ESAWebb Picture of The Month

A pair of planet-forming discs

Fri, 03 Apr 2026 10:00:00 +0200

This month’s ESA/Webb Picture of the Month offers us a two-for-one on brand new stars — with some potential planets thrown in as well! This visual highlights views from the NASA/ESA/CSA James Webb Space Telescope of the protoplanetary discs Tau 042021 (left) and Oph 163131 (right), otherwise known by the catalogue numbers 2MASS J04202144+2813491 and 2MASS J16313124-2426281, respectively. Tau 042021 is situated around 450 light-years from Earth in the constellation Taurus, while Oph 163131 lies about 480 light-years away in Ophiuchus.

Protoplanetary discs like these appear around stars that have recently been born. When a clump of gas inside a larger molecular cloud collapses to form a star, unused gas and dust is left orbiting the star in a thick disc. Over time, this dust too collides and collapses, slowly forming planetesimals which can, in turn, develop into planets. The planetesimals which can’t make the jump to being a fully-fledged planet are left behind as asteroids and comets orbiting the star. Gas that isn’t consumed by this process is blown away by the new star’s radiation over the course of tens of millions of years, ending the protoplanetary disc. This is how our own Solar System formed in the distant past, creating the asteroids, comets, gas giants and terrestrial planets we know today. By observing other protoplanetary discs at a much earlier age, we can work out how this process worked for our own Solar System, and how the different kinds of planets we see across the galaxy could have formed.

The unique feature these two objects have in common is that, as we see them from our vantage point with Webb, they are oriented with the edge of the disc facing us. This means that the bright light from the young star in the centre is mostly blocked, and we see the fine dust that has risen out of the disc as a nebula above and below the disc, lit by reflected light from the star. Not only is this a beautiful sight, producing these images that resemble rainbow-coloured spinning tops in space, it’s essential for studying how these planet-forming discs are composed. The distribution of dust in the disc, both within it and above or below it, strongly affects where and how planets can form.

These images were created using data from Webb’s NIRCam and MIRI instruments, as part of Webb programme #2562 (PI F. Ménard, K. Stapelfeldt). With the broad infrared sensitivity of these two cameras, Webb can track dust grains of different sizes across the disc. The red, orange and green colours of the discs in these images indicate various sizes of dust grains as well as molecules such as hydrogen (H2), carbon monoxide (CO) and polycyclic aromatic hydrocarbons (PAHs).

Both images also feature data from the NASA/ESA Hubble Space Telescope, which shows visible light, mainly from the central star reflected off the fine, floating dust. The image of Oph 163131 also includes observations from the Atacama Large Millimeter/submillimeter Array (ALMA). Where Hubble and Webb each image tiny dust grains only micrometres across, ALMA sees larger dust grains that are about a milimetre in size, which are concentrated in the central plane of the disc. This can create the right conditions for the grains to continue to grow and potentially form planets. Indeed, the ALMA data for Oph 163131 shows a gap in the inner disc, which may already be evidence of a planet forming and clearing out the dust around it.

[Image Description: Two images of protoplanetary discs side-by-side. The left image shows a dark horizontal band covering the star, with broad, colourful, conical outflows above and below it, and a narrow jet pointing directly up and down from the star. The right image shows the star within a yellow dusty disc, with scattered dust creating purple lobes above and below the disc. Each is on a black background with several galaxies or stars around it.]

The stellar lifecycle in a nearby spiral

Fri, 20 Feb 2026 10:00:00 +0100

Two powerful instruments of the NASA/ESA/CSA James Webb Space Telescope joined forces to create this scenic galaxy view for today’s Picture of the Month. This spiral galaxy is named NGC 5134, and it’s located 65 million light-years away in the constellation Virgo.

Though 65 million light-years may seem like a huge distance — the light that Webb collected to create this image has been journeying to us from NGC 5134 since soon after Tyrannosaurus rex went extinct — NGC 5134 is fairly close by as far as galaxies go. Because of the galaxy’s relative proximity, Webb can spot incredible details in its tightly wound spiral arms.

Webb’s Mid-InfraRed Instrument (MIRI) collects the mid-infrared light emitted by the warm dust that speckles NGC 5134’s interstellar clouds, tracing clumps and strands of dusty gas. Some of the dust is composed of complex organic molecules called polycyclic aromatic hydrocarbons, which feature interconnected rings of carbon atoms and provide a way for astronomers to study the chemistry happening in interstellar clouds. Webb’s Near-InfraRed Camera (NIRCam) records shorter-wavelength near-infrared light, mostly from the stars and star clusters that dot the galaxy’s spiral arms.

Together, the MIRI and NIRCam data paint a portrait of a galaxy in constant ebb and flow. The gas clouds that billow along NGC 5134’s spiral arms are the sites of star formation, and each star that forms chips away at the galaxy’s supply of star-forming gas. When stars die, they recycle some of that gas back into the galaxy. Massive stars more than about eight times the mass of the Sun do so spectacularly, in cataclysmic supernova explosions that spread stellar material across hundreds of light-years.

Stars like the Sun give back some of their material as well, though more gently; these stars will balloon into bubbling red giants before shrugging off their atmospheres and sending them into space. Whether expelled by explosive supernovae or gentle red giants, this gas can then be incorporated into new stars.

This give and take between gas and stars is the focus of the observing programme (#3707) for which these images were taken. This programme aims to study 55 galaxies in the nearby Universe that are actively forming new stars and have been studied across a broad range of wavelengths. The new Webb data contribute a rich understanding of individual star clusters and star-forming clouds and have already been used to study the life cycle of tiny dust grains, the shape and properties of star-forming clouds, the links between interstellar gas and dust, and the process by which newly formed stars reshape their surrounding environment.

By using Webb to study the infrared light nearby galaxies like NGC 5134 whose stars and gas can be seen in detail, astronomers can apply their knowledge to galaxies too distant to be observed so closely — like those that are scattered in the background of this image, barely more than points of light.

[Image Description: A spiral galaxy, seen tilted diagonally. It has a blue-white, glowing spot at its core. Its oval-shaped disc glows faintly blue throughout with light from its many stars. The disc is filled with waves and strands of bright red dust that swirl around the core. At places there are holes torn in the dust, while elsewhere it forms dense clumps that glow orange. Several tiny, distant galaxies appear across the background.]

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A celebrity cluster in the spotlight

Thu, 22 Jan 2026 10:00:00 +0100

This NASA/ESA/CSA James Webb Space Telescope Picture of the Month brings us a scene from the distant Universe. Pictured here is the galaxy cluster MACS J1149.5+2223, or MACS J1149 for short, which is located about 5 billion light-years away in the constellation Leo.

Galaxy clusters are the largest structures in the Universe that are held together by gravity. Astronomers have confirmed more than 300 galaxies belonging to the MACS J1149 cluster, and they’ve identified several hundred more possible members. At the cluster’s centre, a huddle of ghostly elliptical galaxies rules over the cluster with their immense gravity.

The crushing gravity of this cluster does more than just hold all the galaxies together as they drift through space. As light from galaxies located behind the cluster makes its way toward our telescope, journeying for billions of years, its path through spacetime is bent by the mass of the intervening galaxies.

This phenomenon is called gravitational lensing, and the result is evident in this image of MACS J1149; scattered across the image are subtle and not-so-subtle examples of gravitational lensing, from galaxies that appear to have been stretched into narrow streaks of light to galaxy images that have morphed into strange shapes.

A fantastic example of gravitational lensing can be seen near the centre of the image, just below the brilliant white galaxies at the heart of the cluster. There, the image of a galaxy with distinct spiral arms has been stretched into something resembling a pink jellyfish. This tangled-looking galaxy is home to what was once the most distant single star ever discovered as well as a supernova whose image appeared four times at once.

MACS J1149 has long received the celebrity treatment from leading telescopes, and for good reason. This cluster was one of six investigated through the NASA/ESA Hubble Space Telescope’s Frontier Fields programme. The Frontier Fields galaxy clusters were selected for the strength of their gravitational lensing, and their ability to warp spacetime has granted researchers a glimpse into the early Universe.

Now, Webb is pushing our knowledge horizon to even earlier times, enabling new discoveries like a feasting supermassive black hole less than 600 million years after the Big Bang. Using Webb’s Near-Infrared Spectrograph (NIRSpec), Near-InfraRed Camera (NIRCam), and Near-InfraRed Imager and Slitless Spectrograph (NIRISS), researchers are revealing never-before-seen details of the lives of early galaxies.

