Webb finds surprises in Spiderweb protocluster field
Using the NASA/ESA/CSA James Webb Space Telescope, an international team of astronomers have found new galaxies in the Spiderweb protocluster. Their characteristics shed light on the growth of galaxies in these large cosmic cities, with the finding that gravitational interactions in these dense regions are not as important as previously thought.
Using the NASA/ESA/CSA James Webb Space Telescope, an international team of astronomers have found new galaxies in the Spiderweb protocluster. Their characteristics shed light on the growth of galaxies in these large cosmic cities, with the finding that gravitational interactions in these dense regions are not as important as previously thought. With the use of Webb’s capabilities, astronomers have now sought to better understand this protocluster and to reveal new galaxies within it. Infrared radiation passes more freely through cosmic dust than visible light, which is scattered by the dust. Because Webb can see infrared light very well, scientists used it to observe regions of the Spiderweb that were previously hidden to us by cosmic dust, and to find out to what degree this dust obscures them. This image shows the Spiderweb protocluster as seen by Webb’s NIRCam (Near-InfraRed Camera). Credit: ESA/Webb, NASA & CSA, H. Dannerbauer
Astronomers explore galaxy populations and uncover their physical characteristics across large-scale structures to better understand the build-up of galaxies and how their environments shape their assembly. The Spiderweb protocluster is a well-studied object in the early Universe. Its light has travelled over 10 billion years to reach us, and it shows us a galaxy cluster in formation, composed of more than a hundred known galaxies.
With the use of Webb’s capabilities, astronomers have now sought to better understand this protocluster and to reveal new galaxies inside it. Infrared light passes more freely through cosmic dust than visible light, which is scattered by the dust. Because Webb can see infrared light very well, scientists used it to observe regions of the Spiderweb that were previously hidden to us by cosmic dust, and to find out to what degree this dust obscures them.
“We are observing the build-up of one the largest structures in the Universe, a city of galaxies in construction,” explained Jose M. Pérez-Martínez of the Institute of Astrophysics of the Canary Islands (Instituto de Astrofísica de Canarias) and the University of La Laguna (Universidad de La Laguna in Spain). “We know that most galaxies in local galaxy clusters (the biggest metropolises of the Universe) are old and not very active, whereas in this work we are looking at these objects during their adolescence. As this city in construction grows, their physical properties will also be affected. Now, Webb is giving us new insights into the build-up of such structures for the first time.”
Using the NASA/ESA/CSA James Webb Space Telescope, an international team of astronomers have found new galaxies in the Spiderweb protocluster. Their characteristics shed light on the growth of galaxies in these large cosmic cities, with the finding that gravitational interactions in these dense regions are not as important as previously thought. With the use of Webb’s capabilities, astronomers have now sought to better understand this protocluster and to reveal new galaxies within it. Infrared radiation passes more freely through cosmic dust than visible light, which is scattered by the dust. Because Webb can see infrared light very well, scientists used it to observe regions of the Spiderweb that were previously hidden to us by cosmic dust, and to find out to what degree this dust obscures them. This annotated image shows the galaxy distribution in the Spiderweb protocluster as seen by Webb’s NIRCam (Near-InfraRed Camera). The galaxies are annotated by white circles, and the collection of gravitationally-bound galaxies is identified in the centre of the image. A selection of these galaxies are featured as individual close-ups at the bottom of the image. Credit: ESA/Webb, NASA & CSA, H. Dannerbauer
Webb enabled the team to study the hydrogen gas using a powerful diagnostic tracer that cannot be studied from ground-based observations. That allowed the team to reveal new, strongly obscured galaxies belonging to the cluster and to study how much they were obscured. This was accomplished using only about 3.5 hours of Webb’s observing time.
“As expected, we found new galaxy cluster members, but we were surprised to find more than expected,” explained Rhythm Shimakawa of Waseda University in Japan. “We found that previously-known galaxy members (similar to the typical star-forming galaxies like our Milky Way galaxy) are not as obscured or dust-filled as previously expected, which also came as a surprise.”
“This can be explained by the fact that the growth of these typical galaxies is not triggered primarily by galaxy interactions or mergers that induce star-formation,” added Helmut Dannerbauer of the Institute of Astrophysics of the Canary Islands (Instituto de Astrofísica de Canarias in Spain). “We now figure this can instead be explained by star formation that is fueled through gas accumulating at different locations all across the object’s large-scale structure.”
Using the NASA/ESA/CSA James Webb Space Telescope, an international team of astronomers have found new galaxies in the Spiderweb protocluster. Their characteristics shed light on the growth of galaxies in these large cosmic cities, with the finding that gravitational interactions in these dense regions are not as important as previously thought. With the use of Webb’s capabilities, astronomers have now sought to better understand this protocluster and to reveal new galaxies within it. Infrared radiation passes more freely through cosmic dust than visible light, which is scattered by the dust. Because Webb can see infrared light very well, scientists used it to observe regions of the Spiderweb that were previously hidden to us by cosmic dust, and to find out to what degree this dust obscures them. This annotated image shows the galaxy distribution in the Spiderweb protocluster as seen by Webb’s NIRCam (Near-InfraRed Camera). The galaxies are annotated by white circles, and the collection of gravitationally-bound galaxies is identified in the centre of the image. Credit: ESA/Webb, NASA & CSA, H. Dannerbauer
The new results used Webb’s NIRCam observations (Cycle 1 programme #1572, PIs: H. Dannerbauer and Y. Koyama) and are featured in two papers that have been published today in the Astrophysical Journal. The team is planning to study the (new) galaxy cluster members in more detail and confirm their existence with spectroscopic observations using Webb.
Webb finds candidates for first young brown dwarfs outside the Milky Way, in the star cluster NGC 602
An international team of astronomers has used the NASA/ESA/CSA James Webb Space Telescope to detect the first rich population of brown dwarf candidates outside the Milky Way in the star cluster NGC 602.
Near the outskirts of the Small Magellanic Cloud, a satellite galaxy roughly 200 000 light-years from Earth, lies the young star cluster NGC 602. The local environment of this cluster is a close analogue of what existed in the early Universe, with very low abundances of elements heavier than hydrogen and helium. The existence of dark clouds of dense dust and the fact that the cluster is rich in ionised gas also suggest the presence of ongoing star formation processes. Together with its associated HII [1] region N90, which contains clouds of ionised atomic hydrogen, this cluster provides a valuable opportunity to examine star formation scenarios under dramatically different conditions from those in the solar neighbourhood.
An international team of astronomers, including Peter Zeidler, Elena Sabbi, Elena Manjavacas and Antonella Nota, used Webb to observe NGC 602 and they detected candidates for the first young brown dwarfs outside our Milky Way.
“Only with the incredible sensitivity and spatial resolution in the correct wavelength regime is it possible to detect these objects at such great distances,” shared lead author Peter Zeidler of AURA/STScI for the European Space Agency. “This has never been possible before and also will remain impossible from the ground for the foreseeable future.”
Brown dwarfs are the more massive cousins of giant gas planets (typically ranging from roughly 13 to 75 Jupiter masses, and sometimes lower). They are free-floating, meaning that they are not gravitationally bound to a star as exoplanets are. However, some of them share characteristics with exoplanets, like their atmospheric composition and storm patterns.
“Until now, we’ve known of about 3000 brown dwarfs, but they all live inside our own galaxy,” added team member Elena Manjavacas of AURA/STScI for the European Space Agency.
“This discovery highlights the power of using both Hubble and Webb to study young stellar clusters,” explained team member Antonella Nota, executive director of the International Space Science Institute in Switzerland and the previous Webb Project Scientist for ESA. “Hubble showed that NGC602 harbors very young low mass stars, but only with Webb we can finally see the extent and the significance of the substellar mass formation in this cluster. Hubble and Webb are an amazingly powerful telescope duo!”
“Our results fit very well with the theory that the mass distribution of bodies below the hydrogen burning limit is simply a continuation of the stellar distribution,” shared Zeidler. “It seems they form in the same way, they just don’t accrete enough mass to become a fully fledged star.”
The team’s data include a new image from Webb’s Near-InfraRed Camera (NIRCam) of NGC 602, which highlights the cluster stars, the young stellar objects, and the surrounding gas and dust ridges, as well as the gas and dust itself, while also showing the significant contamination by background galaxies and other stars in the Small Magellanic Cloud. These observations were made in April 2023.
“By studying the young metal-poor brown dwarfs newly discovered in NGC602, we are getting closer to unlocking the secrets of how stars and planets formed in the harsh conditions of the early Universe,“ added team member Elena Sabbi of NSF’s NOIRLab, the University of Arizona, and the Space Telescope Science Institute.
“These are the first substellar objects outside the Milky Way” added Manjavacas. “We need to be ready for new ground-breaking discoveries in these new objects!”
These observations were made as part of the JWST GO programme #2662 (PI: P. Zeidler). The results have been published in The Astrophysical Journal.
