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Webb finds evidence for a neutron star at heart of SN 1987A, a young supernova remnant

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neutron star SN 1987A A graphic with three images, each of a glowing, ring-shaped nebula. The left side shows a large, full-colour image of the nebula and its surroundings, labelled “NIRCam”. A rectangle in the centre of the nebula is highlighted and two images of this area are pulled out to the right. Both are shown in shades of orange. The top one is labelled “MIRI MRS Argon II” and the bottom one “NIRSpec IFU Argon VI.

Webb finds evidence for a neutron star at heart of SN 1987A, a young supernova remnant

The NASA/ESA/CSA James Webb Space Telescope has found the best evidence yet for emission from a neutron star at the site of SN 1987A, a recently observed supernova. The supernova, known as SN 1987A, occurred 160 000 light-years from Earth in the Large Magellanic Cloud. SN 1987A was a type II supernova [1] that was observed on Earth in 1987, the first supernova that was visible to the naked eye since 1604 — before the advent of telescopes. It has thus offered the astronomical community a rare opportunity to study the evolution of a supernova and what was left behind, from the very beginning. SN 1987A was a core-collapse supernova, meaning the compacted remains at its core are expected to have formed either a neutron star or a black hole. Evidence for such a compact object has long been sought, and whilst indirect evidence for the presence of a neutron star has previously been found, this is the first time that the effects of high energy emission from the young neutron star has been detected.

Astronomy typically involves the study of processes that take place over at least tens of thousands of years: far longer than all of human recorded history. Supernovae — the explosive final death throes of some massive stars — blast out within hours, and the brightness of the explosion peaks within a few months. The remains of the exploding star will continue to evolve at a rapid rate over the following decades. Thus, supernovae offer a very rare opportunity for astronomers to study a key astronomical process in real time. The supernova SN 1987A was first observed on Earth in February 1987 and its brightness peaked in May that year (although its distance from Earth means that the supernova event actually took place about 160 000 years before). It was the first supernova that could be seen with the naked eye since Kepler’s Supernova was observed in 1604.

About two hours prior to the visible observation of SN 1987A, three observatories around the world observed a burst of neutrinos lasting only a few seconds [2]. Shortly after, visible light from SN 1987A was observed. The two different observations were linked to the same supernova event, and provided important evidence to inform the theory of how core-collapse supernovae take place. This theory included the supposition that this type of supernova would form a neutron star or a black hole. Astronomers have searched for evidence for one or other of these compact objects [3] at the centre of the expanding remnant material ever since. Indirect evidence for the presence of a neutron star at the centre of the remnant has been found in the past few years, and observations of much older supernova remnants — such as the Crab Nebula — confirm that neutron stars are found in many supernova remnants. However, no direct evidence of a neutron star in the aftermath of SN 1987A (or any other such recent supernova explosion) had been observed, until now.

Claes Fransson of Stockholm University, and the lead author on this study, explains: “From theoretical models of SN 1987A, the 10-second burst of neutrinos observed just before the supernova implied that a neutron star or black hole was formed in the explosion. But we have not observed any compelling signature of such a newborn object from any supernova explosion. With JWST, we have now found direct evidence for emission triggered by the newborn compact object, most likely a neutron star.”

Webb began science observations in July 2022, and the Webb observations behind this work were taken on 16 July, making the SN 1987A remnant one the first objects observed by Webb. The team used the Medium Resolution Spectrograph (MRS) mode of Webb’s MIRI instrument, which the members of the same team helped to develop. The MRS is a type of instrument known as an Integral Field Unit (IFU). IFUs are fascinating instruments that are able to image an object and take a spectrum of it at the same time. An IFU forms a spectrum at each pixel, allowing observers to see spectroscopic differences across the object. Analysis of the Doppler shift [4] of each spectrum also permits the evaluation of the velocity at each position. Spectral analysis of the results showed a strong signal due to ionised argon from the centre of the ejected material that surrounds the original site of SN 1987A. Subsequent observations using the other IFU, NIRSpec (Near Infrared Spectrograph) at shorter wavelengths, the team found even more heavily ionised [5] chemical species, particularly five times ionised argon (meaning argon atoms that have lost five of their 18 electrons). Such ions require highly energetic photons to form, and those photons have to come from somewhere.

“To create these ions that we observed in the ejecta, it was clear that there had to be a source of high-energy radiation in the centre of the SN 1987A remnant,” Fransson said. “In the paper we discuss different possibilities, finding that only a few scenarios are likely, and all of these involve a newly born neutron star.” 

More observations are planned this year, with Webb and ground-based telescopes. The research team hopes ongoing study will provide more clarity about exactly what is happening in the heart of the SN 1987A remnant. These observations will hopefully stimulate the development of more detailed models [6], ultimately enabling astronomers to better understand not just SN 1987A, but all core-collapse supernovae.