The Webb data used to create this image were collected as part of the CAnadian NIRISS Unbiased Cluster Survey (CANUCS) programme #1208 (PI: C. J. Willott). This programme uses Webb’s sensitive instruments to unveil the evolution of low-mass galaxies in the early Universe, revealing their star formation, dust and chemistry. These data will also help researchers study the epoch of reionisation, when the first stars and galaxies lit up the Universe, map the distribution of mass within galaxy clusters, and understand how star formation can slow to a trickle in a cluster environment.

[Image description: A Webb image of many glowing galaxies in deep space, in various shapes and colours, on a black background. There are some large, blue spiral galaxies, some large and pale white elliptical galaxies, and many orange and red, medium-sized galaxies. Even smaller galaxies, down to tiny faint spots, appear in all these colours.]

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Dwarf stars in a glittering sky

Fri, 19 Dec 2025 10:00:00 +0100

The final ESA/Webb Picture of the Month feature for 2025 showcases a festive-looking region filled with glowing clouds of gas and thousands of sparkling stars. This star cluster, known as Westerlund 2, resides in a stellar breeding ground known as Gum 29, located 20,000 light-years away from Earth in the constellation Carina (the Keel).

This image of Westerlund 2 uses data from Webb’s Near-InfraRed Camera (NIRCam) and Mid-InfraRed Instrument (MIRI). The cluster measures between 6 light-years and 13 light-years across, and is host to some of our Milky Way galaxy's hottest, brightest, and most massive stars. It was also the feature of Hubble’s 25th anniversary image in 2015.

This new Webb image captures the bright, brilliant cluster near the top that is packed with young, massive stars whose intense light shapes the entire scene. Below and around them, swirls of orange and red gas form sculpted walls and tangled clouds - material that is being pushed, eroded, and illuminated by the cluster’s powerful radiation. Threaded throughout the view are countless tiny stars just beginning to shine, some still surrounded by the gas and dust from which they formed. The soft blues and pinks are wisps of thinner material drifting between the denser clouds. Scattered across the field are also many bright stars much closer to us, whose sharp, star-shaped patterns are created by Webb’s optics. The result is a vivid portrait of a stellar nursery in action, where intense energy from newborn stars carves dramatic shapes into the surrounding nebula and drives the ongoing cycle of star formation.

These new Webb observations of Westerlund 2 have revealed, for the first time, the full population of brown dwarfs in this extremely massive young star cluster, including objects as small as about 10 times the mass of Jupiter. This data is allowing astronomers to find several hundred stars with discs in various evolutionary states to facilitate our understanding of how discs evolve and how planets form in such massive young clusters. This image was developed using data from Webb’s programme #3523 (M. Guarcello) as part of the Extended Westerlund 1 and 2 Open Clusters Survey (EWOCS).

[Image Description: A cluster of stars inside a large nebula. The clouds of gas and dust are predominantly bright red in colour and wispy, akin to flames. They are clumped in the bottom-left corner. Other clouds, deeper in the cluster behind many of the stars, appear pale pink. The stars are concentrated in the top half of the image and are mostly small, bright white and six-pointed. They cast blue light over the nebula. Other stars with very long spikes surrounding them lie in the foreground.]

A dance of dwarf galaxies

Tue, 02 Dec 2025 10:00:00 +0100

For this new ESA/Webb Picture of the Month, the NASA/ESA/CSA James Webb Space Telescope has spied a pair of dwarf galaxies engaged in a gravitational dance. These two galaxies are named NGC 4490 and NGC 4485, and they’re located about 24 million light-years away in the constellation Canes Venatici (The Hunting Dogs). Aside from the Milky Way’s own dwarf companions (the Large and Small Magellanic Clouds), this is the closest known interacting dwarf-dwarf system where astronomers have directly observed both a gas bridge and resolved stellar populations. Together NGC 4490 and NGC 4485 form the system Arp 269, which is featured in the Atlas of Peculiar Galaxies. At such a close distance (and with Webb’s impressive ability to peer through dusty cosmic clouds) these galaxies allow astronomers to witness up close the kinds of galaxy interactions that were common billions of years ago.

Dwarf galaxies likely share many similarities with young galaxies in the early Universe: they are much less massive than galaxies like the Milky Way, they typically have small amounts of metals (what astronomers call elements heavier than helium), and they contain a lot of gas and relatively few stars. When nearby dwarf galaxies collide, merge, or steal gas from one another, it can tell us how galaxies billions of years ago might have grown and evolved.

The nearby dwarf galaxies NGC 4490 and NGC 4485 form an intriguing pair. Nearly three decades ago, astronomers discovered a wispy bridge of gas connecting the two galaxies, showing that they have interacted in the past. Despite many studies with powerful telescopes like the NASA/ESA Hubble Space Telescope, the history between NGC4490 and NGC 4485 has remained mysterious.

Recently, Webb observed this curious galactic pair as part of the Feedback in Emerging extrAgalactic Star clusTers (FEAST) programme (#1783; PI: A. Adamo). The FEAST programme used Webb’s sensitive infrared eyes to reveal the formation of new stars in different types of nearby galaxies.

This image was developed using data from Webb’s Near-InfraRed Camera (NIRCam) and Mid-InfraRed Instrument (MIRI), as well as a single narrow-band filter from Hubble (657N). It reveals NGC 4490 and NGC 4485 in never-before-seen detail and illuminates the bridge of gas and stars that connects them. NGC 4490 dominates the image as the larger object occupying the left side of the image, while NGC 4485 is the smaller galaxy that hosts the top-right portion of the image. By dissecting these galaxies star by star, researchers were able to map out where young, middle-aged, and old stars reside, and trace the timeline of the galaxies’ interaction.

Roughly 200 million years ago, these galaxies whirled close to one another before waltzing away. The larger galaxy, NGC 4490, ensnared a stream of gas from its companion, and this gas now trails between the galaxies like dancers connected by outstretched arms. Along the newly formed bridge of gas and within the two galaxies, this interaction spurred a burst of new stars. The concentrated areas of bright blue that appear throughout the field indicate highly ionised regions of gas by the recently formed star clusters. Just 30 million years ago, these galaxies burst alight with stars once more, with new clusters coalescing where the gas of the two galaxies mixed together.

By capturing the history of the galactic dancers NGC 4490 and NGC 4485, Webb has revealed new details in how dwarf galaxies interact, giving us a glimpse of how small galaxies near and far grow and evolve.

[Image Description: This Webb image shows two interacting galaxies. NGC 4490 occupies the left side of the image, while NGC 4485 appears as a white glowing hue in the top right of the field. Both galaxies are connected by a bright stream of red stretching from the top left of the image, through the bottom centre, and ending at the right under galaxy NGC 4485. There are regions of bright blue ionised gas visible in concentrated areas of the red stream. The background is black with multiple galaxies in various shapes throughout.]

The Red Spider Nebula, caught by Webb

Tue, 28 Oct 2025 14:00:00 +0100

This new NASA/ESA/CSA James Webb Space Telescope Picture of the Month features a cosmic creepy-crawly called NGC 6537 — the Red Spider Nebula. Using its Near-InfraRed Camera (NIRCam), Webb has revealed never-before-seen details in this picturesque planetary nebula with a rich backdrop of thousands of stars.

Planetary nebulae like the Red Spider Nebula form when ordinary stars like the Sun reach the end of their lives. After ballooning into cool red giants, these stars shed their outer layers and cast them into space, exposing their white-hot cores. Ultraviolet light from the central star ionises the cast-off material, causing it to glow. The planetary nebula phase of a star’s life is as fleeting as it is beautiful, lasting only a few tens of thousands of years.

The central star of the Red Spider Nebula is visible in this image, glowing just brighter than the webs of dusty gas that surround it. The surprising nature of the nebula’s tremendously hot and luminous central star has been revealed by Webb’s NIRCam. In optical-wavelength images, such as from the NASA/ESA Hubble Space Telescope, the star appears faint and blue. But in the NIRCam images, it shows up as red: thanks to its sensitive near-infrared capabilities, Webb has revealed a shroud of hot dust surrounding the central star. This hot dust likely orbits the central star, in a disc structure.

Though only a single star is visible in the Red Spider’s heart, a hidden companion star may lurk there as well. A stellar companion could explain the nebula’s shape, including its characteristic narrow waist and wide outflows. This hourglass shape is seen in other planetary nebulae such as the Butterfly Nebula, which Webb also recently observed.