Near the outskirts of the Small Magellanic Cloud, a satellite galaxy roughly 200 000 light-years from Earth, lies the young star cluster NGC 602, which is featured in this new image from the NASA/ESA/CSA James Webb Space Telescope. This image includes data from Webb’s NIRCam (Near-InfraRed Camera) and MIRI (Mid-InfraRed Instrument). The local environment of this cluster is a close analogue of what existed in the early Universe, with very low abundances of elements heavier than hydrogen and helium. The existence of dark clouds of dense dust and the fact that the cluster is rich in ionised gas also suggest the presence of ongoing star formation processes. This cluster provides a valuable opportunity to examine star formation scenarios under dramatically different conditions from those in the solar neighbourhood. An international team of astronomers, including Peter Zeidler, Elena Sabbi, and Antonella Nota, used Webb to observe NGC 602 and detected candidates for the first young brown dwarfs outside our Milky Way. Credit: ESA/Webb, NASA & CSA, P. Zeidler, E. Sabbi, A. Nota, M. Zamani (ESA/Webb)
Notes
[1] Some of the most beautiful extended objects that we can see are known as HII regions, also called diffuse or emission nebulae. They contain mostly ionised hydrogen and are found throughout the interstellar medium in the Milky Way and in other galaxies.
Webb provides another look into galactic collisions at Arp 107
An interaction between an elliptical galaxy and a larger spiral galaxy, collectively known as Arp 107, seems to have given the spiral a happier outlook thanks to the two bright ‘eyes’ and the wide semicircular ‘smile’ that have resulted. This image is a composite, combining observations from Webb’s MIRI (Mid-InfraRed Instrument) and NIRCam (Near-InfraRed Camera).
NIRCam highlights the stars within both galaxies and reveals the connection between them: a transparent, white bridge of stars pulled from both galaxies during their passage. MIRI data, represented in orange-red, show star-forming regions and dust that is composed of soot-like organic molecules known as polycyclic aromatic hydrocarbons. MIRI also provides a snapshot of the bright nucleus of the large spiral, home to a supermassive black hole.
This image of Arp 107, obtained by Webb’s MIRI (Mid-InfraRed Instrument), reveals the supermassive black hole that lies in the centre of the large spiral galaxy to the right, as evidenced by the small, bright central ‘core’. This bright core, where the black hole is pulling much of the dust into lanes, also features Webb’s characteristic diffraction spikes, caused by the light that it emits interacting with the structure of the telescope itself. Perhaps the defining feature of the region, which MIRI reveals, are the millions of young stars that are forming, highlighted in blue. These stars are surrounded by dusty silicates and soot-like molecules known as polycyclic aromatic hydrocarbons. The small elliptical galaxy to the left, which has already completed much of its star formation, is composed of many of these organic molecules. Credit: NASA, ESA, CSA, STScI
The spiral galaxy is classified as a Seyfert galaxy, one of the two largest groups of active galaxies, along with galaxies that host quasars. Seyfert galaxies aren’t as luminous or as distant as quasars, so they are better places to study similar phenomena in lower-energy light, like infrared.
This region is much like the Cartwheel Galaxy, one of the first interacting galaxies that Webb observed. Arp 107 may have turned out very similar in appearance to the Cartwheel, but since the smaller elliptical galaxy had an off-centre collision instead of a direct hit, the spiral galaxy got away with only its spiral arms being disturbed.
This composite image of Arp 107, created with data from the James Webb Space Telescope’s NIRCam (Near-InfraRed Camera) and MIRI (Mid-InfraRed Instrument), reveals a wealth of information about the star formation taking place in these two galaxies and how they collided hundreds of million years ago. The near-infrared data, shown in white, show older stars, which shine brightly in both galaxies, as well as the tenuous gas bridge that runs between them. The vibrant background galaxies are also brightly illuminated at these wavelengths. On the other hand, MIRI data show the young stars and star-forming regions in vibrant orange and red. Our view in the mid-infrared provides the best view of the collision point, given the noticeable gap at the top of the spiral galaxy. This collision not only began a new bout of star formation in the region, but also produced an endearing smile. Credit: NASA, ESA, CSA, STScI
The collision isn’t as bad as it sounds. Although there was much star formation occurring before, collisions between galaxies can compress gas, improving the conditions needed for more stars to form. On the other hand, as Webb reveals, collisions also disperse a lot of gas, potentially depriving new stars of the material they need to form.
Webb has captured these galaxies in the process of merging, which will take hundreds of millions of years. As the two galaxies rebuild after the chaos of their collision, Arp 107 may lose its smile, but it will inevitably turn into something just as interesting for future astronomers to study.
Arp 107 is located 465 million light-years from Earth in the constellation Leo Minor.
The north and east compass arrows show the orientation of the image on the sky. Note that the relationship between north and east on the sky (as seen from below) is flipped relative to the direction arrows on a map of the ground (as seen from above). The scale bar is labelled in light-years, which is the distance that light travels in one Earth-year. (It takes 75 000 years for light to travel a distance equal to the length of the bar.) One light-year is equal to about 5.88 trillion miles or 9.46 trillion kilometres. The field of view shown in this image is approximately 450 000 light-years across. This image shows invisible near-infrared and mid-infrared wavelengths of light that have been translated into visible-light colours. The colour key shows which NIRCam and MIRI filters were used when collecting the light. The colour of each filter name is the visible light colour used to represent the infrared light that passes through that filter. Credit: NASA, ESA, CSA, STScI
Webb peers into the Extreme Outer Galaxy and the Digel Clouds
Within the Milky Way’s outskirts is a firecracker show of star formation. The NASA/ESA/CSA James Webb Space Telescope has examined the fringes of our Milky Way galaxy and Webb’s near- and mid-infrared imaging capabilities have enabled scientists to examine a star-forming area reminiscent of our galaxy during its early stages of formation.
The NASA/ESA/CSA James Webb Space Telescope has observed the very outskirts of our Milky Way galaxy. Known as the Extreme Outer Galaxy, this region is located more than 58 000 light-years from the Galactic centre. To learn more about how a local environment affects the star formation process within it, a team of scientists directed the telescope’s NIRCam (Near-InfraRed Camera) and MIRI (Mid-InfraRed Instrument) towards a total of four star-forming areas within Digel Clouds 1 and 2: 1A, 1B, 2N, and 2S. In the case of Cloud 2S, shown here, Webb revealed a luminous main cluster that contains newly formed stars. Several of these young stars are emitting extended jets of material from their poles. To the main cluster’s top right is a sub-cluster of stars, a feature that scientists previously suspected to exist but has now been confirmed with Webb. Additionally, the telescope revealed a deep sea of background galaxies and red nebulous structures that are being carved away by winds and radiation from nearby stars. Credit: NASA, ESA, CSA, STScI, M. Ressler (NASA-JPL)
Astronomers have directed the NASA/ESA/CSA James Webb Space Telescope to examine the outskirts of our Milky Way galaxy, a region scientists call the Extreme Outer Galaxy owing to its location more than 58 000 light-years away from the Galactic centre. For comparison, Earth is approximately 26 000 light-years from the centre.
A team of scientists used Webb’s NIRCam (Near-Infrared Camera) and MIRI (Mid-Infrared Instrument) to image selected regions within two molecular clouds known as Digel Clouds 1 and 2. Thanks to its high sensitivity and sharp resolution, Webb was able to resolve these areas, which are hosts to star clusters undergoing bursts of star formation, in unprecedented detail. Some of the details revealed by these data include components of the clusters such as very young (Class 0) protostars, outflows and jets, and distinctive nebular structures.
These Webb observations are enabling scientists to study star formation in the outer Milky Way at the same level of detail as observations of star formation in our own solar neighbourhood.
Stars in the making
Although the Digel Clouds are within our galaxy, they are relatively poor in elements heavier than hydrogen and helium. This composition makes them similar to dwarf galaxies and our own Milky Way in its early history. The team therefore took the opportunity to use Webb to capture the activity in four clusters of young stars within Digel Clouds 1 and 2: 1A, 1B, 2N, and 2S.
In Cloud 2S, Webb captured the main cluster containing young, newly formed stars. This dense area is quite active and several stars are emitting extended jets of material along their poles. Additionally, while scientists previously suspected a sub-cluster might be present within the cloud, Webb’s imaging capabilities confirmed its existence for the first time. Webb’s data reveal that there are multiple jets shooting out in different directions from this cluster of stars.
The saga of stars
This Webb imagery of the Extreme Outer Galaxy and the Digel Clouds is just a starting point for the team. They intend to revisit this Milky Way outpost to find answers to a variety of current questions, including the relative abundance of stars of various masses within Extreme Outer Galaxy star clusters, a measurement that would help astronomers understand how a particular environment can influence different types of stars during their formation.
Though the story of star formation is complex and some chapters are still shrouded in mystery, Webb is gathering clues and helping astronomers unravel this intricate tale.
The observations were taken as part of Guaranteed Time Observation program 1237.
