions in highly irradiated exoplanet atmospheres. Observations have shown that some ultra-hot Jupiters have strong thermal inversions despite being significantly Ti-depleted, likely due to cold trapping, raising doubts about whether TiO is the main cause of their inverted temperature structures. Aims. Our aim was to retrieve the titanium-to-iron ratio of the dayside atmosphere of the ultra-hot Jupiter WASP-189b to determine whether the full titanium budget is accounted for in the gas phase. Methods. We analysed thermal emission observations of WASP-189b taken with the HARPS and NIRPS spectrographs using different atmospheric retrieval prescriptions to infer the planet's atmospheric thermal structure and composition. Results. We observed Fe and Ti signals in cross-correlation and measured a sub-solar Ti/Fe ratio for WASP-189b using both free and chemical equilibrium retrieval approaches. We find the Ti/Fe of the planetary atmosphere to be between 28% and 81% (1-σ bounds) that of the stellar value. Conclusions. The slight underabundance of Ti with respect to Fe on the dayside atmosphere of WASP-189b suggests that some titanium is missing from the gas phase, potentially due to a partial nightside cold trap. In the context of the ultra-hot Jupiter population, the onset of titanium in exoplanetary atmospheres appears to occur progressively, coinciding not with when thermal inversions begin but rather when the vapourisation threshold of titanium is reached on the nightside.

The SPHERE infrared survey for exoplanets (SHINE): V. Full sample characterization

First Author: Squicciarini, V.
Instruments: SPHERE
ProgramIDs: 113.2689, 111.24QL, 1104.C-0416, 110.240D
BibCode: 2026A&A...711A.136S

Context. Unbiased surveys of large stellar samples are the prime means through which the prevalence of exoplanets can be derived, and crucial constraints to planet formation models can be set. Direct imaging (DI) is ideally positioned to probe the outer regions (5─300 au) of planetary systems, providing complementary information to techniques such as transits and radial velocities. Aims. We present the full sample of the SpHere INfrared survey for Exoplanets (SHINE), the second largest DI campaign to date. SHINE observed 460 stars between 2015 and 2023 thanks to the guaranteed time observations (GTO) allocated by ESO to the SPHERE consortium at VLT. The goal of this paper is to homogeneously derive the stellar properties of the targets and to define a subsample of young single hosts to be used as a starting point for the final statistical analysis of the survey. Methods. Stellar ages were determined based on kinematic indicators (such as the membership to young moving groups), age diagnostics (lithium abundance, rotation, and activity), and isochrone fitting. A thorough vetting for binarity was undertaken combining astrometric, spectroscopic, and imaging data. Results. A subsample of 333 stars, covering a large extent of stellar ages and masses, was constructed. Selection criteria, global features, as well as the properties of individual stars are reported and discussed.

Disruption of a giant: spectroscopic identification of members in the periphery and tidal tails of ω Centauri

First Author: Kuzma, P. B.
Instruments: FLAMES, GIRAFFE
ProgramIDs: 108.22MM
BibCode: 2026MNRAS.550g1147K

$\omega$

Centauri (

$\omega$

Cen, NGC 5139) is one of the most enigmatic globular clusters in the Milky Way, with the recent detection of tidal tails adding further to its complexity. We report the results of a spectroscopic study of stars in the outer regions of

$\omega$

Cen, which provides an improved characterization of the cluster periphery and confirms the existence of tidal tails. Our targets, which lie in six VLT/FLAMES fields sampling six degrees across the sky, are selected using a Bayesian inference technique. We confirm 157 members of

$\omega$

Cen based on line-of-sight velocity and [Fe/H] measurements, indicating an overall success rate of 93 per cent. We trace stars along the tidal tails to a cluster-centric radius of 3.2 deg, identifying five members in the debris and additional lower-probability candidates. The analysis of the kinematics and metallicities of the new members provides evidence of continuity in these properties from the bound component of the progenitor cluster into its tidal debris. We find that the metallicities of stars in the peripheral regions and tidal tails of

$\omega$

Cen are broadly consistent with those in the Fimbulthul stream to which the cluster has been previously linked. Our study provides a glimpse of the promise of new and forthcoming wide-field multi-object spectrographs for advancing understanding of tidal structures around Milky Way globular clusters.