Webb’s new view of the Red Spider Nebula reveals for the first time the full extent of the nebula’s outstretched lobes, which form the ‘legs’ of the spider. These lobes, shown in blue, are traced by light emitted from H2 molecules, which contain two hydrogen atoms bonded together. Stretching over the entirety of NIRCam’s field of view, these lobes are shown to be closed, bubble-like structures that each extend about 3 light-years. Outflowing gas from the centre of the nebula has inflated these massive bubbles over thousands of years.

Gas is also actively jetting out from the nebula’s centre, as these new Webb observations show. An elongated purple ‘S’ shape centred on the heart of the nebula follows the light from ionised iron atoms. This feature marks where a fast-moving jet has emerged from near the nebula’s central star and collided with material that was previously cast away by the star, sculpting the rippling structure of the nebula seen today.

The observations used to create this image come from Webb GO programme #4571 (PI: J. Kastner) as part of a joint Chandra-JWST observing programme, which aims to understand how bipolar planetary nebulae like the Red Spider Nebula are shaped by the outflows and jets that emerge from the stars at their cores.

[Image Description: A large planetary nebula. The nebula’s central star is hidden by a blotchy pinkish cloud of dust. A strong red light radiates from this area, illuminating the nearby dust. Two large loops extend diagonally away from the centre, formed of thin ridges of molecular gas, here coloured blue. They stretch out to the corners of the view. A huge number of bright, whitish stars cover the background, also easily visible through the thin dust layers.]

Webb brings cosmic lenses into focus

Tue, 30 Sep 2025 10:00:00 +0200

This ESA/Webb Picture of the Month shows eight stunning examples of gravitational lensing. Gravitational lensing, which was first predicted by Einstein, occurs because massive objects like galaxies and clusters of galaxies dramatically warp the fabric of spacetime. When a massive foreground object lines up just so with a background galaxy, the light from the background galaxy bends as it navigates the warped spacetime on its way to our telescopes.

Depending on how perfect the alignment is, the light from the background galaxy can be bent into an arc, a circle (a phenomenon called an ‘Einstein ring’) or even split into multiple images.

Arcs and circles are prevalent in these gravitationally lensed galaxies, which were identified in data from COSMOS-Web, a 255-hour Treasury programme (#1727). COSMOS-Web aims to understand the formation of the most massive galaxies in the Universe, identify galaxies that were present when the first stars and galaxies reionised the Universe’s hydrogen gas, and study the relationship between the mass of a galaxy’s stars and the mass of its galactic halo across cosmic time.

Using these data, researchers carried out the COSMOS-Web Lens Survey, or COWLS, to search for gravitational lenses. The researchers inspected more than 42 000 galaxies by eye and picked out more than 400 promising lensing candidates. This Picture of the Month feature presents a collage of eight of the most spectacular lenses identified by the research team.

This collection of gravitational lenses spans an incredible range of cosmic history. The foreground galaxies give us a glimpse of galactic life when the Universe was 2.7 to 8.9 billion years old. The background galaxies, whose shapes appear visibly distorted, stretch back even further, with one source nicknamed ‘the COSMOS-Web Ring’ (top row, left of centre) letting us peek all the way back to when the Universe was barely more than a billion years old. Several rarities appear in this collection, including an unusual case in which the galaxy acting as the gravitational lens is a flattened disc galaxy rather than an elliptical galaxy (bottom row, second from left).

These images demonstrate Webb’s ability to uncover and reveal never-before-seen details in gravitationally lensed galaxies. Some of the lensed galaxies were previously discovered with the NASA/ESA Hubble Space Telescope and are now seen by Webb in an entirely new light. Others, including those that are especially red due to either dust or distance, were first spotted by Webb. These discoveries open a unique window into the early days of the Universe and enable the study of exquisite details within distant galaxies like individual star clusters and supernovae.

Individual images of the lenses are also available. From left-to-right then top-to-bottom: COSJ100013+023424, COSJ100024+015334, COSJ100018+022138, COSJ100024+021749, COSJ095914+021219, COSJ100025+015245, COSJ095921+020638, and COSJ095593+023319.

[Image Description: A collage of eight Webb images of gravitational lensing are shown. Each of the images show various distorted galaxies in the centre of each frame, including arcs and circular shapes.]

Dusty wisps round a dusty disc

Fri, 29 Aug 2025 10:00:00 +0200

For this new Picture of the Month feature, the NASA/ESA/CSA James Webb Space Telescope has provided a fantastic new view of IRAS 04302+2247, a planet-forming disc located about 525 light-years away in a dark cloud within the Taurus star-forming region. With Webb, researchers can study the properties and growth of dust grains within protoplanetary discs like this one, shedding light on the earliest stages of planet formation.

In stellar nurseries across the galaxy, baby stars are forming in giant clouds of cold gas. As young stars grow, the gas surrounding them collects in narrow, dusty protoplanetary discs. This sets the scene for the formation of planets, and observations of distant protoplanetary discs can help researchers understand what took place roughly 4.5 billion years ago in our own Solar System, when the Sun, Earth, and the other planets formed.

IRAS 04302+2247, or IRAS 04302 for short, is a beautiful example of a protostar - a young star that is still gathering mass from its environment - surrounded by a protoplanetary disc in which baby planets might be forming. Webb is able to measure the disc at 65 billion kilometres across - several times the diameter of our Solar System. From Webb’s vantage point, IRAS 04302’s disc is oriented edge-on, so we see it as a narrow, dark line of dusty gas that blocks the light from the budding protostar at its centre. This dusty gas is fuel for planet formation, providing an environment within which young planets can bulk up and pack on mass.

When seen face-on, protoplanetary discs can have a variety of structures like rings, gaps and spirals. These structures can be signs of baby planets that are burrowing through the dusty disc, or they can point to phenomena unrelated to planets, like gravitational instabilities or regions where dust grains are trapped. The edge-on view of IRAS 04302’s disc shows instead the vertical structure, including how thick the dusty disk is. Dust grains migrate to the midplane of the disc, settle there and form a thin, dense layer that is conducive to planet formation; the thickness of the disc is a measure of how efficient this process has been.

The dense streak of dusty gas that runs vertically across this image cocoons IRAS 04302, blotting out its bright light such that Webb can more easily image the delicate structures around it. As a result, we’re treated to the sight of two gauzy nebulae on either side of the disc. These are reflection nebulae, illuminated by light from the central protostar reflecting off of the nebular material. Given the appearance of the two reflection nebulae, IRAS 04302 has been nicknamed the “Butterfly Star”.

This view of IRAS 04302 features observations from Webb's Near-InfraRed Camera (NIRCam) and its Mid-InfraRed Instrument (MIRI), combined with optical data from the NASA/ESA Hubble Space Telescope. Together, these powerful facilities paint a fascinating multiwavelength portrait of a planetary birthplace. Webb reveals the distribution of tiny dust grains as well as the reflection of near-infrared light off of dusty material that extends a large distance from the disc, while Hubble focuses on the dust lane as well as clumps and streaks surrounding the dust that suggest the star is still collecting mass from its surroundings as well as shooting out jets and outflows.

The Webb observations of IRAS 04302 were taken as part of the Webb GO programme #2562 (PI F. Ménard, K. Stapelfeldt). This programme investigates four protoplanetary discs that are oriented edge-on from our point of view, aiming to understand how dust evolves within these discs. The growth of dust grains in protoplanetary discs is believed to be an important step toward planet formation.

[Image description: A wide-field image of IRAS 16594-4656 taken by the James Webb Space Telescope. The nebula’s bright core is split by a narrow dark band, with expansive rainbow lobes of light and colour radiating outward. Numerous background galaxies and stars are visible across the field.]

A fresh look at a classic deep field

Fri, 01 Aug 2025 10:00:00 +0200

This image from the NASA/ESA/CSA James Webb Space Telescope revisits one of the most iconic regions of the sky, the Hubble Ultra Deep Field, through the eyes of two of Webb’s instruments. The result is a detailed view that reveals thousands of distant galaxies, some dating back to the earliest periods of cosmic history.

The field shown here, known as the MIRI Deep Imaging Survey (MIDIS) region, was observed with the three shortest-wavelength filters of Webb’s Mid-Infrared Instrument (MIRI) for nearly 100 hours in total. This included Webb's longest observation of an extragalactic field in one filter so far, producing one of the deepest views ever obtained of the Universe. Combined with data from Webb’s Near-Infrared Camera (NIRCam), this image allows astronomers to explore how galaxies formed and evolved over billions of years.