Annotated image of Digel Cloud 2S captured by Webb’s NIRCam (Near-Infrared Camera) and MIRI (Mid-Infrared Instrument), with compass arrows, a scale bar, colour key, and graphic overlays for reference. The north and east compass arrows show the orientation of the image on the sky. Note that the relationship between north and east on the sky (as seen from below) is flipped relative to direction arrows on a map of the ground (as seen from above). The scale bar is labelled in light-years and arcseconds. One light-year is equal to about 9.46 trillion kilometres. One arcsecond is equal to 1/3600 of one degree of arc (the full Moon has an angular diameter of about 0.5 degrees). The actual size of an object that covers one arcsecond on the sky depends on its distance from the telescope. This image shows invisible near- and mid-infrared wavelengths of light that have been translated into visible-light colours. The colour key shows which NIRCam and MIRI filters were used when collecting the light. The colour of each filter name is the visible light colour used to represent the infrared light that passes through that filter. In the main cluster are five white arrows, which highlight the paths of five protostar jets. Credit: NASA, ESA, CSA, STScI, M. Ressler (NASA-JPL)
Vivid portrait of interacting galaxies, Penguin and Egg, marks Webb’s second anniversary
The distorted spiral galaxy, the Penguin, and the compact elliptical galaxy, the Egg, are locked in an active embrace. A new near- and mid-infrared image from the James Webb Space Telescope, taken to mark its second year of science, shows that their interaction is marked by a faint upside-down U-shaped blue glow. The pair, known jointly as Arp 142, made their first pass between 25 and 75 million years ago — causing ‘fireworks’, or new star formation, in the Penguin. In the most extreme cases, mergers can cause galaxies to form thousands of new stars per year for a few million years. For the Penguin, research has shown that about 100 to 200 stars have formed per year. By comparison, our Milky Way galaxy (which is not interacting with a galaxy of the same size) forms roughly six to seven new stars per year. This gravitational shimmy also remade the Penguin’s appearance. Its coiled spiral arms unwound, and gas and dust were pulled in an array of directions, like it was releasing confetti. It is rare for individual stars to collide when galaxies interact (space is vast), but the galaxies’ mingling disrupts their stars’ orbits. Today, the Penguin’s galactic centre looks like an eye set within a head, and the galaxy has prominent star trails that take the shape of a beak, backbone, and fanned-out tail. A faint, but prominent dust lane extends from its beak down to its tail. Despite the Penguin appearing far larger than the Egg, these galaxies have approximately the same mass. This is one reason why the smaller-looking Egg hasn’t yet merged with the Penguin. (If one was less massive, it may have merged earlier.) The oval Egg is filled with old stars, and little gas and dust, which is why it isn’t sending out ‘streamers’ or tidal tails of its own and instead has maintained a compact oval shape. If you look closely, the Egg has four prominent diffraction spikes — the galaxy’s stars are so concentrated that it gleams. The background of this image is overflowing with far more distant galaxies. This is a testament to the sensitivity and resolution of Webb’s infrared cameras. Arp 142 lies 326 million light-years from Earth in the constellation Hydra. Credit: NASA, ESA, CSA, STScI
A duo of interacting galaxies known as Arp 142 commemorates the second science anniversary of the NASA/ESA/CSA James Webb Space Telescope. Their ongoing interaction was set in motion between 25 and 75 million years ago, when the Penguin (individually catalogued as NGC 2936) and the Egg (NGC 2937) completed their first pass. They will go on to shimmy and sway, completing several additional loops before merging into a single galaxy hundreds of millions of years from now.
The James Webb Space Telescope takes constant observations, including images and highly detailed data known as spectra. Its operations have led to a ‘parade’ of discoveries by astronomers around the world. It has never felt more possible to explore every facet of the Universe.
The telescope’s specialisation in capturing infrared light – which is beyond what our own eyes can detect – shows these galaxies, collectively known as Arp 142, locked in a slow cosmic dance. Webb’s observations (which combine near- and mid-infrared light from Webb’s NIRCam [Near-InfraRed Camera] and MIRI [Mid-Infrared Instrument], respectively) clearly show that they are joined by a blue haze that is a mix of stars and gas, a result of their mingling.
The distorted spiral galaxy at the centre, the Penguin, and the compact elliptical galaxy at the left, the Egg, are locked in an active embrace. A new near- and mid-infrared image from the James Webb Space Telescope, taken to mark its second year of science, shows that their interaction is marked by a faint upside-down U-shaped blue glow. The pair, known jointly as Arp 142, made their first pass between 25 and 75 million years ago — causing ‘fireworks’, or new star formation, in the Penguin. In the most extreme cases, mergers can cause galaxies to form thousands of new stars per year for a few million years. For the Penguin, research has shown that about 100 to 200 stars have formed per year. By comparison, our Milky Way galaxy (which is not interacting with a galaxy of the same size) forms roughly six to seven new stars per year. This gravitational shimmy also remade the Penguin’s appearance. Its coiled spiral arms unwound, and gas and dust were pulled in an array of directions, like it was releasing confetti. It is rare for individual stars to collide when galaxies interact (space is vast), but the galaxies’ mingling disrupts their stars’ orbits. Today, the Penguin’s galactic centre looks like an eye set within a head, and the galaxy has prominent star trails that take the shape of a beak, backbone, and fanned-out tail. A faint, but prominent dust lane extends from its beak down to its tail. Despite the Penguin appearing far larger than the Egg, these galaxies have approximately the same mass. This is one reason why the smaller-looking Egg hasn’t yet merged with the Penguin. (If one was less massive, it may have merged earlier.) The oval Egg is filled with old stars, and little gas and dust, which is why it isn’t sending out ‘streamers’ or tidal tails of its own and instead has maintained a compact oval shape. If you look closely, the Egg has four prominent diffraction spikes — the galaxy’s stars are so concentrated that it gleams. Now, find the bright, edge-on galaxy at top right. It may look like a party crasher, but it’s not nearby. Cataloged PGC 1237172, it lies 100 million light-years closer to Earth. It is relatively young and isn’t overflowing with dust, which is why it practically disappears in Webb’s mid-infrared view. The background of this image is overflowing with far more distant galaxies. This is a testament to the sensitivity and resolution of Webb’s infrared cameras. Arp 142 lies 326 million light-years from Earth in the constellation Hydra. Credit: NASA, ESA, CSA, STScI
Let’s dance
Before their first approach, the Penguin held the shape of a spiral. Today, its galactic centre gleams like an eye, its unwound arms now shaping a beak, head, backbone, and fanned-out tail.
Like all spiral galaxies, the Penguin is still very rich in gas and dust. The galaxies’ ‘dance’ pulled gravitationally on the Penguin’s thinner areas of gas and dust, causing them to crash in waves and form stars. Look for those areas in two places: what looks like a fish in its ‘beak’ and the ‘feathers’ in its “‘tail’.
Surrounding these newer stars is smoke-like material that includes carbon-containing molecules, known as polycyclic aromatic hydrocarbons, which Webb is exceptional at detecting. Dust, seen as fainter, deeper orange arcs also swoops from its beak to tail feathers.
Webb’s mid-infrared view of interacting galaxies Arp 142 seems to sing in primary colours. The background of space is like a yawning darkness speckled with bright, multi-coloured beads. This image was taken by MIRI, the telescope’s Mid-InfraRed Instrument, which astronomers use to study cooler and older objects, dust, and extremely distant galaxies. Here, the Egg appears as an exceptionally small teal oval with gauzy layers. Mid-infrared light predominantly shows the oldest stars in the elliptical galaxy, which has lost or used up most of its gas and dust. This is why the view is so different from the combined image, which includes near-infrared light. At right, the Penguin’s shape is relatively unchanged. The MIRI image shows all the gas and dust that has been distorted and stretched, as well as the smoke-like material, in blue, that includes carbon-containing molecules, known as polycyclic aromatic hydrocarbons. Next, look for the edge-on galaxy catalogued PGC 1237172 at the top right — a dim, hazy line. Find it by looking for the bright blue star with small diffraction spikes positioned over the top of its left edge. This galaxy nearly disappears in mid-infrared light because its stars are very young and the galaxy isn’t overflowing with dust. Now, scan the full image left to right to spot distant galaxies in the background. The red objects are encased in thick layers of dust. Some are spiral galaxies and others are more distant galaxies that can only be detected as dots or smudges. Green galaxies are laden with dust and are farther away. Bluer galaxies are closer. Zoom in carefully to see if a blue dot has minuscule diffraction spikes — those are stars, not galaxies. Credit: NASA, ESA, CSA, STScI
In contrast, the Egg’s compact shape remains largely unchanged. As an elliptical galaxy, it is filled with ageing stars, and has a lot less gas and dust that can be pulled away to form new stars. If both were spiral galaxies, each would end the first ‘twist’ with new star formation and twirling curls, known as tidal tails.
Another reason for the Egg’s undisturbed appearance is that these galaxies have approximately the same mass, which is why the smaller-looking elliptical wasn’t consumed or distorted by the Penguin.
It is estimated that the Penguin and the Egg are about 100 000 light-years apart — quite close in astronomical terms. For context, the Milky Way galaxy and our nearest neighbour, the Andromeda Galaxy, are about 2.5 million light-years apart, about 30 times the distance. They too will interact, but not for about 4 billion years.
The distorted spiral galaxy at the centre, the Penguin, and the compact elliptical galaxy at the left, the Egg, are locked in an active embrace. A new near- and mid-infrared image from the James Webb Space Telescope, taken to mark its second year of science, shows that their interaction is marked by a faint upside-down U-shaped blue glow. The pair, known jointly as Arp 142, made their first pass between 25 and 75 million years ago — causing ‘fireworks’, or new star formation, in the Penguin. In the most extreme cases, mergers can cause galaxies to form thousands of new stars per year for a few million years. For the Penguin, research has shown that about 100 to 200 stars have formed per year. By comparison, our Milky Way galaxy (which is not interacting with a galaxy of the same size) forms roughly six to seven new stars per year. This gravitational shimmy also remade the Penguin’s appearance. Its coiled spiral arms unwound, and gas and dust were pulled in an array of directions, like it was releasing confetti. It is rare for individual stars to collide when galaxies interact (space is vast), but the galaxies’ mingling disrupts their stars’ orbits. Today, the Penguin’s galactic centre looks like an eye set within a head, and the galaxy has prominent star trails that take the shape of a beak, backbone, and fanned-out tail. A faint, but prominent dust lane extends from its beak down to its tail. Despite the Penguin appearing far larger than the Egg, these galaxies have approximately the same mass. This is one reason why the smaller-looking Egg hasn’t yet merged with the Penguin. (If one was less massive, it may have merged earlier.) The oval Egg is filled with old stars, and little gas and dust, which is why it isn’t sending out ‘streamers’ or tidal tails of its own and instead has maintained a compact oval shape. If you look closely, the Egg has four prominent diffraction spikes — the galaxy’s stars are so concentrated that it gleams. Now, find the bright, edge-on galaxy at top right. It may look like a party crasher, but it’s not nearby. Cataloged PGC 1237172, it lies 100 million light-years closer to Earth. It is relatively young and isn’t overflowing with dust, which is why it practically disappears in Webb’s mid-infrared view. The background of this image is overflowing with far more distant galaxies. This is a testament to the sensitivity and resolution of Webb’s infrared cameras. Arp 142 lies 326 million light-years from Earth in the constellation Hydra. Credit: NASA, ESA, CSA, STScI
In the top right of the image is an edge-on galaxy, catalogued PGC 1237172, which resides 100 million light-years closer to Earth. It’s also quite young, teeming with new, blue stars. In Webb’s mid-infrared-only image, PGC 1237172 practically disappears. Mid-infrared light largely captures cooler, older stars and an incredible amount of dust. Since the galaxy’s stellar population is so young, it ‘vanishes’ in mid-infrared light.