Evolution of dust attenuation in star-forming galaxies with UV slope, stellar mass, and redshift out to z∼5

First Author: Wijesekera, J. V.
Instruments: VIRCAM
ProgramIDs: 179.A-2005, 179.A-2006
BibCode: 2026A&A...711A.189W

Context.To set reliable constraints on the dust-obscured portion of star formation across cosmic time, an accurate calibration of the so-called infrared excess (IRX ≡ L_IR/L_UV) and its dependence on intrinsic galaxy properties is required. While the local IRX-β relation (where F_λ ∝ λ^β) has been widely used to correct for the effects of dust absorption and scattering, many recent high-redshift works show significant inconsistencies. They are most likely caused by differences in the assumed attenuation curves, dust temperatures, and galactic star-to-dust relative morphologies. Aims. We found a dependence of the IRX on the UV slope β, stellar mass M_*, and redshift out to z ≃ 5. We also established consistent functional relations that can be used for correcting the UV/optical-selected galaxy samples for the effects of dust absorption. Methods. This work is based on a K-band selected sample of ∼10⁵ star-forming galaxies detected in the UDS and COSMOS fields. Quiescent sources and known starbursts have been removed, while the IR luminosities were established via stacking in FIR Herschel and JCMT maps. The UV slopes were determined from the spectral energy distribution (SED) fits and stacked IRX values were derived by taking the median of individual IRX measurements in bins of β, M_*, and redshift. Results. While our best-fit IRX-β relation is consistent with a Calzetti-like attenuation curve at β ≳ −1, at bluer values, the IRX appears to increase with redshift due to different mass-completeness limits imposed. When deriving the IRX-β relation in stellar-mass bins, a systematic trend was found, where the effective slope of the attenuation law becomes progressively shallower with increasing mass. We incorporated this into the IRX-β relation through the slope of the underlying reddening law, dA₁₆₀₀/dβ, which is a quadratic function of log(M_*/M_⊙). Expressing IRX as a function of the stellar mass, we find a tight correlation, with IRX rising monotonically with mass, while exhibiting a clear high-mass turnover at z ≲ 2 − 3, consistent with suppressed cold-gas accretion and dust growth in massive systems.

Global and Local Infall in the ASHES Sample (GLASHES). II. Asymmetric Line Profiles Around Dense Cores in 70 μm Dark Massive Clumps

First Author: Morii, Kaho
Instruments: ALMA_Band_6
ProgramIDs: 2018.1.00299.S, 2023.1.01150.S, 2024.1.01505.S
BibCode: 2026ApJ..1004..207M

Gravitational collapse is fundamental to star formation, yet direct kinematic evidence of infall at the core scale in high-mass star-forming regions remains poorly constrained. We present the first large-scale statistical study of infall signatures in 304 dense cores within 24 massive 70 μm dark clumps from the Global and Local Infall in the ASHES Sample survey. Using Atacama Large Millimeter/submillimeter Array Band 6 observations of the optically thick tracers HCO⁺ and HNC (J = 3─2), we systematically characterize blue asymmetry line profiles indicative of infalling motions. We employ two complementary metrics, the velocity difference parameter (δ_v) and the asymmetry parameter (A), to quantify infall signatures, finding consistent results across both tracers. Blue asymmetry profiles are detected in ∼50%─60% of cores (δ_v < 0 or A > 0). Spectral classification reveals that ∼60% of cores exhibit double-peaked profiles, and 34% and 39% show blue asymmetry profiles in HCO⁺ and HNC, respectively, with the percentage increasing with core mass and surface density. Accounting for geometric effects that can obscure infall signatures, our results suggest that gravitational collapse is prevalent in and around the cores. Importantly, infall signatures are detected from the prestellar stage and become more dominant as the core's evolution proceeds. Even cores with virial parameters α_vir > 2 show infall signatures, suggesting that external compression may trigger collapse in addition to self-gravity or that line width may include inward motion in addition to turbulence. Furthermore, a moderate correlation between clump-scale and core-scale asymmetry supports a hierarchical collapse scenario, implying a dynamic and multiscale process of high-mass star formation.

Morphological Complexity of NGC 628—A Multiwavelength Multiscale Analysis Using the Ordinal Pattern Framework

First Author: Chanu, Athokpam Langlen
Instruments: ALMA_Band_6
ProgramIDs: 2012.1.00650.S
BibCode: 2026ApJ..1003...50C

As statistical systems, galaxies exhibit a rich interplay between organized structure and stochastic fluctuations across a broad range of spatial scales. This duality motivates the need for quantitative frameworks capable of capturing their morphological complexity. The ordinal patterns framework, along with its associated statistical measures: permutation entropy (H), disequilibrium (D_E), statistical complexity (C), and ordinal network node entropy, has recently emerged as a powerful tool for analyzing such complexity in physical systems. We apply this framework in a multiwavelength, multiscale analysis of the galaxy NGC 628, utilizing observations in the near-ultraviolet, near-infrared, mid-infrared, and millimeter bands. Our results reveal a characteristic spatial scale of approximately 200 pc, marking the transition from small-scale structures influenced by star formation and stellar feedback to larger-scale morphology governed by the galaxy's dynamics. Furthermore, we find that the C versus H trajectories for all wavelengths converge toward a common attractor curve, consistent with the behavior of isotropic Gaussian random fields. This convergence suggests a universal statistical behavior in galactic structure at large scales, despite the differing physical processes traced by each wavelength.