These deep observations have revealed more than 2500 sources in this tiny patch of sky. Among them are hundreds of extremely red galaxies — some of which are likely massive, dust-obscured systems or evolved galaxies with mature stars that formed early in the Universe’s history. Thanks to Webb’s sharp resolution, even at mid-infrared wavelengths, researchers can resolve the structures of many of these galaxies and study how their light is distributed, shedding light on their growth and evolution.

In this image, the colours that have been assigned to different kinds of infrared light highlight the fine distinctions astronomers can make with this deep data. Orange and red represent the longest mid-infrared wavelengths. The galaxies in these colours have extra features — such as high concentrations of dust, copious star formation, or an active galactic nucleus (AGN) at their centre — which emit more of this farther infrared light. Small, greenish-white galaxies are particularly distant, with high redshift. This shifts their light spectrum into the peak mid-infrared wavelengths of the data, which are depicted in white and green. Most of the galaxies in this image lack any such mid-infrared boosting features, leaving them most bright at shorter near-infrared wavelengths, which are depicted with blue and cyan colours.

By returning to this legacy field first made famous by the NASA/ESA Hubble Space Telescope, Webb is continuing and expanding the deep field tradition — revealing new details, uncovering previously hidden galaxies, and offering fresh insights into the formation of the first cosmic structures.

The MIRI observations were taken as part of the Webb programmes #1283 and #6511 (PI: G. Östlin).

[Image Description: An area of deep space with thousands of galaxies in various shapes and sizes on a black background. Most are circles or ovals, with a few spirals. More distant galaxies are smaller, down to being mere dots, while closer galaxies are larger and some appear to be glowing. Red and orange galaxies contain more dust or more stellar activity.]

A starburst shines in infrared

Mon, 30 Jun 2025 10:00:00 +0200

Featured in this NASA/ESA/CSA James Webb Space Telescope Picture of the Month is a nearby galaxy that outshines the Milky Way. This galaxy, called Messier 82 (M82) or the Cigar Galaxy, is situated just 12 million light-years away in the constellation Ursa Major.

Despite being smaller than the Milky Way, M82 is five times as luminous as our home galaxy and forms stars ten times faster. M82 is classified as a starburst galaxy because it is forming new stars at a rate much faster than expected for a galaxy of its mass, especially at its centre. In visible-light images of M82, the central hotbed of activity is obscured by a network of thick and dusty clouds. Webb’s Near-InfraRed Camera (NIRCam) has drawn back these clouds, revealing the full brilliance of the galactic centre.

What caused M82’s burst of star formation? The answer likely lies with its neighbour, the larger spiral galaxy M81. Researchers suspect that the two galaxies have interacted gravitationally, sending gas pouring into M82’s centre millions of years ago. The influx of gas provided the raw material for new stars to form — and form they did! M82 is home to more than 100 super star clusters, some of which are still in the process of forming and are blanketed with dense, dusty gas. Super star clusters are more massive and luminous than typical star clusters; these each contain hundreds of thousands of stars.

A previous Webb NIRCam image of M82 was released in 2024. The earlier image focused on the very core of the galaxy, where individual clusters of young stars stand out against the clumps and tendrils of gas. This new image takes a broader view of M82’s brilliant centre, capturing the light of billions of stars as well as the glow of organic molecules called polycyclic aromatic hydrocarbons, or PAHs.

Researchers used the new Webb data to identify plumes traced by the emission from PAH molecules. Each plume is only about 160 light-years wide, and the Webb images show that these plumes are made up of multiple individual clouds that are 16–49 light-years across — an incredible level of detail enabled by Webb’s sensitive instruments. These clouds appear to have been caught up in the galaxy’s powerful outflowing winds and whisked away from the galactic disc.

Ultimately, this phenomenon points back to the galaxy’s remarkable abundance of massive star clusters: as these massive clusters form, their newborn stars sear the surrounding gas with high-energy radiation and particles, launching the outflowing wind that is traced by this NIRCam image.

[Image Description: An image of the central part of galaxy M82. The galaxy’s disc extends from the top to the bottom of the image, emitting a blue-white glow. Gas erupts from the brightly shining centre, forming an hourglass-shaped plume of red and orange dust clouds to the left and right. Ridges and cavities in the gas are visible in great detail. Many distant galaxies can be seen in the background, as well as tiny pinprick stars in M82.]

A glimpse of the distant past

Tue, 27 May 2025 10:00:00 +0200

The eye is first drawn, in this new NASA/ESA/CSA James Webb Space Telescope Picture of the Month, to the central mega-monster that is galaxy cluster Abell S1063. This behemoth collection of galaxies, lying 4.5 billion light-years from Earth in the constellation Grus (the Crane), dominates the scene. Looking more closely, this dense collection of heavy galaxies is surrounded by glowing streaks of light, and these warped arcs are the true object of scientists’ interest: faint galaxies from the Universe’s distant past.

Abell S1063 was previously observed by the NASA/ESA Hubble Space Telescope’s Frontier Fields programme. It is a strong gravitational lens: the galaxy cluster is so massive that the light of distant galaxies aligned behind it is bent around it, creating the warped arcs that we see here. Like a glass lens, it focuses the light from these faraway galaxies. The resulting images, albeit distorted, are both bright and magnified — enough to be observed and studied. This was the aim of Hubble’s observations, using the galaxy cluster as a magnifying glass to investigate the early Universe.

The new imagery from Webb’s Near-Infrared Camera (NIRCam) takes this quest even further back in time. This image showcases an incredible forest of lensing arcs around Abell S1063, which reveal distorted background galaxies at a range of cosmic distances, along with a multitude of faint galaxies and previously unseen features.

This image is what’s known as a deep field — a long exposure of a single area of the sky, collecting as much light as possible to draw out the most faint and distant galaxies that don’t appear in ordinary images. With 9 separate snapshots of different near-infrared wavelengths of light, totalling around 120 hours of observing time and aided by the magnifying effect of gravitational lensing, this is Webb’s deepest gaze on a single target to date. Focusing such observing power on a massive gravitational lens, like Abell S1063, therefore has the potential to reveal some of the very first galaxies formed in the early Universe.

The observing programme that produced this data, GLIMPSE (#3293, PIs: H. Atek & J. Chisholm), aims to probe the period known as Cosmic Dawn, when the Universe was only a few million years old. Studying the galaxies revealed by gravitational lensing has the potential to develop our understanding of the emergence of the first galaxies. Analysis of this NIRCam data by the GLIMPSE team has already produced candidates for galaxies that existed as early as 200 million years after the Big Bang, and hints of the elusive first population of stars in the Universe.

[Image Description: A field of galaxies in space, dominated by an enormous, bright-white elliptical galaxy that is the core of a massive galaxy cluster. Many other elliptical galaxies can be seen around it. Also around it are short, curved, glowing red lines, which are images of distant background galaxies magnified and warped by gravitational lensing. A couple of foreground stars appear large and bright with long spikes around them.]

Infrared, optical, and X-ray views of a galaxy group

Tue, 29 Apr 2025 10:00:00 +0200

Spying a spiral through a cosmic lens

Thu, 27 Mar 2025 10:00:00 +0100

This new NASA/ESA/CSA James Webb Space Telescope Picture of the Month features a rare cosmic phenomenon called an Einstein ring. What at first appears to be a single, strangely shaped galaxy is actually two galaxies that are separated by a large distance. The closer foreground galaxy sits at the center of the image, while the more distant background galaxy appears to be wrapped around the closer galaxy, forming a ring.

Einstein rings occur when light from a very distant object is bent (or ‘lensed’) about a massive intermediate (or ‘lensing’) object. This is possible because spacetime, the fabric of the Universe itself, is bent by mass, and therefore light travelling through space and time is bent as well. This effect is much too subtle to be observed on a local level, but it sometimes becomes clearly observable when dealing with curvatures of light on enormous, astronomical scales, such as when the light from one galaxy is bent around another galaxy or galaxy cluster.

When the lensed object and the lensing object line up just so, the result is the distinctive Einstein ring shape, which appears as a full circle (as seen here) or a partial circle of light around the lensing object, depending on the precision of the alignment. Objects like these are the ideal laboratory in which to research galaxies too faint and distant to otherwise see.

The lensing galaxy at the center of this Einstein ring is an elliptical galaxy, as can be seen from the galaxy’s bright core and smooth, featureless body. This galaxy belongs to a galaxy cluster named SMACSJ0028.2-7537. The lensed galaxy wrapped around the elliptical galaxy is a spiral galaxy. Even though its image has been warped as its light travelled around the galaxy in its path, individual star clusters and gas structures are clearly visible.