This image shows two views of Arp 142 (nicknamed the Penguin and the Egg). The image on the left from the NASA/ESA Hubble Space Telescope shows the target in 2013. On the right is the NASA/ESA/CSA James Webb Space Telescope’s view of the same region in near-infrared light with the NIRCam instrument. Both images are made up of several filters. The process of applying colour to Webb’s images is remarkably similar to the approach used for Hubble: the shortest wavelengths are assigned blue and the longest wavelengths are assigned red. For Webb, image processors translate near-infrared light images, in order, to visible colours. Both telescopes take high-resolution images, so there are many features to explore. In Hubble’s visible light image, a dark brown dust lane begins across the Penguin’s ‘beak’ and extends through its body and along its back. In Webb’s near-infrared view, this dust lane is significantly fainter. Linger on Webb’s image. A faint upside-down U shape joins the pair of galaxies. This is a combination of stars, gas, and dust that continues to mix as the galaxies mingle. In Hubble’s view, notice there is a clearer gap between the Penguin’s ‘beak’ and the top of the Egg. Toward the bottom of the Penguin’s tail are several prominent spiral galaxies, though there are a few more in Webb’s image. The Egg itself looks similar in both images, but in Webb’s view, the galaxy shines so brightly that it causes diffraction spikes to slightly extend its gleam. The galaxy at top right appears about the same size, but many more pinpricks of stars appear in Webb’s view. Now compare the backgrounds. Hubble shows many distant galaxies in visible light, though areas in the corners that are completely black were outside the telescope’s field of view. Many more distant galaxies gleam in Webb’s infrared image. This is a testament to the sensitivity and resolution of Webb’s near-infrared camera, and the advantages of infrared light. Light from distant galaxies is stretched as it travels across the Universe, so a significant portion of their light can only be detected at longer wavelengths. Explore Webb’s near- and mid-infrared light image and its mid-infrared light-only image. Credit: NASA, ESA, CSA, STScI
Webb’s image is also overflowing with distant galaxies. Some have spiral and oval shapes, like those threaded throughout the Penguin’s ‘tail feathers’, while others scattered throughout are shapeless dots. This is a testament to the sensitivity and resolution of the telescope’s infrared instruments. (Compare Webb’s view to the 2013 image from the NASA/ESA Hubble Space Telescope here.) Even though these observations only took a few hours, Webb revealed far more distant, redder, and dustier galaxies than previous telescopes — one more reason to expect Webb to continue to expand our understanding of everything in the Universe.
Arp 142 lies 326 million light-years from Earth in the constellation Hydra.
This image of interacting galaxies Arp 142, captured by the James Webb Space Telescope’s NIRCam (Near-InfraRed Camera) and MIRI (Mid-InfraRed Instrument), shows compass arrows, a scale bar, and a colour key for reference. The north and east compass arrows show the orientation of the image on the sky. Note that the relationship between north and east on the sky (as seen from below) is flipped relative to direction arrows on a map of the ground (as seen from above). The scale bar is labelled in light-years, which is the distance that light travels in one Earth-year. (It takes three years for light to travel a distance equal to the length of the scale bar.) One light-year is equal to about 9.46 trillion kilometres. The scale bar is also labelled in arcseconds, which is a measure of angular distance on the sky. One arcsecond is equal to an angular measurement of 1/3600 of one degree. There are 60 arcminutes in a degree and 60 arcseconds in an arcminute. (The full Moon has an angular diameter of about 30 arcminutes.) The actual size of an object that covers one arcsecond on the sky depends on its distance from the telescope. This image shows invisible near- and mid-infrared wavelengths of light that have been translated into visible-light colours. The colour key shows which NIRCam and MIRI filters were used when collecting the light. The name of each filter is the visible light colour used to represent the infrared light that passes through that filter. Credit: NASA, ESA, CSA, STScI
Webb has continued to produce incredible images of the cosmos, from the detailed beauty of the Ring Nebula, to supernova remnant Cassiopeia A, to a team effort with the the NASA/ESA Hubble Space Telescope and ESA’s Euclid telescope looking at the iconic Horsehead Nebula. Webb imagery was also combined with visible light observations from Hubble to create one of the most comprehensive views of the Universe ever, an image of galaxy cluster MACS 0416.
This image of interacting galaxies Arp 142, captured by the James Webb Space Telescope’s MIRI (Mid-Infrared Instrument), shows compass arrows, scale bar, and colour key for reference. The north and east compass arrows show the orientation of the image on the sky. Note that the relationship between north and east on the sky (as seen from below) is flipped relative to direction arrows on a map of the ground (as seen from above). The scale bar is labelled in light-years, which is the distance that light travels in one Earth-year. (It takes three years for light to travel a distance equal to the length of the scale bar.) One light-year is equal to about 9.46 trillion kilometres. The scale bar is also labelled in arcminutes, which is a measure of angular distance on the sky. One arcsecond is equal to an angular measurement of 1/3600 of one degree. There are 60 arcminutes in a degree and 60 arcseconds in an arcminute. (The full Moon has an angular diameter of about 30 arcminutes.) The actual size of an object that covers one arcsecond on the sky depends on its distance from the telescope. This image shows invisible near- and mid-infrared wavelengths of light that have been translated into visible-light colours. The colour key shows which NIRCam and MIRI filters were used when collecting the light. The name of each filter is the visible light colour used to represent the infrared light that passes through that filter. Credit: NASA, ESA, CSA, STScI
First of its kind detection made in striking new Webb image: alignment of bipolar jets confirms star formation theories in Serpens Nebula
For the first time, a phenomenon astronomers have long hoped to image directly has been captured by the NASA/ESA/CSA James Webb Space Telescope’s Near-InfraRed Camera (NIRCam). In this stunning image of the Serpens Nebula, the discovery lies in the northern area of this young, nearby star-forming region.
In this image of the Serpens Nebula from the Near-InfraRed Camera (NIRCam) on the NASA/ESA/CSA James Webb Space Telescope, astronomers found a grouping of aligned protostellar outflows within one small region (the top left corner). In the Webb image, these jets are identified by bright red clumpy streaks, which are shockwaves caused when the jet hits the surrounding gas and dust. The Serpens Nebula, located 1 300 light-years from Earth, is home to a particularly dense cluster of newly forming stars (around 100 000 years old), some of which will eventually grow to the mass of our Sun. This region has been home to other coincidental discoveries, including the flapping ‘Bat Shadow’, which earned its name when 2020 data from the NASA/ESA Hubble Space Telescope revealed it to flap, or shift. This feature is visible at the centre of the Webb image. To the right of the ‘Bat Shadow’ lies another intriguing feature—an eye-shaped crevice, which appears as if a star is bursting through. However, astronomers say looks may be deceiving here. This could just be where gases of different densities are layered on top of one another, similar to what is seen in the famous Pillars of Creation. And to the right of that, an extremely dark patch could be a similar occurrence. The gas and dust here are so dense in comparison to the rest of the region that no near-infrared light is getting through. Credit: NASA, ESA, CSA, STScI, K. Pontoppidan (NASA’s Jet Propulsion Laboratory), J. Green (Space Telescope Science Institute)
The astronomers found an intriguing group of protostellar outflows, formed when jets of gas spewing from newborn stars collide with nearby gas and dust at high speeds. Typically these objects have a variety of orientations within one region. Here, however, they are all slanted in the same direction, to the same degree, like sleet pouring down during a storm.
The discovery of these aligned objects, made possible only by Webb’s exquisite spatial resolution and sensitivity at near-infrared wavelengths, is providing information about the fundamentals of how stars are born.
So just how does the alignment of the stellar jets relate to the rotation of the star? As an interstellar gas cloud collapses in on itself to form a star, it spins more rapidly. The only way for the gas to continue moving inward is for some of the spin (known as angular momentum) to be removed. A disc of material forms around the young star to transport material down, like a whirlpool around a drain. The swirling magnetic fields in the inner disc launch some of the material into twin jets that shoot outward in opposite directions, perpendicular to the disc of material.
In the Webb image, these jets are identified by bright red clumpy streaks, which are shockwaves caused when the jet hits the surrounding gas and dust. Here, the red colour indicates the presence of molecular hydrogen and carbon monoxide. Webb can image these extremely young stars and their outflows, which were previously obstructed at optical wavelengths.