GOALS-JWST: resolved multiphase molecular gas in IRAS 20551-4250 using JWST and ALMA

First Author: Kakkad, D.
Instruments: ALMA_Band_6, MUSE
ProgramIDs: 2022.1.01262.S, 095.B-0049
BibCode: 2026MNRAS.549ag781K

Studying the content and distribution of molecular gas (H

$_{2}$

) provides key insights into how feedback from active galactic nuclei (AGNs) and star formation influences galaxy evolution, since molecular gas is the primary fuel for star formation. Ultra-luminous infrared galaxies (ULIRGs) are ideal candidates to study how AGNs and/or starbursts affect the interstellar medium due to their intense AGN and star-forming activity. We present spatially resolved multiphase molecular gas study of IRAS20551-4250, a nearby (

$z=0.0429$

) ULIRG, using James Webb Space Telescope (JWST)/MIRI-MRS and ALMA. Mid-infrared diagnostics do not rule out the presence of AGNs in IRAS20551-4250. [O III]

$\lambda$

5007 in VLT/MUSE data reveal ionized gas outflows with

$w_{80}^{\rm [OIII]} \sim 790$

km s

$^{-1}$

and

$\dot{M}_{\rm out}^{\rm [OIII]}\lt 0.01$

$_{\odot }$

$^{-1}$

. No outflows are observed in either molecular phases. JWST/MIRI-MRS data reveal several rotational transitions of warm H

$_{2}$

$\sim 500\!-\!1400$

K) within the central

$\sim 4\times 4$

kpc

$^{2}$

region. Excitation temperature maps suggest that the warm H

$_{2}$

is primarily heated by UV radiation from the central source. The CO-based cold molecular component dominates the molecular gas mass, accounting for >95 per cent of the total molecular gas mass. Warm H

$_{2}$

maps show two tidal tails and the velocity centroid maps show disturbed non-rotational motions and a systematic gradient across the field of view, similar to that of ALMA CO-based cold molecular gas and consistent with a late-stage merger. Together, our analysis indicate that the molecular gas composition in IRAS20551-4250 is consistent with ongoing star formation in the host galaxy and the outflows observed in ionized gas phase appear insufficient to expel the molecular gas or quench ongoing star formation.

ALMA Observations of [O I] 145 μm and [N II] 205 μm Emission Lines from Star-forming Galaxies at z ∼ 7

First Author: Fudamoto, Yoshinobu
Instruments: ALMA_Band_5, ALMA_Band_6
ProgramIDs: 2021.1.00247.S, 2022.1.00446.S, 2022.1.00999.S, 2022.1.01384.S
BibCode: 2026ApJ..1004..194F

We present results of new observations of [O I] 145 μm and [N II] 205 μm emission lines from four star-forming galaxies at redshifts between z = 6.58 and 7.68 that have previous detections of [C II] 158 μm and dust continua. Using the Atacama Large Millimeter/submillimeter Array, we successfully detect [O I] 145 μm emission from all targets at >4σ significance. However, [N II] 205 μm emission is undetected in all galaxies (signal-to-noise ratio < 3.5σ) except for a tentative detection from A1689-zD1. From the observed high [C II]/[N II] emission line ratios (≳20−80), we find that most of the [C II] 158 μm emission arises from neutral gas regions (3σ lower limits of ≳74%−96%). From [O I] 145 μm, [C II] 158 μm lines, and IR luminosities, we estimate the neutral gas densities of n_H = 10^3.5─10⁶ cm⁻³ and the far-UV (FUV) radiation strengths of G₀ ∼ 10^2.5─10³. While the neutral gas densities are similar to those of high-redshift starburst galaxies, the FUV strengths are lower compared to both local and high-redshift starbursts. Finally, we estimate atomic hydrogen masses using [O I] 145 μm emission lines and the oxygen abundances measured from recent JWST observations. We find gas mass ratios of f_gas ∼ 0.3─0.8, which are similar to earlier studies using [C II] 158 μm. Starting from this pilot observation, future large [O I] 145 μm emission line surveys will provide us with currently little-known neutral gas properties of star-forming galaxies in the early Universe.