The Webb data used in this image were taken as part of the Strong Lensing and Cluster Evolution (SLICE) survey (programme 5594), which is led by Guillaume Mahler at University of Liège in Belgium, and consists of a team of international astronomers. This survey aims to trace 8 billion years of galaxy cluster evolution by targeting 182 galaxy clusters with Webb’s Near-InfraRed Camera instrument. This image also incorporates data from two of the NASA/ESA Hubble Space Telescope’s instruments, the Wide Field Camera 3 and the Advanced Camera for Surveys.

[Image Description: In the centre is an elliptical galaxy, seen as an oval-shaped glow around a small bright core. Around this is wrapped a broad band of light, appearing like a spiral galaxy stretched and warped into a ring, with bright blue lines drawn through it where the spiral arms have been stretched into circles. A few distant objects are visible around the ring on a black background.]

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Webb visits a star-forming spiral

Fri, 28 Feb 2025 10:00:00 +0100

The target of today’s NASA/ESA/CSA James Webb Space Telescope Picture of the Month is the spiral galaxy NGC 2283. This galaxy resides roughly 45 million light-years away in the constellation Canis Major. Classified as a barred spiral galaxy, NGC 2283’s central bar of stars is encircled by loosely wound spiral arms.

This new image shows NGC 2283 through the eyes of Webb’s Near-InfraRed Camera (NIRCam) and Mid-InfraRed Instrument (MIRI). Webb gazed at NGC 2283 for a combined 17 minutes to collect the data for this image, which is constructed from six snapshots taken with different near- and mid-infrared filters. These filters reveal the emission from NGC 2283’s sparkling stellar population, as well as the light from clouds of hydrogen gas that have been heated by young stars. Sooty molecules called polycyclic aromatic hydrocarbons, of great interest to astronomers, emit light that’s mapped by two of the filters used here. The large, bright stars with prominent diffraction spikes on display in this image are inhabitants of our own galaxy, which lie between us and NGC 2283.

The new Webb images of NGC 2283 were collected as part of an observing programme (#3707) dedicated to understanding the connections between stars, gas and dust in nearby star-forming galaxies. NGC 2283 is just one of the 55 galaxies in the local Universe examined by Webb for this programme. All of the galaxies surveyed in this programme are massive star-forming galaxies close enough for individual star clusters and gas clouds to be visible.

These star clusters and gas clouds are on full display, outlining the galaxy’s graceful spiral arms. The dense knots of gas illuminated by young stars are evidence for active star formation that is turning cold hydrogen gas into blazing stars in NGC 2283.

Galaxies with active star formation often play host to spectacular stellar explosions called core-collapse supernovae. Just over two years ago, on 28 January 2023, a supernova named SN 2023AXU was discovered in NGC 2283. SN 2023AXU is what’s known as a Type II supernova — the collapse of the core of a star at least eight times as massive as the Sun and subsequent rebounding and explosion of the star’s outer layers.

While the process of star formation converts gas into new stars, supernovae complete the cycle. The explosion of a supernova can fling gas across hundreds of light-years, enriching the star-forming clouds of the interstellar medium with elements like oxygen and sodium. Over time, the supernova-enriched gas is incorporated into new generations of stars, continuing the life cycle of gas and stars in galaxies across the Universe.

[Image Description: A spiral galaxy seen close up and almost face on. It is filled with puffy, patchy clouds of hot gas and dust. Red, orange and yellow colours indicate light emitted by different particles. The brightest colours are in the centre and along the two spiral arms, which wind out from the centre. Star clusters hide in the gas along the arms. A few large, bright white stars are prominent in the foreground, near to us.]

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Webb investigates a dusty and dynamic disc

Tue, 04 Feb 2025 10:00:00 +0100

This new NASA/ESA/CSA James Webb Space Telescope Picture of the Month presents HH 30 in unprecedented resolution. This target is an edge-on protoplanetary disc that is surrounded by jets and a disc wind, and is located in the dark cloud LDN 1551 in the Taurus Molecular Cloud.

Herbig-Haro objects are small nebulae found in star formation regions, marking the locations where gas outflowing from young stars is heated into luminescence by shockwaves. HH 30 is an example of where this outflowing gas takes the form of a narrow jet. The source star is located on one end of the jet, hidden behind an edge-on protoplanetary disc that the star is illuminating.

HH 30 is of particular interest to astronomers. In fact, the HH 30 disc is considered the prototype of an edge-on disc, thanks to its early discovery with the NASA/ESA Hubble Space Telescope. Discs seen from this view are a unique laboratory to study the settling and drift of dust grains.

An international team of astronomers have used Webb to investigate the target in unprecedented detail. By combining Webb’s observations with those from the Hubble Space Telescope and the Atacama Large Millimeter/submillimeter Array (ALMA), the team was able to study the multiwavelength disc appearance of the system.

The long-wavelength data from ALMA trace the location of millimetre-sized dust grains, which are found in a narrow region in the central plane of the disc. The shorter-wavelength infrared data from Webb reveal the distribution of smaller dust grains. These grains are only one millionth of a metre across — about the size of a single bacterium. While the large dust grains are concentrated in the densest parts of the disc, the small grains are much more widespread.

These Webb observations were taken as part of the Webb GO programme #2562 (PI F. Ménard, K. Stapelfeldt), which aims to understand how dust evolves in edge-on discs like HH 30. Combined with the keen radio-wavelength eyes of ALMA, these observations show that large dust grains must migrate within the disc and settle in a thin layer. The creation of a narrow, dense layer of dust is an important stage in the process of planet formation. In this dense region, dust grains clump together to form pebbles and eventually planets themselves.

In addition to the behaviour of dust grains, the Webb, Hubble, and ALMA images reveal several distinct structures that are nested within one another. Emerging at a 90-degree angle from the narrow central disc is a high-velocity jet of gas. The narrow jet is surrounded by a wider, cone-shaped outflow. Enclosing the conical outflow is a wide nebula that reflects the light from the young star that is embedded within the disc. Together, these data reveal HH 30 to be a dynamic place, where tiny dust grains and massive jets alike play a role in the formation of new planets.

The annotated verision of this image can be seen here.

[Image Description: A close-in image of a protoplanetary disc around a newly formed star. Many different wavelengths of light are combined and represented by separate and various colours. A dark line across the centre is the disc, corresponding to the densest parts of the disc, made of opaque dust: the star is hidden in here and creates a strong glow in the centre. A band going straight up is a jet, while other outflows above and below the disc, and a tail coming off to one side.]

Close look at a local galaxy

Wed, 18 Dec 2024 10:00:00 +0100

The galaxy filling the frame in this NASA/ESA/CSA James Webb Space Telescope Picture of the Month is NGC 2566, a spiral galaxy located in the constellation Puppis. The image combines observations from two of Webb’s instruments, the Near-InfraRed Camera (NIRCam) and Mid-InfraRed Instrument (MIRI), to show off NGC 2566’s well-defined spiral arms, long central bar and delicate tracery of gas, dust and stars.

At 76 million light-years away, NGC 2566 is considered a nearby galaxy, making it an excellent target for studying fine details like star clusters and gas clouds. The new Webb images of NGC 2566 were collected as part of an observing programme (#3707) dedicated to understanding the connections between stars, gas and dust in nearby star-forming galaxies. NGC 2566 is just one of the 55 galaxies in the local Universe examined by Webb for this programme.

The mid-infrared wavelengths captured by MIRI highlight NGC 2566’s warm interstellar dust, including complex, sooty molecules called polycyclic aromatic hydrocarbons. The near-infrared NIRCam data give a detailed view of the galaxy’s stars, even those that are deeply embedded within clouds of gas. The NIRCam data also capture some of the light from the hydrocarbon molecules.

To gain a full understanding of the star-formation process in nearby galaxies, astronomers will combine Webb data with observations from other telescopes. At the long-wavelength end of the electromagnetic spectrum, the 66 radio dishes of the Atacama Large Millimeter/submillimeter Array (ALMA) provide a detailed view of the cold, turbulent clouds where stars are born. The NASA/ESA Hubble Space Telescope has also cast its gaze on NGC 2566, and a new Hubble image of this galaxy was released earlier this week. The Hubble data will help researchers take a census of the stars in nearby galaxies, especially the young stars that are bright at the ultraviolet and visible wavelengths to which Hubble is sensitive. Together, the Webb, Hubble and ALMA data provide a rich view of the cold gas, warm dust and brilliant stars in NGC 2566.

The Webb data are part of a Treasury programme, which means that the data may help answer multiple important questions about our Universe. Treasury data are available for use by scientists and the public without a waiting period, amplifying the scientific impact and allowing exploration to begin immediately.