Astronomers say there are a few forces that potentially can shift the direction of the outflows during this period of a young star’s life. One way is when binary stars spin around each other and wobble in orientation, twisting the direction of the outflows over time.
Stars of the Serpens Nebula
This image shows the centre of the Serpens Nebula as seen by the NASA/ESA/CSA James Webb Space Telescope’s Near-InfraRed Camera (NIRCam). The Serpens Nebula, located 1300 light-years from Earth, is home to a particularly dense cluster of newly forming stars (about 100 000 years old), some of which will eventually grow to the mass of our Sun. Webb’s image of this nebula revealed a grouping of aligned protostellar outflows (seen in the top left). These jets are identified by bright clumpy streaks that appear red, which are shock waves caused when the jet hits the surrounding gas and dust. Throughout this image filaments and wisps of different hues represent reflected starlight from still-forming protostars within the cloud. In some areas, there is dust in front of that reflection, which appears here in an orange, diffuse shade. Credit: NASA, ESA, CSA, STScI, K. Pontoppidan (NASA’s Jet Propulsion Laboratory), J. Green (Space Telescope Science Institute)
The Serpens Nebula is only one or two million years old, which is very young in cosmic terms. It’s also home to a particularly dense cluster of newly forming stars (around 100 000 years old) at the centre of this image, some of which will eventually grow to the mass of our Sun.
Serpens is a reflection nebula, which means it’s a cloud of gas and dust that does not create its own light but instead shines by reflecting the light from stars close to or within the nebula.
So, throughout the region in this image, filaments and wisps of different hues represent reflected starlight from still-forming protostars within the cloud. In some areas there is dust in front of that reflection, which appears here in an orange, diffuse shade.
This image from the NASA/ESA/CSA James Webb Space Telescope shows a portion of the Serpens Nebula, where astronomers have discovered a grouping of aligned protostellar outflows. These jets are signified by bright clumpy streaks that appear red, which are shock waves from the jet hitting surrounding gas and dust. Here, the red colour represents the presence of molecular hydrogen and carbon monoxide. Typically these objects have a variety of orientations within one region. Here, however, they are all slanted in the same direction, to the same degree, like sleet pouring down during a storm. Researchers say the discovery of these aligned objects, made possible only by Webb’s exquisite spatial resolution and sensitivity at near-infrared wavelengths, is providing information about the fundamentals of how stars are born. Credit: NASA, ESA, CSA, STScI, K. Pontoppidan (NASA’s Jet Propulsion Laboratory), J. Green (Space Telescope Science Institute)
This region has been home to other coincidental discoveries, including the flapping ‘Bat Shadow’, which earned its name when 2020 data from the NASA/ESAHubble Space Space Telescope revealed it to flap, or shift. This feature is visible at the centre of the Webb image.
Future studies
The stunning image and the serendipitous discovery of the aligned objects are actually just the first step in this scientific programme. The team will now use Webb’s NIRSpec (Near-InfraRed Spectrograph) to investigate the chemical make-up of the cloud.
Astronomers are interested in determining how volatile chemicals survive star and planet formation. Volatiles are compounds that sublimate, or transition from a solid directly to a gas, at a relatively low temperature — including water and carbon monoxide. They’ll then compare their findings to the amounts found in protoplanetary discs of similar-type stars.
These observations were made as part of the Webb General Observer programme 1611 (PI: K. Pontoppidan). The team’s initial results have been published in the Astrophysical Journal.
This image of the Serpens Nebula, captured by Webb’s Near-InfraRed Camera (NIRCam), shows compass arrows, a scale bar and a colour key for reference. The north and east compass arrows show the orientation of the image on the sky. Note that the relationship between north and east on the sky (as seen from below) is flipped relative to the direction of arrows on a map of the ground (as seen from above). The scale bar is labelled in light-years, which is the distance that light travels in one Earth-year. One light-year is equal to about 9.46 trillion kilometres, or 5.88 trillion miles. This image shows invisible near-infrared wavelengths of light that have been translated into visible-light colours. The colour key shows which NIRCam filters were used when collecting the light. The colour of each filter name is the visible light colour used to represent the infrared light that passes through that filter. Credit: NASA, ESA, CSA, STScI, K. Pontoppidan (NASA’s Jet Propulsion Laboratory), J. Green (Space Telescope Science Institute)
Investigating the origins of the Crab Nebula with Webb
New data revise our view of this unusual supernova explosion.
The Crab Nebula is a nearby example of the debris left behind when a star undergoes a violent death in a supernova explosion. However, despite decades of study, this supernova remnant continues to maintain a degree of mystery: what type of star was responsible for the creation of the Crab Nebula, and what was the nature of the explosion? The NASA/ESA/CSA James Webb Space Telescope has provided a new view of the Crab, including the highest-quality infrared data yet available to aid scientists as they explore the detailed structure and chemical composition of the remnant. These clues are helping to unravel the unusual way that the star exploded about 1000 years ago.
Image of the Crab Nebula captured by Webb’s NIRCam and MIRI, with compass arrows, scale bar, and colour key for reference. The north and east compass arrows show the orientation of the image on the sky. Note that the relationship between north and east on the sky (as seen from below) is flipped relative to direction arrows on a map of the ground (as seen from above). The scale bar is labelled in light-years, which is the distance that light travels in one Earth-year. (It takes two years for light to travel a distance equal to the length of the bar.) One light-year is equal to about 9.46 trillion kilometres or 5.88 trillion miles. The field of view shown in this image is approximately 10 light-years across. This image shows invisible near-infrared and mid-infrared wavelengths of light that have been translated into visible-light colours. The colour key shows which components were observed by NIRCam and MIRI, and which visible-light colour is assigned to each feature. Credit: NASA, ESA, CSA, STScI, T. Temim (Princeton University)
A team of scientists used the NASA/ESA/CSA James Webb Space Telescope to parse the composition of the Crab Nebula, a supernova remnant located 6500 light-years away in the constellation Taurus. With the telescope’s MIRI (Mid-Infared Instrument) and NIRCam (Near-Infrared Camera), the team gathered data that are helping to clarify the Crab Nebula’s history.
The Crab Nebula is the result of a core-collapse supernova that was the death of a massive star. The supernova explosion itself was seen on Earth in 1054 CE and was bright enough to view during the daytime. The much fainter remnant observed today is an expanding shell of gas and dust, and an outflowing wind powered by a pulsar, a rapidly spinning and highly magnetised neutron star.
The Crab Nebula is also highly unusual. Its atypical composition and very low explosion energy have previously led astronomers to think it was an electron-capture supernova — a rare type of explosion that arises from a star with a less-evolved core made of oxygen, neon, and magnesium, rather than a more typical iron core.
Past research efforts have calculated the total kinetic energy of the explosion based on the quantity and velocities of the present-day ejecta. Astronomers deduced that the nature of the explosion was one of relatively low energy (less than one-tenth that of a normal supernova), and the progenitor star’s mass was in the range of eight to 10 solar masses — teetering on the thin line between stars that experience a violent supernova death and those that do not.
However, inconsistencies exist between the electron-capture supernova theory and observations of the Crab, particularly the observed rapid motion of the pulsar. In recent years, astronomers have also improved their understanding of iron-core-collapse supernovae and now think that this type can also produce low-energy explosions, providing the stellar mass is adequately low.
To lower the level of uncertainty about the Crab’s progenitor star and the nature of the explosion, the science team used Webb’s spectroscopic capabilities to home in on two areas located within the Crab’s inner filaments.
Theories predict that because of the different chemical composition of the core in an electron-capture supernova, the nickel to iron (Ni/Fe) abundance ratio should be much higher than the ratio measured in our Sun (which contains these elements from previous generations of stars). Studies in the late 1980s and early 1990s measured the Ni/Fe ratio within the Crab using optical and near-infrared data and noted a high Ni/Fe abundance ratio that seemed to favour the electron-capture supernova scenario.
The Webb telescope, with its sensitive infrared capabilities, is now advancing Crab Nebula research. The team used MIRI’s spectroscopic abilities to measure the nickel and iron emission lines, resulting in a more reliable estimate of the Ni/Fe abundance ratio. They found that the ratio was still elevated compared to the Sun, but only modestly so and much lower in comparison to earlier estimates.
The revised values are consistent with electron-capture, but do not rule out an iron-core-collapse explosion from a similarly low-mass star. (Higher-energy explosions from higher-mass stars are expected to produce Ni/Fe ratios closer to solar abundances.) Further observational and theoretical work will be needed to distinguish between these two possibilities.
Besides pulling spectral data from two small regions of the Crab Nebula’s interior to measure the abundance ratio, the telescope also observed the remnant’s broader environment to understand details of the synchrotron emission and the dust distribution.
The images and data collected by MIRI enabled the team to isolate the dust emission within the Crab and map it in high resolution for the first time. By mapping the warm dust emission with Webb, and even combining it with the Herschel Space Observatory’s data on cooler dust grains, the team created a well-rounded picture of the dust distribution: the outermost filaments contain relatively warmer dust, while cooler grains are prevalent near the centre.
The observations were taken as part of the Webb General Observer programme 1714.