The relationship between accretion and ionized ejection among young stellar objects in the Coronet cluster

First Author: Ghosh, Arpan
Instruments: KMOS
ProgramIDs: 093.C-0657
BibCode: 2026MNRAS.546ag154G

We present results from a coordinated, multi-epoch near-infrared and centimetre radio survey of young stellar objects (YSOs) in the Coronet, aimed at probing the connection between mass accretion and ionised mass-loss. Using VLT-KMOS, we detect Br

$\gamma$

emission in 5 of the 26 targets, which also exhibit 3.3-cm continuum emission in VLA images, consistent with partially ionised jets. For seven additional sources, stringent flux upper limits were obtained. The derived accretion and ionized mass-loss rates for class I and class II YSOs follow a sublinear correlation

$\dot{M}_{\mathrm{ion}} \propto \dot{M}_{\mathrm{acc}}^{0.3}$

, consistent with previous results for class II YSOs but extended here to earlier stages. Multi-epoch observations reveal modest variability in both tracers but no clear temporal correlation between accretion and ejection within time-scales of a few months. The ratio

$\dot{M}_{\mathrm{ion}}/\dot{M}_{\mathrm{acc}}$

shows an anticorrelation with

$\dot{M}_{\mathrm{acc}}$

, increasing with time from class I YSOs to class II YSOs, suggesting an increase in jet-launching efficiency or ionization fraction with evolution. These findings support a direct connection between accretion and outflow across the

$\sim$

Myr time-scale of YSO evolution, while highlighting the complexity of their short-term interplay.

Chemodynamics of Boötes I with S⁵: Revised Velocity Gradient, Dark Matter Density, and Galactic Chemical Evolution Constraints

First Author: Sandford, Nathan R.
Instruments: FLAMES, GIRAFFE
ProgramIDs: 182.B-0372, 185.B-0946
BibCode: 2026ApJ...998...47S

We combine new spectroscopic observations of the ultrafaint dwarf (UFD) galaxy Boötes I (Boo I) from the Southern Stellar Stream Spectroscopic Survey (S⁵) with ∼15 yr of archival spectroscopic data to create the largest sample of stellar kinematics and metallicities to date for any Milky Way UFD. Our combined sample includes 148 members extending out to ∼7 half-light radii (r_h), including 24 newly confirmed members, 18 binary candidates, 15 RR Lyrae stars, and 92 [Fe/H] measurements. Using this larger and more spatially extended sample, we provide updated constraints on Boo I's systemic properties, including its radial population gradients. Properly accounting for perspective rotation effects in a UFD for the first time, we detect a 4σ line-of-sight velocity gradient of 1.2 ± 0.3 km s⁻¹ rh−1 aligned along Boo I's orbit and discuss its potential tidal origins. We also infer a metallicity gradient of −0.10 ± 0.02 dex rh−1 in agreement with previous studies. Using an axisymmetric Jeans model, we provide updated constraints on Boo I's dark matter density profile, which weakly favors a cusped ( γ=1.0−0.6+0.5 ) dark matter profile. Lastly, we reanalyze Boo I's metallicity distribution function with a one-zone galactic chemical evolution model and place new constraints on its rapid, inefficient star formation and strong galactic outflows.

The Discovery of an Active Wind from the Milky Way's Central Black Hole

First Author: Gorski, Mark D.
Instruments: ALMA_Band_6
ProgramIDs: 2016.1.00870.S, 2017.1.00995.S, 2019.1.01559.S
BibCode: 2026ApJ..1004L...7G

Every large galaxy has a black hole in its center. The interaction between the black hole and its host profoundly shapes galactic evolution and the Universe as a whole. The key features of this interaction are black hole jets—or more generally, winds—which every black hole must have. Despite the proximity and importance of our Galaxy's central black hole, Sagittarius A* (Sgr A*), the active wind from it has eluded scientists for over half a century. Here we report the discovery of a large active wind from Sgr A* using unprecedentedly deep (T_b ∼ 30 mK) and high angular resolution (≲0 .″ 25) observations with the Atacama Large Millimeter/Submillimeter Array (ALMA). We detect a large conical clearing in the cold molecular gas surrounding Sgr A* that is at least 1 parsec long and has a ∼45° opening angle. The morphology and energetics of this structure are consistent with active clearing of gas by a hot wind from Sgr A*.

Modeling the Milky Way Circumnuclear Disk: Rosettes and Rings

First Author: Ukani, Asad
Instruments: ALMA_Band_7
ProgramIDs: 2017.1.00040.S
BibCode: 2026ApJ..1004..171U

The Milky Way Galactic Center hosts a ∼4 × 10⁶ M_⊙ supermassive black hole (SMBH), Sagittarius A* (Sgr A*). The dominant structures in its immediate vicinity are the nuclear star cluster (NSC), whose enclosed mass at 2 pc is approximately half that of the SMBH, and the circumnuclear disk (CND)/ring, which extends between ∼0.5 pc and ∼3 pc from Sgr A* and is the largest reservoir of molecular gas in this region. Existing models of the CND commonly use one circular orbit to describe the motion of its gas. Here, we explore a much broader range of models. In the combined potential of Sgr A* and the NSC, we consider non-Keplerian rosette orbits as well as a circular disk, which is formed using a finely spaced set of concentric rings. For both systems, we test various inner/outer radii, inclinations, and position angles, sampling a total of ∼3.3 × 10⁵ models. We then conduct mock observations of all models to construct velocity maps, which we compare with HCN (J = 1─0) observations of the CND. We find that the best-fitting model is a circular disk with inner and outer radii of 1.0 pc and 2.9 pc, an inclination of i = 60°, and a position angle of PA = 35°.