[Image Description: An oval-shaped spiral galaxy, seen close-up. Its core is a compact, pale spot that glows brightly, filling the disc with bluish light. Faint strands of pale reddish dust swirl out from the core to the far sides of the disc. They each join up with an arm of thick, cloudy, red dust with brighter orange patches, that follows the edge of the disc around to the opposite end and a little off the galaxy.]

Tracing spiral arms in infrared

Wed, 27 Nov 2024 10:00:00 +0100

Featured in this NASA/ESA/CSA James Webb Space Telescope Picture of the Month is the spiral galaxy NGC 2090, located in the constellation Columba. This combination of data from Webb’s MIRI and NIRCam instruments shows the galaxy’s two winding spiral arms and the swirling gas and dust of its disc in magnificent and unique detail.

This was one of the group of galaxies studied early on by the NASA/ESA Hubble Space Telescope, observing Cepheid variable stars in it as part of refining the measurement of the Hubble constant. The Cepheid-based measurement from that study in 1998 put NGC 2090 as 37 million light-years away; the newest measurements have NGC 2090 slightly farther away, at 40 million light-years. Hubble is to this day surveying galaxies in visible and ultraviolet light; alongside this Webb image a new Hubble image of NGC 2090 has also been published this week, which you can find here.

Before and since that project, NGC 2090 has been well studied as a very prominent nearby example of star formation. It has been described as a flocculent spiral, meaning a spiral galaxy with a patchy, dusty disc and arms that are flaky or not visible at all. Visible-light images show this well, but the near-infrared data from NIRCam used in this image reveal the spiral arms with remarkable clarity. NIRCam also picks up bright light from stars, displayed by the blue colours most visible in the centre. Meanwhile, mid-infrared light emitted mainly by the important carbon-based compounds known as polycyclic aromatic hydrocarbons along the many strands of gas and dust is captured by MIRI and shown here in red.

These data on NGC 2090 were collected as part of an observing programme (#3707) taking a census of nearby massive, star-forming galaxies much like it. These galaxies are at just the right distance, with the right size and level of activity, that Webb’s instruments can capture a comprehensive picture of the star-forming activity, including the tightly-bound clusters that stars often form in, and the clouds of gas in the galaxy in which stars can be born. The rich collection of detailed images like this one will be of value to astronomers studying this area for years to come.

[Image Description: A spiral galaxy with a wide, oval-shaped disc. It has a shining spot at the centre from which two curving, pale red spiral arms emerge, wrapping once each around the galaxy. They’re surrounded by a whirl of bright threads and patches of dust, with spots of star formation scattered throughout. The glow of the disc fades smoothly into the background where some patches of dust can be seen, as well as foreground stars.]

Catching the edge of the Phantom Galaxy

Tue, 29 Oct 2024 10:00:00 +0100

In August 2022, to mark the launch of the Picture of the Month series, ESA/Webb published a stunning image of the Phantom Galaxy (also known as M74 and NGC 628). Now, this series is revisiting the target to feature new data on this iconic spiral galaxy.

M74 resides around 32 million light-years away from Earth in the constellation Pisces, and lies almost face-on to Earth. This, coupled with its well-defined spiral arms, makes it a favourite target for astronomers studying the origin and structure of galactic spirals.

This image features data from two of Webb’s instruments: MIRI (Mid-InfraRed Instrument) and NIRCam (Near-InfraRed Camera). Observations in the infrared reveal the galaxy’s creeping tendrils of gas, dust and stars. In this image the dark red regions trace the filamentary warm dust permeating the galaxy. The red regions show the reprocessed light from complex molecules forming on dust grains, while orange and yellow colours reveal the regions of gas ionised by the recently formed star clusters. Stellar feedback has a dramatic effect on the medium within the galaxy and creates a complex network of bright knots as well as cavernous black bubbles. The lack of gas in the nuclear region of this galaxy also provides an unobscured view of the nuclear star cluster at the galaxy's centre. M74 is a particular class of spiral galaxy known as a ‘grand design spiral’, meaning that its spiral arms are prominent and well-defined, unlike the patchy and ragged structure seen in some spiral galaxies.

M74 was observed by Webb as part of a series of observations collectively entitled Feedback in Emerging extrAgalactic Star clusTers, or FEAST (PI: A. Adamo). Many other targets of the FEAST programme, including NGC 4449, M51, and M83, were the subjects of previous ESA/Webb Picture of the Month images in 2023 and 2024. The FEAST observations were designed to shed light on the interplay between stellar feedback and star formation in environments outside the Milky Way galaxy. Stellar feedback is the term used to describe the outpouring of energy from stars into the environments which form them, and is a process that contributes significantly to determining the rates at which stars form. Understanding stellar feedback is vital for building accurate universal models of star formation.

The new Webb data obtained by the FEAST team has allowed scientists to look at the stellar nurseries in galaxies that are many light years away. Astronomers are learning how other galaxies are forming stars and how stars actively participate to model the galaxy interstellar medium. They have found that newly born stars slowly carve they gas and dust nurseries modifying the morphological appearance and essentially destructing them, as Webb has shown that this evolution is connected with star clusters. Furthermore, the team has concluded from their studies that the spiral arms captured by the extended coverage of the FEAST programme are the places where stars are forming more actively in the galaxy. The brighter and larger complexes of stellar nurseries are in the spiral arms fully captured by the new Webb data. The telescope is now revealing the map of hydrogen emission lines in the near-infrared. These lines are less affected than the dusts and reveals the places where new massive stars have just formed.

[Image Description: A large spiral galaxy takes up the entirety of the image. The core is mostly bright white, but there are also swirling, detailed structures that resemble water circling a drain. There is small white and pale blue light that emanates from stars and dust at the core’s centre, but it is tightly limited to the core. The rings feature colours of deep red and orange and highlight filaments of dust around cavernous black bubbles.]

The exotic stellar population of Westerlund 1

Fri, 04 Oct 2024 10:00:00 +0200

The open cluster Westerlund 1, showcased in this new Webb Picture of the Month, is located roughly 12 000 light-years away in the southern constellation Ara (the Altar) where it resides behind a huge interstellar cloud of gas and dust. It was discovered in 1961 from Australia by Swedish astronomer Bengt Westerlund. Westerlund 1 is an incomparable natural laboratory for the study of extreme stellar physics, helping astronomers to find out how the most massive stars in our Galaxy live and die.

The unique draw of Westerlund 1 is its large, dense, and diverse population of massive stars, which has no counterpart in other known Milky Way galaxy clusters in terms of the number of stars and the richness of spectral types and evolutionary phases. All stars identified in this cluster are evolved and very massive, spanning the full range of stellar classifications including Wolf-Rayet stars, OB supergiants, yellow hypergiants (nearly as bright as a million Suns) and luminous blue variables. Because such stars have a rather short life, Westerlund 1 is very young, astronomically speaking. Astronomers estimate the cluster’s age to be somewhere between 3.5 and 5 million years (its exact age is still a matter of debate), making it a newborn cluster in our galaxy. In the future, it is believed that it will likely evolve from an open cluster into a globular cluster. These are roughly spherical, tightly packed collections of old stars bound together by gravity.

Currently, only a handful of stars form in our galaxy each year, but in the past the situation was different. The Milky Way galaxy used to produce many more stars, likely hitting its peak of churning out dozens or hundreds of stars per year about 10 billion years ago and then gradually declining ever since. Astronomers think that most of this star formation took place in massive clusters of stars, known as “super star clusters”. These are young clusters of stars that contain more than 10,000 times the mass of the Sun, packed into an unbelievably small volume. They represent the most extreme environments in which stars and planets can form. Only a few super star clusters still exist in our galaxy — of which Westerlund 1 is one — but they offer important clues about this earlier era when most of our galaxy’s stars formed.

Westerlund 1 is an impressive example of a super star cluster: it contains hundreds of very massive stars, some shining with a brilliance of almost one million Suns and others two thousand times larger than the Sun (as large as the orbit of Saturn). Indeed, if the Solar System was located at the heart of this remarkable cluster, our sky would be full of hundreds of stars as bright as the full Moon. It appears to be the most massive compact young cluster yet identified in the Milky Way galaxy: astronomers believe that this extreme cluster contains between 50 000 and 100 000 times the mass of the Sun, yet all of its stars are located within a region less than six light-years across. Even so, it is the biggest of these remaining super star clusters in the Milky Way galaxy, and the closest super star cluster to Earth. These qualities make Westerlund 1 an excellent target for studying the impact of a super star cluster’s environment on the formation process of stars and planets, as well as the evolution of stars over a broad range of masses.