The NASA/ESA/CSA James Webb Space Telescope dissected the Crab Nebula’s structure, aiding astronomers as they continue to evaluate leading theories about the supernova remnant’s origins. With the data collected by Webb’s NIRCam (Near-Infrared Camera) and MIRI (Mid-Infrared Instrument), a team of scientists were able to closely inspect some of the Crab Nebula’s major components. For the first time ever, astronomers mapped the warm dust emission throughout this supernova remnant. Represented here as fluffy magenta material, the dust grains form a cage-like structure that is most apparent toward the lower left and upper right portions of the remnant. Filaments of dust are also threaded throughout the Crab’s interior and sometimes coincide with regions of doubly ionised sulphur (sulphur III), coloured in green. Yellow-white mottled filaments, which form large loop-like structures around the supernova remnant’s centre, represent areas where dust and doubly ionised sulphur overlap. The dust’s cage-like structure helps constrain some, but not all of the ghostly synchrotron emission represented in blue. The emission resembles wisps of smoke, most notable toward the Crab’s centre. The thin blue ribbons follow the magnetic field lines created by the Crab’s pulsar heart — a rapidly rotating neutron star. Credit: NASA, ESA, CSA, STScI, T. Temim (Princeton University)
Webb hints at possible atmosphere surrounding 55 Cancri e, a rocky exoplanet
Researchers using the NASA/ESA/CSA James Webb Space Telescope may have detected atmospheric gases surrounding 55 Cancri e, a hot rocky exoplanet 41 light-years from Earth. This is the best evidence to date for the existence of a rocky planet atmosphere outside our Solar System.
Renyu Hu from NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California, USA, is the lead author of a paper published today in Nature.
“Webb is pushing the frontiers of exoplanet characterisation to rocky planets,” Hu said. “It is truly enabling a new type of science.”
Super-hot super-Earth 55 Cancri e
55 Cancri e is one of five known planets orbiting a Sun-like star in the constellation Cancer. With a diameter nearly twice that of Earth and a density slightly greater, the planet is classified as a super-Earth: larger than Earth, smaller than Neptune, and likely similar in composition to the rocky planets in our Solar System.
To describe 55 Cancri e as rocky, however, could give the wrong impression. The planet orbits so close to its star (about 2.25 million kilometres, or one twenty-fifth of the distance between Mercury and the Sun) that its surface is likely to be molten – a bubbling ocean of magma. In such a tight orbit, the planet is also likely to be tidally locked, with a dayside that faces the star at all times and a nightside in perpetual darkness.
In spite of numerous observations since it was discovered to transit in 2011, the question of whether or not 55 Cancri e has an atmosphere – or even could have one, given its high temperature and the continuous onslaught of stellar radiation and wind from its star – has gone unanswered.
“I’ve worked on this planet for more than a decade,” said Diana Dragomir, an exoplanet researcher at the University of New Mexico in the USA and a co-author of the study. “It’s been really frustrating that none of the observations we’ve been getting have robustly solved these mysteries. I am thrilled that we are finally getting some answers!”
Unlike gas-giant atmospheres, which are relatively easy to spot (the first was detected by the NASA/ESA Hubble Space Telescope more than two decades ago), thinner and denser atmospheres surrounding rocky planets have remained elusive.
Previous studies of 55 Cancri e using data from NASA’s now-retired Spitzer Space Telescope suggested the presence of a substantial atmosphere rich in volatiles (molecules that occur in gas form on Earth) like oxygen, nitrogen, and carbon dioxide. But researchers could not rule out another possibility: that the planet is bare, save for a tenuous shroud of vaporised rock, rich in elements like silicon, iron, aluminium, and calcium.
“The planet is so hot that some of the molten rock should evaporate,” explained Hu.
This artist’s concept shows what the exoplanet 55 Cancri e could look like. Also called Janssen, 55 Cancri e is a so-called super-Earth, a rocky planet significantly larger than Earth but smaller than Neptune, which orbits its star at a distance of only 2.25 million kilometres (0.015 astronomical units), completing one full orbit in less than 18 hours. In comparison, Mercury is 25 times farther from the Sun than 55 Cancri e is from its star. The system, which also includes four large gas-giant planets, is located about 41 light-years from Earth, in the constellation Cancer. Observations from Webb’s NIRCam and MIRI suggest that the planet may be surrounded by an atmosphere rich in carbon dioxide (CO2) or carbon monoxide (CO). Because it is so close to its star, the planet is extremely hot and is thought to be covered in molten rock. Researchers think that the gases that make up the atmosphere could have bubbled out of the magma. The star, 55 Cancri, is a K-type star nearly the same size and mass as the Sun, but slightly cooler and dimmer. It is just bright enough to see with the naked eye in a very dark sky. The star and planet are so close to each other that the star would appear 70 times wider in the planet’s sky than the Sun appears in our sky. In addition, because the planet is likely to be tidally locked, from any given point the star would appear fixed in the sky. This artist’s concept is based on new data gathered by NIRCam and MIRI as well as previous observations from other ground- and space-based telescopes, including NASA’s Hubble and the now-retired Spitzer space telescopes. Webb has not captured any images of the planet. Credit: NASA, ESA, CSA, R. Crawford (STScI)
Measuring subtle variations in infrared colours
To distinguish between the two possibilities, the team used Webb’s NIRCam (Near-Infrared Camera) and MIRI (Mid-Infrared Instrument) to measure 4- to 12-micron infrared light coming from the planet.
Although Webb cannot capture a direct image of 55 Cancri e, it can measure subtle changes in the light from the whole system as the planet orbits the star.
By subtracting the brightness during the secondary eclipse, when the planet is behind the star (starlight only), from the brightness when the planet is right beside the star (light from the star and planet combined), the team was able to calculate the amount of various wavelengths of infrared light coming from the dayside of the planet.
This method, known as secondary eclipse spectroscopy, is similar to that used by other research teams to search for atmospheres on other rocky exoplanets, like TRAPPIST-1 b.
This lightcurve shows the change in brightness of the 55 Cancri system as the rocky planet 55 Cancri e, the closest of the five known planets in the system, moves behind the star. This phenomenon is known as a secondary eclipse. When the planet is beside the star, the mid-infrared light emitted by both the star and the dayside of the planet reaches the telescope, and the system appears brighter. When the planet is behind the star, the light emitted by the planet is blocked and only the starlight reaches the telescope, causing the apparent brightness to decrease. Astronomers can subtract the brightness of the star from the combined brightness of the star and planet to calculate how much infrared light is coming from the dayside of the planet. This is then used to calculate the dayside temperature and infer whether or not the planet has an atmosphere. The graph shows data collected using the low-resolution spectroscopy mode on Webb’s Mid-Infrared Instrument (MIRI) in March 2023. Each of the purple data points shows the brightness of light ranging in wavelength from 7.5 to 11.8 microns, averaged over intervals of about five minutes. The grey line is the best fit, or model lightcurve that matches the data most closely. The decrease in brightness during the secondary eclipse is just 110 parts per million, or about 0.011 percent. The temperature of the planet calculated from this observation is about 1800 kelvins (around 1500 degrees Celsius), which is significantly lower than would be expected if the planet has no atmosphere or only a thin rock-vapour atmosphere. This relatively low temperature indicates that heat is being distributed from the dayside to the nightside of the planet, possibly by a volatile-rich atmosphere. Credit: NASA, ESA, CSA, J. Olmsted (STScI), A. Bello-Arufe (JPL)
55 Cancri e is cooler than expected
The first indication that 55 Cancri e could have a substantial atmosphere came from temperature measurements based on its thermal emission, the heat energy given off in the form of infrared light. If the planet is covered in dark molten rock with a thin veil of vaporised rock, or has no atmosphere at all, the dayside should be around 2200 degrees Celsius.
“Instead, the MIRI data showed a relatively low temperature of about 1540 degrees Celsius,” said Hu. “This is a very strong indication that energy is being distributed from the dayside to the nightside, most likely by a volatile-rich atmosphere.”
While currents of lava can carry some heat around to the nightside, they cannot move it efficiently enough to explain the cooling effect.
When the team looked at the NIRCam data, they saw patterns consistent with a volatile-rich atmosphere.
“We see evidence of a dip in the spectrum between 4 and 5 microns — less of this light is reaching the telescope,” explained co-author Aaron Bello-Arufe, also from JPL. “This suggests the presence of an atmosphere containing carbon monoxide or carbon dioxide, both of which absorb these wavelengths of light.”
A planet with no atmosphere or only vaporised rock in an atmosphere would not have this specific spectral feature.
“This is exciting news,” said co-author Yamila Miguel from Leiden Observatory and the Netherlands Institute for Space Research (SRON), both in the Netherlands. “We’ve spent the last ten years modelling different scenarios, trying to imagine what this world might look like. Finally getting some confirmation of our work is priceless!”
Bubbling magma ocean
The team thinks that the gases blanketing 55 Cancri e would be bubbling out from the interior, rather than being present since the planet’s formation.
“The primary atmosphere would be long gone because of the high temperature and intense radiation from the star,” said Bello-Arufe. “This would be a secondary atmosphere that is continuously replenished by the magma ocean. Magma is not only crystals and liquid rock, there’s a lot of dissolved gas in it, too.”
In all likelihood, any atmosphere surrounding the planet would be more complex and quite variable as a result of interactions with the magma ocean. In addition to carbon monoxide or carbon dioxide, there could be gases like nitrogen, water vapour, sulphur dioxide, some vaporised rock, and even short-lived clouds made of tiny droplets of lava condensed from the air.
While 55 Cancri e is far too hot to be habitable, researchers think it could provide a unique window for studying interactions between the atmospheres, surfaces and interiors of rocky planets, and perhaps provide insights into the early Earth, Venus and Mars, which are thought to have been covered in magma oceans in the past.
“Ultimately, we want to understand what conditions make it possible for a rocky planet to sustain a gas-rich atmosphere, a key ingredient for a habitable planet,” said Hu.