Multiscale Gas Structure and Dynamics in an Extragalactic Central Molecular Zone

First Author: Wang, Liam M.
Instruments: ALMA_Band_7
ProgramIDs: 2021.1.00059.S, 2022.1.00159.S
BibCode: 2026ApJ..1003..231W

The structures and dynamics of the interstellar medium are governed by a combination of self-gravity, external gravity, and various sources of ordered and random motions on different spatial scales. This paper uses Atacama Large Millimeter/submillimeter Array CO (3─2) observations at 0.″1≍5 pc resolution to examine the scale dependence of molecular gas structure and dynamics in the central molecular zone (CMZ) of a nearby galaxy, NGC 3351. We use the dendrogram technique to characterize hierarchical molecular gas structures spanning two decades in spatial scales and measure their size, gas mass, and velocity dispersion. Their size─line width relation shows a power-law slope of 0.58, comparable to measurements for CMZs in other galaxies and suggestive of significant contribution from ordered motion on large scales. We further decompose the observed velocity dispersion in each gas structure into ordered versus random motions. The former appears stronger in gas structures at ≳30 pc, while the latter becomes more dominant at ≲30 pc. Modulo uncertainties with the CO-to-H₂ conversion factor, the estimated gravitational free-fall time is comparable to the crossing time of ordered motions for structures on all spatial scales, and both become longer than the crossing time of random motions at small, ≲10 pc scales. Our results highlight the varying sources and drivers of gas motions on different spatial scales in the CMZ of a Milky Way─like galaxy.

ALMA [C I] Image of the Circumnuclear Disk of the Milky Way: Inflowing Low-density Molecular Gas

First Author: Tanaka, Kunihiko
Instruments: ALMA_Band_3, ALMA_Band_8
ProgramIDs: 2013.1.00857.S, 2015.1.01040.S, 2016.1.00940.S, 2022.1.01219.S
BibCode: 2026ApJ...999..185T

We present Atacama Large Millimeter/submillimeter Array [C I] ³P₁─³P₀ imaging of the central 6.6 × 4.2 pc² region of the Galaxy encompassing the circumnuclear disk (CND). The data reveal low-density ( nH2∼103 cm⁻³) molecular gas with inward motion, widespread both inside and outside the CND. The normalized [C I] to CS 7─6 intensity difference decreases inwardly from R = 4 pc to 1.7 pc and azimuthally along the CND's rotation, likely tracing paths of low-density gas inflow. By projecting spaxels into orbital coordinates assuming a velocity field model, we identify four kinematic features: a pair of spiral outer streamers toward the CND, inner streamers extending to 0.5 pc from Sgr A^*, an outer disk at R ∼ 3─6 pc, and the rotating ring at R = 2 pc. P─P─V correlation between the inner streamers and H42α indicates gas supply to the mini-spiral through the western arc (WA) and northern arm (NA). The total inflowing mass is 1.5 × 10⁴ M_⊙, 1.7 times the mass of the rotating ring. The identified flows can be organized into two main pathways connecting the CND exterior and interior: "WA flow" feeding the mini-spiral WA via the CND, and "NA flow" bypassing the purely rotating orbit. The inflow rate along the former is approximately constant (0.1─0.16 M_⊙ yr⁻¹), implying a CND dwelling time comparable to its orbital period and supporting the CND's transient nature. We also identify two [C I]-bright clumps (CBCs) lacking dense-gas counterparts near the contact point between the northern outer streamer and the CND. Apparently intact against tidal disruption despite subcritical densities, the CBCs may represent a chemically young phase shortly after formation in colliding flows.

Breathless BEARS: [O III] 88 µm emission of dusty star-forming galaxies at z = 3−4

First Author: Bakx, T. J. L. C.
Instruments: ALMA_Band_10, ALMA_Band_7, ALMA_Band_8, ALMA_Band_9
ProgramIDs: 2021.1.00265.S, 2022.1.00145.S, 2022.1.00432.S, 2023.1.00750.S
BibCode: 2026MNRAS.546ag106B

We present [O III] 88

$\mu {\rm m}$

observations towards four Herschel-selected dusty star-forming galaxies (DSFGs;

$\log _{10} \mu L_{\rm IR} / L_{\odot } = 13.5 \!-\! 14$

$z = 2.9\!-\!4$

) using the Atacama Compact Array (ACA) in Bands 9 and 10. We detect [O III] emission in all four targets at