The huge population of massive stars in Westerlund 1 suggests that it will have a very significant impact on its surroundings. The cluster contains so many massive stars that in a time span of less than 40 million years, it will be the site of more than 1 500 supernovae. This super star cluster now provides astronomers with a unique perspective towards one of the most extreme environments in the Universe. Westerlund 1 will certainly provide new opportunities in the long-standing quest for more and finer details about how stars, and especially massive stars, form.

This image was captured as part of the The Extended Westerlund 1 and 2 Open Clusters Survey (EWOCS) with Webb’s Near-InfraRed Camera (NIRCam). This survey is a dedicated Webb program (GO 1905, PI: M. G. Guarcello) that aims to study star and planet formation and stellar evolution in starburst regions in Westerlund 1 and Westerlund 2, two of the closest super star clusters to the Sun.

With its unparalleled performance in the infrared, Webb offers astronomers the opportunity to unveil the population of low-mass stars in local super star clusters for the first time, and to study the environments around these clusters’ most massive stars. Webb observations of the massive stars in super star clusters can shed light on how feedback (stellar winds, supernovae and other ejected material) from these stars impacts their surrounding environments and the overall star formation process within their parental clouds.

[Image Description: A dense cluster of bright stars, each with six large and two small diffraction spikes, due to the telescope’s optics. They have a variety of sizes depending on their brightness and distance from us in the cluster, and different colours reflecting different types of star. Patches of billowing red gas can be seen in and around the cluster, lit up by the stars. Small stars in the cluster blend into a background of distant stars and galaxies on black.]

Peeking into Perseus

Tue, 27 Aug 2024 10:00:00 +0200

This stunning new mosaic of images from the NASA/ESA/CSA James Webb Space Telescope showcases the nearby star-forming cluster, NGC 1333. The nebula is in the Perseus molecular cloud, and located approximately 960 light-years away.

Webb’s superb sensitivity allows astronomers to investigate young objects with extremely low masses. Some of the faintest ‘stars’ in the picture are in fact newly born free-floating brown dwarfs with masses comparable to those of giant planets.

The same cluster was featured as the 33rd anniversary image of the NASA/ESA Hubble Space Telescope in April of 2023. Hubble’s image just scratched the surface of this region, because clouds of dust obscure much of the star formation process. Observing with a larger aperture and in the infrared part of the spectrum, Webb is capable of peering through the dusty veil to reveal newborn stars, brown dwarfs and planetary mass objects.

The centre of the image presents a deep peek into the heart of the NGC 1333 cloud. Across the image we see large patches of orange, which represent gas glowing in the infrared. These so-called Herbig-Haro objects form when ionised material ejected from young stars collides with the surrounding cloud. They are hallmarks of a very active site of star formation.

Many of the young stars in this image are surrounded by discs of gas and dust, which may eventually produce planetary systems. On the right hand side of the image, we can glimpse the shadow of one of these discs oriented edge-on — two dark cones emanating from opposite sides, seen against a bright background.

Similarly to the young stars in this mosaic, our own Sun and planets formed inside a dusty molecular cloud, 4.6 billion years ago. Our Sun didn’t form in isolation but as part of a cluster, which was perhaps even more massive than NGC 1333. The cluster in the mosaic, only 1–3 million years old, presents us with an opportunity to study stars like our Sun, as well as brown dwarfs and free-floating planets, in their nascent stages.

The images were captured as part of the Webb observation programme 1202 (PI: A. Scholz) to survey a large portion of NGC 1333. These data constitute the first deep spectroscopic survey of the young cluster, and have identified brown dwarfs down to planetary masses using the observatory’s Near-InfraRed Imager and Slitless Spectrograph (NIRISS). The first results from this survey have been accepted for publication in the Astronomical Journal.

[Image Description: A nebula made up of cloudy gas and dust in the form of soft and wispy clouds and, in the centre, thin and highly detailed layers pressed close together. Large, bright stars surrounded by six long points of light are dotted over the image, as well as some small, point-like stars embedded in the clouds. The clouds are lit up in blue close to the stars; orange colours show clouds that glow in infrared light.]

The hidden intricacies of Messier 106

Fri, 09 Aug 2024 10:00:00 +0200

Featured in this new image from the NASA/ESA/CSA James Webb Space Telescope is Messier 106, also known as NGC 4258. This is a nearby spiral galaxy that resides roughly 23 million light-years away in the constellation Canes Venatici, practically a neighbour by cosmic standards. Messier 106 is one of the brightest and nearest spiral galaxies to our own and two supernovae have been observed in this galaxy in 1981 and 2014.

At its heart, as in most spiral galaxies, is a supermassive black hole, but this one is particularly active. Unlike the black hole at the centre of the Milky Way, which pulls in wisps of gas only occasionally, Messier 106’s black hole is actively gobbling up material. As the gas spirals towards the black hole, it heats up and emits powerful radiation.

This image was captured with Webb’s Near-InfraRed Camera (NIRCam). This observation was taken as part of a dedicated programme to study the galaxy’s Active Galactic Nucleus, the galaxy’s bright central region that is dominated by the light emitted by dust and gas as it falls into the black hole. The blue regions in this image reflect stellar distribution throughout the central region of the galaxy. The orange regions indicate warmer dust and the stronger red hues represent colder dust. The teal, green and yellow tones near the centre of the image depict varying gas distributions throughout the region.

The galaxy has a remarkable feature – it is known to have two “anomalous” extra arms visible in radio and X-ray wavelengths, rather than in the visible. Unlike the normal arms, these are composed of hot gas instead of stars. Astronomers believe these extra arms result from the black hole’s activity, a feedback effect seen in other galaxies as well. They are likely caused by outflowing material produced by the violent churning of gas around the black hole, creating a phenomenon analogous to a wave crashing up out of the ocean when it hits a rock near the shore.

Despite carrying his name, Messier 106 was neither discovered nor catalogued by the renowned 18th century astronomer Charles Messier. Discovered by his assistant, Pierre Méchain, the galaxy was never added to the catalogue in his lifetime. Along with six other objects discovered but not logged by the pair, Messier 106 was posthumously added to the Messier catalogue in the 20th century.

[Image Description: The central region of a spiral galaxy. Its core is a small bright point radiating bright, bluish-white light over the scene. The white light is diffuse and many point-like stars in the galaxy (and even background galaxies) can be seen through it. The galaxy’s arms can be seen as broad, swirling streaks of glowing gas and dust, coloured red and orange. Two additional arms are revealed in green.]

Jewelled ring

Fri, 05 Jul 2024 10:00:00 +0200

This new ESA/Webb Picture of the Month features the gravitational lensing of the quasar known as RX J1131-1231, located roughly 6 billion light-years from Earth in the constellation Crater. It is considered one of the best lensed quasars discovered to date, as the foreground galaxy smears the image of the background quasar into a bright arc and creates four images of the object.

Gravitational lensing, first predicted by Einstein, offers a rare opportunity to study regions close to the black hole in distant quasars, by acting as a natural telescope and magnifying the light from these sources. All matter in the Universe warps the space around itself, with larger masses producing a more pronounced effect. Around very massive objects, such as galaxies, light that passes close by follows this warped space, appearing to bend away from its original path by a clearly visible amount. One of the consequential effects of gravitational lensing is that it can magnify distant astronomical objects, letting astronomers study objects that would otherwise be too faint or far away.

Measurements of the X-ray emission from quasars can provide an indication of how fast the central black hole is spinning, which can provide researchers important clues about how black holes grow over time. For example, if a black hole grows primarily from collisions and mergers between galaxies, it should accumulate material in a stable disc, and the steady supply of new material from the disc should lead to a rapidly spinning black hole. On the other hand, if the black hole grew through many small accretion episodes, it would accumulate material from random directions. Observations have indicated that the black hole in this particular quasar is spinning at over half the speed of light, which suggests that this black hole has grown via mergers, rather than pulling material in from different directions.

This image was captured with Webb’s MIRI (Mid-Infrared Instrument) as part of an observation programme to study dark matter. Dark matter is an invisible form of matter that accounts for most of the Universe's mass. Webb’s observations of quasars are allowing astronomers to probe the nature of dark matter at smaller scales than ever before.

[Image Description: A small image of a galaxy distorted by gravitational lensing into a dim ring. At the top of the ring are three very bright spots with diffraction spikes coming off them, right next to each other: these are copies of a single quasar in the lensed galaxy, duplicated by the gravitational lens. In the centre of the ring, the elliptical galaxy doing the lensing appears as a small blue dot. The background is black and empty.]