This research was conducted as part of Webb’s General Observers (GO) Program 1952. Analysis of additional secondary eclipse observations of 55 Cancri e are currently in progress. In the future, the team hopes to capture a full phase curve with Webb in order to map temperature differences from one side of the planet to the other, to get a better sense of the planet’s weather, climate and more detailed atmospheric conditions.
A thermal emission spectrum captured by Webb’s NIRCam (Near-Infrared Camera) in November 2022, and MIRI (Mid-Infrared Instrument) in March 2023, shows the brightness (y-axis) of different wavelengths of infrared light (x-axis) emitted by the super-Earth exoplanet 55 Cancri e. The spectrum shows that the planet may be surrounded by an atmosphere rich in carbon dioxide or carbon monoxide and other volatiles, not just vaporised rock. The graph compares data collected by NIRCam (orange dots) and MIRI (purple dots) to two different models. Model A, in red, shows what the emission spectrum of 55 Cancri e should look like if it has an atmosphere made of vaporised rock. Model B, in blue, shows what the emission spectrum should look like if the planet has a volatile-rich atmosphere outgassed from a magma ocean that has a volatile content similar to Earth’s mantle. Both MIRI and NIRCam data are consistent with the volatile-rich model. The amount of mid-infrared light emitted by the planet (MIRI) shows that its dayside temperature is significantly lower than it would be if it did not have an atmosphere to distribute heat from the dayside to the nightside. The dip in the spectrum between 4 and 5 microns (NIRCam data) can be explained by absorption of those wavelengths by carbon monoxide or carbon dioxide molecules in the atmosphere. The spectrum was made by measuring the brightness of 4- to 5-micron light with Webb’s NIRCam GRISM spectrometer, and 5- to 12-micron light with the MIRI low-resolution spectrometer, before, during and after the planet moved behind its star (the secondary eclipse ). The amount of each wavelength emitted by the planet (y-axis) was calculated by subtracting the brightness of the star alone (during the secondary eclipse) from the brightness of the star and planet combined (before and after the eclipse). Each observation lasted about eight hours. Note that the NIRCam data have been shifted vertically to align with Model B. Although the differences in brightness between each wavelength in the NIRCam band were derived from the observation (the data suggest a valley between 4 and 5 microns), the absolute brightness (the vertical position of that valley) could not be measured precisely because of noise in the data. Credit: NASA, ESA, CSA, J. Olmsted (STScI), R. Hu (JPL), A. Bello-Arufe (JPL), M. Zhang (University of Chicago), M. Zilinskas (SRON Netherlands Institute for Space Research)
Webb captures iconic Horsehead Nebula in unprecedented detail
The NASA/ESA/CSA James Webb Space Telescope has captured the sharpest infrared images to date of one of the most distinctive objects in our skies, the Horsehead Nebula. These observations show a part of the iconic nebula in a whole new light, capturing its complexity with unprecedented spatial resolution.
This image showcases three views of one of the most distinctive objects in our skies, the Horsehead Nebula. This object resides in part of the sky in the constellation Orion (The Hunter), in the western side of the Orion B molecular cloud. Rising from turbulent waves of dust and gas is the Horsehead Nebula, otherwise known as Barnard 33, which resides roughly 1300 light-years away. The first image (left), released in November 2023, features the Horsehead Nebula as seen by ESA’s Euclid telescope. Euclid captured this image of the Horsehead in about one hour, which showcases the mission’s ability to very quickly image an unprecedented area of the sky in high detail. The second image (middle) shows the NASA/ESA Hubble Space Telescope’s infrared view of the Horsehead Nebula, which was featured as the telescope’s 23rd anniversary image in 2013. This image captures plumes of gas in the infrared and reveals a beautiful, delicate structure that is normally obscured by dust. The third image (right) features a new view of the Horsehead Nebula from the NASA/ESA/CSA James Webb Space Telescope’s NIRCam (Near-InfraRed Camera) instrument. It is the sharpest infrared image of the object to date, showing a part of the iconic nebula in a whole new light, and capturing its complexity with unprecedented spatial resolution. Credit: ESA/Euclid/Euclid Consortium/NASA, image processing by J.-C. Cuillandre (CEA Paris-Saclay), G. Anselmi, NASA, ESA, and the Hubble Heritage Team (AURA/STScI), ESA/Webb, CSA, K. Misselt (University of Arizona) and A. Abergel (IAS/University Paris-Saclay, CNRS), M. Zamani (ESA/Webb)
Webb’s new images show part of the sky in the constellation Orion (The Hunter), in the western side of the Orion B molecular cloud. Rising from turbulent waves of dust and gas is the Horsehead Nebula, otherwise known as Barnard 33, which resides roughly 1300 light-years away.
The nebula formed from a collapsing interstellar cloud of material, and glows because it is illuminated by a nearby hot star. The gas clouds surrounding the Horsehead have already dissipated, but the jutting pillar is made of thick clumps of material that is harder to erode. Astronomers estimate that the Horsehead has about five million years left before it too disintegrates. Webb’s new view focuses on the illuminated edge of the top of the nebula’s distinctive dust and gas structure.
The Horsehead Nebula is a well-known photodissociation region, or PDR. In such a region ultraviolet light from young, massive stars creates a mostly neutral, warm area of gas and dust between the fully ionised gas surrounding the massive stars and the clouds in which they are born. This ultraviolet radiation strongly influences the gas chemistry of these regions and acts as the most important source of heat.
These regions occur where interstellar gas is dense enough to remain neutral, but not dense enough to prevent the penetration of far-ultraviolet light from massive stars. The light emitted from such PDRs provides a unique tool to study the physical and chemical processes that drive the evolution of interstellar matter in our galaxy, and throughout the Universe from the early era of vigorous star formation to the present day.
Owing to its proximity and its nearly edge-on geometry, the Horsehead Nebula is an ideal target for astronomers to study the physical structures of PDRs and the evolution of the chemical characteristics of the gas and dust within their respective environments, and the transition regions between them. It is considered one of the best objects in the sky to study how radiation interacts with interstellar matter.
The NASA/ESA/CSA James Webb Space Telescope has captured the sharpest infrared images to date of one of the most distinctive objects in our skies, the Horsehead Nebula. These observations show a part of the iconic nebula in a whole new light, capturing its complexity with unprecedented spatial resolution. Webb’s new images show part of the sky in the constellation Orion (The Hunter), in the western side of the Orion B molecular cloud. Rising from turbulent waves of dust and gas is the Horsehead Nebula, otherwise known as Barnard 33, which resides roughly 1300 light-years away. The nebula formed from a collapsing interstellar cloud of material, and glows because it is illuminated by a nearby hot star. The gas clouds surrounding the Horsehead have already dissipated, but the jutting pillar is made of thick clumps of material that is harder to erode. Astronomers estimate that the Horsehead has about five million years left before it too disintegrates. Webb’s new view focuses on the illuminated edge of the top of the nebula’s distinctive dust and gas structure. The Horsehead Nebula is a well-known photon-dominated region, or PDR. In such a region ultraviolet light from young, massive stars creates a mostly neutral, warm area of gas and dust between the fully ionised gas surrounding the massive stars and the clouds in which they are born. This ultraviolet radiation strongly influences the gas chemistry of these regions and acts as the most important source of heat. These regions occur where interstellar gas is dense enough to remain neutral, but not dense enough to prevent the penetration of far-ultraviolet light from massive stars. The light emitted from such PDRs provides a unique tool to study the physical and chemical processes that drive the evolution of interstellar matter in our galaxy, and throughout the Universe from the early era of vigorous star formation to the present day. Owing to its proximity and its nearly edge-on geometry, the Horsehead Nebula is an ideal target for astronomers to study the physical structures of PDRs and the evolution of the chemical characteristics of the gas and dust within their respective environments, and the transition regions between them. It is considered one of the best objects in the sky to study how radiation interacts with interstellar matter. This image was captured with Webb’s NIRCam (Near-InfraRed Camera) instrument. Credit: ESA/Webb, NASA, CSA, K. Misselt (University of Arizona) and A. Abergel (IAS/University Paris-Saclay, CNRS)
Thanks to Webb’s MIRI and NIRCam instruments, an international team of astronomers have revealed for the first time the small-scale structures of the illuminated edge of the Horsehead. They have also detected a network of striated features extending perpendicular to the PDR front and containing dust particles and ionised gas entrained in the photo-evaporative flow of the nebula. The observations have also allowed astronomers to investigate the effects of dust attenuation and emission, and to better understand the multidimensional shape of the nebula.