$\gt\, 3 \sigma$

, finding line luminosity ratios (

$L_{\rm [O_{III}]} / L_{\rm IR} = 10^{-4.2}$

$10^{-3}$

) similar to local spiral galaxies, and an order of magnitude lower when compared with local dwarf galaxies as well as high-redshift Lyman-break galaxies. Using the short-wavelength capabilities of the ACA, these observations bridge the populations of galaxies with [O III] emission at low redshift from space missions and at high redshift from ground-based studies. The difference in [O III] emission between these DSFGs and other high-redshift galaxies reflects their more evolved stellar populations (>10 Myr), larger dust reservoirs (

$M_{\rm dust} \sim 10^{9 - 11}$

$_{\rm \odot }$

), metal-rich interstellar medium (

$Z \sim 0.5\!-\!2$

$_{\odot }$

), and likely weaker ionization radiation fields. Ancillary [C II] emission on two targets provide

$L_\mathrm{[O\, {\small III}]}/L_\mathrm{[C\, {\small II}]}$

ratios at 0.3─0.9, suggesting that ionized gas represents a smaller fraction of the total gas reservoir in DSFGs, consistent with theoretical models of DSFGs as transitional systems between gas-rich, turbulent disks and more evolved, gas-poor galaxies. Expanding samples of DSFGs with [O III] emission will be key to place this heterogeneous, poorly understood galactic phase in its astrophysical context.

Methanol Line Diagnostics of Post-burst Physical Evolution in the High-mass Episodic Accretion Source G358.93−0.03

First Author: Liu, Meizhu
Instruments: ALMA_Band_5, ALMA_Band_6, ALMA_Band_7
ProgramIDs: 2018.A.00031.T, 2019.1.00768.S, 2021.1.00799.S
BibCode: 2026ApJ..1000...30L

We report multi-epoch Atacama Large Millimeter/submillimeter Array Band 5─7 observations of the high-mass episodic-accretion burst source G358.93−0.03, covering (sub-)millimeter CH₃OH masers, quasi-thermal lines, and continuum from 2019 April to 2022 January. Five new CH₃OH maser transitions (189.369, 220.401, 241.043, 293.464, and 330.794 GHz) were detected, all coincident with the brightest continuum core MM1. Together with nine previously known sub-millimetre masers, they exhibit a rapid intensity decline on 3 month timescales from 2019 April to July. In 2019 April, the maser spots form a ring-like pattern, matching the morphology of centimeter-wavelength counterparts observed in previous studies. Rotation diagram analysis of quasi-thermal CH₃OH lines reveals pronounced post-burst evolution in the gas envelopes of MM1 and MM3: both cores were heated due to the heat wave propagation induced by the episodic accretion from MM1 in 2019 October. These results establish that episodic accretion bursts in massive protostars trigger rich (sub)millimeter maser activity and drive radiative heat waves across their natal environments.

JWST Edge-on Disk Ice (JEDIce): Program Overview and Ice Survey Results

First Author: Bergner, Jennifer B.
Instruments: ALMA_Band_6, ALMA_Band_7
ProgramIDs: 2016.1.00771.S, 2022.1.01302.S, 2023.1.00634.S, 2023.1.00907.S
BibCode: 2026ApJ..1002...17B

The icy material within protoplanetary disks plays a central role in planet formation, yet remains poorly characterized by observations. We present 1.6─28 μm spectra of five disks obtained as part of the JWST Edge-on Disk Ice program, representing the largest survey of disk ices to date. The major ice species H₂O, CO₂, and CO are detected toward all disks, and exhibit a wide range of absolute optical depths and optical depth ratios across the sample. This is suggestive of a range of ice abundances and compositions, but quantitative constraints will require radiative transfer modeling. All disks exhibit ice features across the entire spatial region where the IR continuum is detected; vertically elevated ice grains therefore seem to be ubiquitous in disks. The CO ice is consistently dominated by apolar CO:CO₂ mixtures, implying that the disk ice compositions are neither completely reset nor pristinely inherited from the protostellar stage. The presence of these mixtures also suggests that entrapment may be important in shaping the spatial distribution of CO within the disks. Small molecules commonly seen in protostellar ices (CH₄, CH₃OH, and NH₃) are generally not detected in our sample, though tracers of ammonium salts (OCN⁻ and the 6.85 μm band) are common, potentially reflecting an evolution toward comet-like ice compositions. The spectra also contain a wealth of information about the micron-sized dust, atomic and molecular gas, and polycyclic aromatic hydrocarbon content, which together with the ice constraints will provide a comprehensive picture of the chemical, physical, and dynamical state of these systems.