Fireworks of stellar starbursts

Wed, 29 May 2024 14:00:00 +0200

Featured in this new image from the NASA/ESA/CSA James Webb Space Telescope is the dwarf galaxy NGC 4449. This galaxy, also known as Caldwell 21, resides roughly 12.5 million light-years away in the constellation Canes Venatici. It is part of the M94 galaxy group, which lies close to the Local Group that hosts our Milky Way.

NGC 4449 has been forming stars for several billion years, but it is currently experiencing a period of star formation at a much higher rate than in the past. Such unusually explosive and intense star formation activity is called a starburst and for that reason NGC 4449 is known as a starburst galaxy. In fact, at the current rate of star formation, the gas supply that feeds the production of stars would only last for another billion years or so. Starbursts usually occur in the central regions of galaxies, but NGC 4449 displays more widespread star formation activity, and the very youngest stars are observed both in the nucleus and in streams surrounding the galaxy. It's likely that the current widespread starburst was triggered by interaction or merging with a smaller companion; indeed, astronomers think NGC 4449's star formation has been influenced by interactions with several of its neighbours.

NGC 4449 resembles primordial star-forming galaxies which grew by merging with and accreting smaller stellar systems. Since NGC 4449 is close enough to be observed in great detail, it is the ideal laboratory for astronomers to study what may have occurred during galaxy formation and evolution in the early Universe.

This new image makes use of data from two of Webb’s instruments: MIRI (Mid-InfraRed Instrument) and NIRCam (Near-InfraRed Camera). Observations in the infrared reveal the galaxy’s creeping tendrils of gas, dust and stars. The bright blue spots reveal countless individual stars, while the bright yellow regions that weave throughout the galaxy indicate concentrations of active stellar nurseries, where new stars are forming. The orange-red areas indicate the distribution of a type of carbon-based compounds known as polycyclic aromatic hydrocarbons (or PAHs) — the MIRI F770W filter is particularly suited to imaging these important molecules. The bright red spots correspond to regions rich in hydrogen that have been ionised by the radiation from the newly formed stars. The diffuse gradient of blue light around the central region shows the distribution of older stars. The compact light-blue regions within the red ionised gas, mostly concentrated in the galaxy’s outer region, show the distribution of young star clusters.

NGC 4449 was observed by Webb as part of a series of observations collectively titled Feedback in Emerging extrAgalactic Star clusTers, or FEAST (PI: A. Adamo). Two other targets of the FEAST programme, M51, and M83, were the subjects of previous ESA/Webb Picture of the Month images in 2023.

[Image Description: A close view of the central area of a dwarf galaxy. A huge number of stars fill the whole galaxy as tiny glowing points. They are brightest around the galaxy’s shining core. Thick clouds of gas and dust billow out across the scene, curling like moving flames. They glow in warm colours following their location: orange around the galaxy’s core, and around glowing star clusters in the bottom-left, and dark red elsewhere.]

Star-studded cluster

Wed, 01 May 2024 10:00:00 +0200

This new image from the NASA/ESA/CSA James Webb Space Telescope features NGC 6440, a globular cluster that resides roughly 28 000 light-years from Earth in the constellation Sagittarius. The object was first discovered by William Herschel in May of 1786.

Globular clusters like NGC 6440 are roughly spherical, tightly packed, collections of old stars bound together by gravity. They can be found throughout galaxies, but often live on the outskirts. They hold hundreds of thousands to millions of stars that are on average about one light-year apart, but they can be as close together as the size of our Solar System. NGC 6440 is known to be a high-mass and metal-rich cluster that formed and is orbiting within the Galactic bulge, which is a dense, near-spherical region of old stars in the inner part of the Milky Way.

This image was obtained with 2023 data from Webb’s Near-InfraRed Camera (NIRCam) as part of an observation programme to explore the stars in the cluster and to investigate details of the cluster’s pulsars. A pulsar is a highly magnetised, rotating neutron star that emits a beam of electromagnetic radiation from their magnetic poles. To us, that beam appears as a short burst or pulse as the star rotates. Pulsars spin extremely fast. Astronomers have clocked the fastest pulsars at more than 716 rotations per second, but a pulsar could theoretically rotate as fast as 1500 rotations per second before slowly losing energy or breaking apart.

The new data obtained by the science team indicate the first evidence from Webb observations of abundance variations of helium and oxygen in stars in a globular cluster. These results open the window for future, in-depth investigations of other clusters in the Galactic bulge, which were previously infeasible with other telescope facilities given the significant crowding of stars in the cluster and the strong reddening caused by interstellar dust between the cluster and Earth.

[Image Description: A spherical collection of stars which fills the whole view. The cluster is dominated by a concentrated group of bright white stars at the centre, with several large yellow stars scattered throughout the image. Many of the stars have visible diffraction spikes. The background is black.]

A duo of starbursts in I Zwicky 18

Tue, 26 Mar 2024 10:00:00 +0100

The NASA/ESA/CSA James Webb Space Telescope has captured a spectacular view of the galaxy I Zwicky 18 (I Zw 18) in this new image. The galaxy was first identified by Swiss astronomer Fritz Zwicky in the 1930’s and resides roughly 59 million light-years from Earth.

This galaxy has gone through several sudden bursts of star formation. This galaxy is typical of the kinds of galaxies that inhabited the early Universe and it is classified as a dwarf irregular galaxy (much smaller than our Milky Way).

Two major starburst regions are embedded in the heart of the galaxy. The wispy brown filaments surrounding the central starburst region are bubbles of gas that have been heated by stellar winds and intense ultraviolet radiation unleashed by hot, young stars. A companion galaxy resides nearby to the dwarf galaxy, which can be seen at the bottom of the wider-field image. The companion may be interacting with the dwarf galaxy and may have triggered that galaxy's recent star formation. The orange blobs surrounding the dwarf galaxy are the dim glow from ancient fully formed galaxies at much larger distances.

This image was taken as part of a Webb programme to study the life cycle of dust in I Zw 18. Scientists are now building off of previous research with Hubble obtained at optical wavelengths, studying individual dusty stars in detail with Webb’s equivalent spatial resolution and sensitivity at infrared wavelengths. This galaxy is of particular interest as its content of elements heavier than helium is one of the lowest of all known galaxies in the local Universe. Such conditions are thought to be similar to those in some of the first star-forming galaxies at high redshift, so the Webb study of I Zw 18 should shed light on the life-cycle of stars and dust in the early Universe.

Although previously believed to have only just recently begun forming its first generation of stars, the NASA/ESA Hubble Space Telescope found fainter, older red stars contained within the galaxy, suggesting its star formation started at least one billion years ago and possibly as much as 10 billion years ago. The galaxy, therefore, may have formed at the same time as most other galaxies.

The new observations from Webb have revealed the detection of a set of candidate dusty evolved stars. It also provides details about Zw 18’s two dominant star-forming regions. Webb’s new data suggest that the dominant bursts of star formation in these regions occurred at different times. The strongest starburst activity is now believed to have happened more recently in the northwest lobe as compared to the galaxy’s southeast lobe. This is based on the relative populations of younger versus older stars found in each of the lobes.

[Image Description: Many small galaxies are scattered on a black background: mainly, white, oval-shaped and red, spiral galaxies. The image is dominated by a dwarf irregular galaxy, which hosts a bright region of white and blue stars at its core that appear as two distinct lobes. This region is surrounded by brown dusty filaments.]

ESAWebb Picture of The Month

A pair of planet-forming discs

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The stellar lifecycle in a nearby spiral

A celebrity cluster in the spotlight

Dwarf stars in a glittering sky

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A dance of dwarf galaxies

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The Red Spider Nebula, caught by Webb

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Webb brings cosmic lenses into focus

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Dusty wisps round a dusty disc

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A fresh look at a classic deep field

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A starburst shines in infrared

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A glimpse of the distant past

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Infrared, optical, and X-ray views of a galaxy group

Spying a spiral through a cosmic lens

Webb visits a star-forming spiral

Webb investigates a dusty and dynamic disc

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Close look at a local galaxy

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Tracing spiral arms in infrared

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Catching the edge of the Phantom Galaxy

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The exotic stellar population of Westerlund 1

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Peeking into Perseus

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The hidden intricacies of Messier 106

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Jewelled ring

Fireworks of stellar starbursts

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Star-studded cluster

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A duo of starbursts in I Zwicky 18

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