The NASA/ESA/CSA James Webb Space Telescope has captured the sharpest infrared images to date of one of the most distinctive objects in our skies, the Horsehead Nebula. These observations show a part of the iconic nebula in a whole new light, capturing its complexity with unprecedented spatial resolution. Webb’s new images show part of the sky in the constellation Orion (The Hunter), in the western side of the Orion B molecular cloud. Rising from turbulent waves of dust and gas is the Horsehead Nebula, otherwise known as Barnard 33, which resides roughly 1300 light-years away. The nebula formed from a collapsing interstellar cloud of material, and glows because it is illuminated by a nearby hot star. The gas clouds surrounding the Horsehead have already dissipated, but the jutting pillar is made of thick clumps of material that is harder to erode. Astronomers estimate that the Horsehead has about five million years left before it too disintegrates. Webb’s new view focuses on the illuminated edge of the top of the nebula’s distinctive dust and gas structure. The Horsehead Nebula is a well-known photon-dominated region, or PDR. In such a region ultraviolet light from young, massive stars creates a mostly neutral, warm area of gas and dust between the fully ionised gas surrounding the massive stars and the clouds in which they are born. This ultraviolet radiation strongly influences the gas chemistry of these regions and acts as the most important source of heat. These regions occur where interstellar gas is dense enough to remain neutral, but not dense enough to prevent the penetration of far-ultraviolet light from massive stars. The light emitted from such PDRs provides a unique tool to study the physical and chemical processes that drive the evolution of interstellar matter in our galaxy, and throughout the Universe from the early era of vigorous star formation to the present day. Owing to its proximity and its nearly edge-on geometry, the Horsehead Nebula is an ideal target for astronomers to study the physical structures of PDRs and the evolution of the chemical characteristics of the gas and dust within their respective environments, and the transition regions between them. It is considered one of the best objects in the sky to study how radiation interacts with interstellar matter. This image was captured with Webb’s MIRI (Mid-InfraRed Instrument). Credit: ESA/Webb, NASA, CSA, K. Misselt (University of Arizona) and A. Abergel (IAS/University Paris-Saclay, CNRS)
Next, astronomers intend to study the spectroscopic data that have been obtained of the nebula to evidence the evolution of the physical and chemical properties of the material observed across the nebula.
These observations were taken in the Webb GTO programme #1192 (PI: K. Misselt) and the results have been accepted for publication in Astronomy & Astrophysics (Abergel et al. 2024).
Webb probes Messier 82 (M82), an extreme starburst galaxy
Amid a galaxy teeming with new and young stars lies an intricate substructure
Annotated image of the starburst galaxy Messier 82 captured by Webb’s NIRCam (Near-Infrared Camera) instrument, with compass arrows, a scale bar, and colour key for reference. The north and east compass arrows show the orientation of the image on the sky. Note that the relationship between north and east on the sky (as seen from below) is flipped relative to direction arrows on a map of the ground (as seen from above). The scale bar is labelled in light-years. This image shows invisible near-infrared wavelengths of light that have been translated into visible-light colours. The colour key shows which NIRCam filters were used when collecting the light. The colour of each filter name is the visible light colour used to represent the infrared light that passes through that filter. Credit: NASA, ESA, CSA, STScI, A. Bolatto (UMD)
The NASA/ESA/CSA James Webb Space Telescope has set its sights on the starburst galaxy Messier 82 (M82), a small but mighty environment that features rapid star formation. By looking closer with Webb’s sensitive infrared capabilities, a team of scientists is getting to the very core of the galaxy, gaining a better understanding of how it is forming stars and how this extreme activity is affecting the galaxy as a whole.
An international team of astronomers has used the NASA/ESA/CSA James Webb Space Telescope to survey the starburst galaxy Messier 82 (M82). Located 12 million light-years away in the constellation Ursa Major, this galaxy is relatively compact in size but hosts a frenzy of star formation activity. For comparison, M82 is sprouting new stars 10 times faster than the Milky Way galaxy.
The team directed Webb’s NIRCam (Near-Infrared Camera) instrument toward the starburst galaxy’s centre, obtaining a closer look at the physical conditions that foster the formation of new stars.
“M82 has garnered a variety of observations over the years because it can be considered as the prototypical starburst galaxy,” said Alberto Bolatto, lead author of the study. “Both Spitzer and Hubble space telescopes have observed this target. With Webb’s size and resolution, we can look at this star-forming galaxy and see all of this beautiful new detail.”
Star formation continues to maintain a sense of mystery because it is shrouded by curtains of dust and gas, creating an obstacle to observing this process. Fortunately, Webb’s ability to peer in the infrared is an asset in navigating these murky conditions. Additionally, these NIRCam images of the very centre of the starburst were obtained using an instrument mode that prevented the very bright source from overwhelming the detector.
Astronomers used the NASA/ESA/CSA James Webb Space Telescope to look toward M82’s centre, where a galactic wind is being launched as a result of rapid star formation and subsequent supernovae. Studying the galactic wind can offer insight into how the loss of gas shapes the future growth of the galaxy. This image from Webb’s NIRCam (Near-Infrared Camera) instrument shows M82’s galactic wind via emission from sooty chemical molecules known as polycyclic aromatic hydrocarbons (PAHs). PAHs are very small dust grains that survive in cooler temperatures but are destroyed in hot conditions. The structure of the emission resembles that of hot, ionised gas, suggesting PAHs may be replenished by continued ionisation of molecular gas. In this image, light at 3.35 microns is coloured red, 2.50 microns is green, and 1.64 microns is blue (filters F335M, F250M, and F164N, respectively). Credit: NASA, ESA, CSA, STScI, A. Bolatto (UMD)
While dark brown tendrils of dust are threaded throughout M82’s glowing white core even in this infrared view, Webb’s NIRCam has revealed a level of detail that has historically been obscured. Looking closer toward the centre, small specks depicted in green denote concentrated areas of iron, most of which are supernova remnants. Small patches that appear red signify regions where molecular hydrogen is being lit up by the radiation from a nearby young star.
“This image shows the power of Webb,” said Rebecca Levy, second author of the study, at the University of Arizona in Tucson. “Every single white dot in this image is either a star or a star cluster. We can start to distinguish all of these tiny point sources, which enables us to acquire an accurate count of all the star clusters in this galaxy.”
Looking at M82 in slightly longer infrared wavelengths, clumpy tendrils represented in red can be seen extending above and below the plane of the galaxy. These gaseous streamers are a galactic wind rushing out from the core of the starburst.
One area of focus for this research team was understanding how this galactic wind, which is caused by the rapid rate of star formation and subsequent supernovae, is being launched and influencing its surrounding environment. By resolving a central section of M82, scientists have been able to examine where the wind originates, and gain insight into how hot and cold components interact within the wind.
A team of astronomers used the NASA/ESA/CSA James Webb Space Telescope to survey the starburst galaxy Messier 82 (M82), which is located 12 million light-years away in the constellation Ursa Major. M82 hosts a frenzy of star formation, sprouting new stars 10 times faster than the Milky Way galaxy. Webb’s infrared capabilities enabled scientists to peer through curtains of dust and gas that have historically obscured the star formation process. This image from Webb’s NIRCam (Near-Infrared Camera) instrument shows the centre of M82 with an unprecedented level of detail. With Webb’s resolution, astronomers can distinguish small, bright compact sources that are either individual stars or star clusters. Obtaining an accurate count of the stars and clusters that compose M82’s centre can help astronomers understand the different phases of star formation and the timelines for each stage. In this image, light at 2.12 microns is coloured red, 1.64 microns is green, and 1.40 microns is blue (filters F212N, 164N, and F140M, respectively). Credit: NASA, ESA, CSA, STScI, A. Bolatto (UMD)
Webb’s NIRCam instrument was well suited to tracing the structure of the galactic wind via emission from sooty chemical molecules known as polycyclic aromatic hydrocarbons (PAHs). PAHs can be considered as very small dust grains that survive in cooler temperatures but are destroyed in hot conditions.
Much to the team’s surprise, Webb’s view of the PAH emission highlights the galactic wind’s fine structure — an aspect previously unknown. Depicted as red filaments, the emission extends away from the central region where the heart of star formation is located. Another unanticipated find was the similarity between the structure of the PAH emission and that of the hot, ionised gas.
“It was unexpected to see the PAH emission resemble ionised gas,” said Bolatto. “PAHs are not supposed to live very long when exposed to such a strong radiation field, so perhaps they are being replenished all the time. It challenges our theories and shows us that further investigation is required.”
Webb’s observations of M82 in near-infrared light also spur further questions about star formation, some of which the team hopes to answer with additional data gathered with Webb, including that of another starburst galaxy. Two other papers from this team characterising the stellar clusters and correlations among wind components of M82 are almost finalised.
The starburst galaxy M82 was observed by the NASA/ESA Hubble Space Telescope in 2006, which showed the galaxy’s edge-on spiral disc, shredded clouds, and hot hydrogen gas. The NASA/ESA/CSA James Webb Space Telescope has observed M82’s core, capturing in unprecedented detail the structure of the galactic wind and characterising individual stars and star clusters. The Webb image is from the telescope’s NIRCam (Near-Infrared Camera) instrument. The red filaments trace the shape of the cool component of the galactic wind via polycyclic aromatic hydrocarbons (PAHs). PAHs are very small dust grains that survive in cooler temperatures but are destroyed in hot conditions. The structure of the emission is similar to that of the ionised gas, suggesting PAHs may be replenished from cooler molecular material as it is ionised. Credit: NASA, ESA, CSA, STScI, A. Bolatto (UMD)
In the near future, the team will have spectroscopic observations of M82 from Webb ready for their analysis, as well as complementary large-scale images of the galaxy and its wind. Spectral data will help astronomers determine accurate ages for the star clusters and provide a sense of how long each phase of star formation lasts in a starburst galaxy environment. On a broader scale, inspecting the activity in galaxies like M82 can deepen astronomers’ understanding of the early Universe.
“With these amazing Webb images, and our upcoming spectra, we can study how exactly the strong winds and shock fronts from young stars and supernovae can remove the very gas and dust from which new stars are forming,” said Torsten Böker of the European Space Agency, a co-author of the study. “A detailed understanding of this ‘feedback’ cycle is important for theories of how the early Universe evolved, because compact starbursts such as the one in M82 were very common at high redshift.”
These findings have been accepted for publication in The Astrophysical Journal.