Hadronic origin of the very high-energy gamma-ray emission from the low-luminosity AGN in NGC 4278

First Author: Shoji, Asahi
Instruments: ALMA_Band_6
ProgramIDs: 2022.1.01173.S
BibCode: 2026PASJ...78..166S

The Large High Altitude Air Shower Observatory has detected very high-energy (VHE) gamma-rays from NGC 4278, which is known to host a low-luminosity active galactic nucleus (AGN). Having only very weak radio jets, the origin of its VHE gamma-rays is unclear. In this paper we first show that NGC 4278 has a massive molecular cloud surrounding the nucleus by analyzing data taken with the Atacama Large Millimeter/submillimeter Array. We then assume that cosmic ray protons are accelerated in a radiatively inefficient accretion flow around the supermassive black hole, diffusing into the molecular cloud and producing gamma-rays and neutrinos via

$pp$

interactions. We model the gamma-ray spectra and find that the observations can be explained by such hadronic processes if the AGN activity was higher in the past than at present, and the diffusion coefficient in the molecular cloud is appreciably smaller than in the Milky Way interstellar medium. We also show that although the high-energy neutrinos co-produced with the gamma-rays are unlikely to be detectable even with IceCube-Gen2, the accompanying synchrotron X-ray emission due to pion-decay secondary electrons and positrons may be detectable in the future, providing a valuable test of our hadronic model.

Planetary-mass exosatellite detected around the substellar companion of a star

First Author: Hoy, Kevin
Instruments: CRIRES
ProgramIDs: 116.2AP9, 112.25HG, 114.271E
BibCode: 2026Natur.655..865H

Brown dwarfs occupy the mass regime between planets and stars. In systems containing both a star and a substellar companion (be it a brown dwarf or an exoplanet), a third object orbiting the companion can be called an exosatellite. Exoplanet satellites can be easily described as exomoons, but it is not clear if satellites of brown dwarf companions can be called the same, as the term lacks a formal definition. Despite more than 6,000 exoplanets being discovered¹, no exomoon has ever been confidently detected. Although there are candidates, they lack confirmation and remain controversial^{2, 3, 4─5}. In this work, we present evidence of an exosatellite orbiting the directly imaged brown dwarf companion CD-35 2722 B. Applying radial velocity analysis, the same technique used to discover the first exoplanet around a Solar-type star⁶, to VLT/CRIRES+ spectra of this brown dwarf, we find what appears to be the periodic signal of at least one orbiting satellite. This is the first time, to our knowledge, this technique has produced evidence of satellites around a companion brown dwarf. Our best-fitting model includes a satellite with a minimum mass of about 0.9 Jupiter masses and a period of around 170 days. Although it is uncertain whether this exosatellite will fulfil the presently undefined criteria for qualifying as an exomoon, it is a marked step towards that first uncontroversial detection, as advancing technology will allow the same method to be applied to less massive targets.

Magnetic fields in galactic environments probed by fast radio bursts

First Author: Khrykin, Ilya S.
Instruments: MUSE
ProgramIDs: 105.20HG, 110.241Y, 0104.A-0411
BibCode: 2026A&A...706A..11K

Fast radio bursts (FRBs) are extragalactic, bright, millisecond radio pulses emitted by unknown sources. FRBs constitute a unique probe of various astrophysical and cosmological environments via their characteristic dispersion (DM) and Faraday rotation (RM) measures that encode information about the ionised gas traversed by the radio waves along the FRB line of sight. In this work, we analysed the observed RM measured for 14 localised FRBs in the 0.05 ≲ z_frb ≲ 0.5 redshift range, in order to infer the total magnetic field, B, in various galactic environments. Additionally, we calculated f_gas ─ the average fraction of baryons in the ionised CGM. We built a spectroscopic dataset of FRB foreground galaxy halos, acquired with VLT/MUSE observations and by the FLIMFLAM collaboration. We developed a novel Bayesian statistical algorithm and used it to correlate information on the individual intervening halos with the observed RM_obs. This approach allowed us to disentangle the magnetic fields present in various environments traversed by the FRB sight lines. Our analysis yields the first direct FRB constraints on the strength of magnetic fields in the interstellar medium (ISM) ( B_host^local B host local ) and in the halos ( B_host^halo B host halo ) of FRB host galaxies, as well as in the halos of foreground galaxies and groups ( B_fg^halo B fg halo ). Assuming no field reversals, we find that the average magnetic field strength in the ISM of the FRB host galaxies is B_host^local = 5.4^1.1_−0.9μ B host local = 5 . 4 − 0.9 + 1.1 μ G. Additionally, we placed an upper limit on the average magnetic field strength in FRB host halos, B_host^halo ≲ 4.8 μ B host halo ≲ 4.8 μ G, and in foreground intervening halos, B_fg^halo ≲ 4.3 μ B fg halo ≲ 4.3 μ G. Moreover, we estimated the average fraction of cosmic baryons inside 10 ≲ log₁₀(M_halo/M_⊙) ≲ 13.1 halos to be f_gas = 0.45_−0.19^+0.21 f gas = 0 . 45 − 0.19 + 0.21 . We find that the magnetic field strengths inferred in this work are in good agreement with previous measurements. In contrast to previous studies that analysed FRB RMs and have not considered contributions from the halos of the foreground and/or FRB host galaxies, we show that halos can contribute a non-negligible amount of RM and must be taken into account when analysing future FRB samples.

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

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

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

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

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

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

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

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

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

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

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

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

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

Spatially Resolved Spectral Properties of M87* on Event Horizon Scales

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

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

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

High-resolution ALMA Imaging for a Gravitationally Lensed Quasar at z = 6.5: Constraining the Active Galactic Nucleus Contribution to Galactic-scale Dust Heating

The formation radius of HCN in O-rich asymptotic giant branch stars

Azimuthal brightness modulation reveals hidden rings in CI Tau

HOTDISK. Finding Massive Protostellar Disks with Water and Refractory Molecular Species

Nondetection of HC(S)SH: Estimating Upper Limits and Constraining Chemistry

SN 2021aaev: A Hydrogen-rich Superluminous Supernova with Early Flash and Long-lived Circumstellar Interaction in an Unusual Host Environment

ASPIRE: The Environments and Dark Matter Halos of Luminous Quasars in the Epoch of Reionization

GOTO identification and broad-band modelling of the counterpart to the SVOM GRB 250818B

From chemical space to observational priority: Predicting detectable molecules in IRC+10216

The converging gas flow around the infrared dark cloud G28.37

EIGER. VIII. First Stars Signatures in the Connection between O I Absorption and Galaxies in the Epoch of Reionization

Chasing the Tides: Searching for Orbital Decay Signatures in Transit Timing Data and Tidal Models for 20 Hot Jupiters

Reconstructing the Assembly of Massive Galaxies. III. Quiescent Galaxies Lose Angular Momentum as They Evolve in a Mass-dependent Fashion

Wide binaries without viable bound Newtonian orbits

Enhanced detection limits in the SHINE F150 survey through the regime switching model: Optimizing thresholds and investigating environmental noise

GATOS ─ XI. Excess dust heating in the narrow-line regions of nearby AGN revealed with JWST/MIRI

Gaia20dsk: A new MNor discovered by the GLORIOUS collaboration

2MASS Reprocessing. I. The Search for Faint Objects

VLT/SPHERE images of the candidate companion of Betelgeuse

GA-NIFS: interstellar medium properties and tidal interactions in the evolved massive merging system B14-65666 at z = 7.152

Exploring the interplay between molecular and ionized gas in H II regions

Evolution of the infrared luminosity function and its corresponding dust-obscured star formation rate density out to z ∼ 6

LRPayne: Stellar parameters and abundances from low-resolution spectra

Measuring the intergalactic medium correlation length at 5 < z < 6.1: A fast change at the end of reionization

TDCOSMO: XXIII. Measurement of the Hubble constant from the doubly lensed quasar HE 1104−1805

A JWST Paα Calibration of the Radio Luminosity─Star Formation Rate Relation at z ∼ 1.3

A Comprehensive Analysis of the Panchromatic Transmission Spectrum of the Hot-Saturn WASP-96 b: Nondetection of Haze, Possible Sodium Limb Asymmetry, Stellar Characterization, and Formation History

Infrared photometry and calcium triplet spectroscopy of the most metal-poor in situ globular cluster VVV-CL001

High five from ASTEP: Three validated planets and two eclipsing binaries in a diverse set of long-period candidates

Constraints on Binarity for the Extreme Oe Variable Star AzV 493

A deep study of the spiral galaxy W2246f

The IACOB project: XVI. Surface helium abundances in Galactic O-type stars: Indications for identifying binary interaction products

X-shooter spectroscopy of giant stars in the nuclear star cluster

The carbon isotope ratio of β Pic b with high-resolution spectroscopy

The benefit of multiband high-resolution spectroscopic monitoring for studying stellar transients: The NGC 300 OT2008-1 UVES spectrum as a test case

A MUSE View of the Optical Torus within the Supernova Remnant 1E 0102.2─7219

Looking into the faintEst WIth MUSE (LEWIS): Exploring the nature of ultra-diffuse galaxies in the Hydra-I cluster: VI. A star-forming UDG in Hydra I: A rare UDG or a transition phase

NGTS-39 b: a 58 d transiting warm Jupiter in an eccentric orbit

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

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

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

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

Chemodynamics of Boötes I with S⁵: Revised Velocity Gradient, Dark Matter Density, and Galactic Chemical Evolution Constraints