A graphic with three images, each of a glowing, ring-shaped nebula. The left side shows a large, full-colour image of the nebula and its surroundings, labelled “NIRCam”. A rectangle in the centre of the nebula is highlighted and two images of this area are pulled out to the right. Both are shown in shades of orange. The top one is labelled “MIRI MRS Argon II” and the bottom one “NIRSpec IFU Argon VI.
The NASA/ESA/CSA James Webb Space Telescope has observed the best evidence yet for emission from a neutron star at the site of 1987A, a well-known and recently-observed supernova. The supernova, known as SN 1987A, occurred 160 000 light-years from Earth in the Large Magellanic Cloud.
LEFT: Webb’s 2023 NIRCam (Near-Infrared Camera) image of SN 1987A that highlights the object’s central structure, expanding with several thousands km/s. The blue region is the densest part of the clumpy ejecta, containing heavy elements like carbon, oxygen, magnesium and iron, as well as dust. The bright ‘ring of pearls’ is the result of the collision of the ejecta with a ring of gas ejected about 20 000 years before the explosion. Now spots are found even exterior to the ring, with diffuse emission surrounding it. These are the locations of supernova shocks hitting more exterior material from the progenitor star. The outer ejecta is now illuminated by X-rays from the collision, while the inner ejecta is powered mainly by radioactivity and a putative compact object.
RIGHT: An international team of astronomers has now used two of Webb’s instruments to study the emissions from the core of SN 1987A. The top image features the data from Webb’s MRS (Medium Resolution Spectrograph) mode of the MIRI instrument (Mid-InfraRed Instrument). The bottom image depicts data from Webb’s NIRSpec (Near Infrared Spectrograph) at shorter wavelengths. Spectral analysis of the MIRI results showed a strong signal due to ionised argon from the centre of the ejected material that surrounds the original site of SN 1987A. The NIRSpec data found even more heavily ionised chemical species, particularly five times ionised argon (meaning argon atoms that have lost five of their 18 electrons). Weak lines of ionised sulphur were also detected with MIRI. This indicated to the science team that there is a source of high-energy radiation in the centre of the SN 1987A remnant, illuminating an almost point-like region in the centre. The most likely source is believed to be a newly born neutron star.
Credit: NASA, ESA, CSA, STScI, and C. Fransson (Stockholm University), M. Matsuura (Cardiff University), M. J. Barlow (University College London), P. J. Kavanagh (Maynooth University), J. Larsson (KTH Royal Institute of Technology)

Notes

[1] Type II supernovae are distinguishable from Type Ia supernovae by the presence of hydrogen in their spectra. They typically result from the core-collapse of a dying massive star with 8–25 times the mass of our Sun. Core-collapse supernovae derive their energy from gravitational potential energy and create and release far more neutrinos than the other mechanism that causes supernovae (nuclear runaway in certain binary star systems). About 99.6 % of the energy is released as neutrinos, while most the rest comes out as kinetic energy and only a tiny fraction as light. Still, they can be as bright as whole galaxy.

[2] Neutrinos are a chargeless type of subatomic particle. They are extremely low in mass (about 500 000 times less massive than an electron). They interact very weakly with other matter, making them extremely challenging to detect. They are produced in abundance in core-collapse supernovae, hence the association between the observed blast of neutrinos and SN 1987A.

[3] Compact objects in astronomy are extremely dense stellar remnants, including white dwarfs, neutron stars and black holes. The core of a neutron star is so dense that a single teaspoon of the neutron material there would weigh over three billion tons.

[4] The Doppler shift of light occurs when light is stretched or compressed, either due to the velocity of a light source relative to an observer, or due to the expansion or compression of spacetime itself. In this case, the light from the supernova is notably Doppler shifted by the very high velocities of the ejecta from the supernova explosion.

[5] Ionisation occurs when an atom or a molecule gains or loses electrons, giving it an overall electric charge. This typically happens as a result of either collisions with other particles, or the presence of so-called ionising radiation, such as X-rays and some ultraviolet radiation.

[6] Models are simplified theoretical representations of the behaviour of objects or systems, that allow scientists to predict and explain observations. They might be built on mathematical, chemical and physical principles. In astronomy, as with all sciences, both models and observations are used to develop and refine our understanding of how things work.

 

Press release from ESA Webb.

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Webb depicts staggering structure in 19 nearby spiral galaxies

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19 Nineteen Webb images of face-on spiral galaxies are combined in a mosaic, some within squares, and others horizontal or vertical rectangles. Galaxies’ spiral arms appear in shades of orange, and many of their centres have light blue hazes.

Webb depicts staggering structure in 19 nearby spiral galaxies

A new treasure trove of images from the NASA/ESA/CSA James Webb Space Telescope showcases near- and mid-infrared portraits of 19 face-on spiral galaxies. This new set of exquisite images show stars, gas, and dust on the smallest scales ever observed beyond our own galaxy. Teams of researchers are studying these images to uncover the origins of these intricate structures. The research community’s collective analysis will ultimately inform theorists’ simulations, and advance our understanding of star formation and the evolution of spiral galaxies.

19 Nineteen Webb images of face-on spiral galaxies are combined in a mosaic, some within squares, and others horizontal or vertical rectangles. Galaxies’ spiral arms appear in shades of orange, and many of their centres have light blue hazes.
This collection of 19 face-on spiral galaxies from the NASA/ESA/CSA James Webb Space Telescope in near- and mid-infrared light is at once overwhelming and awe-inspiring. Webb’s NIRCam (Near-Infrared Camera) captured millions of stars in these images. Older stars appear blue here, and are clustered at the galaxies’ cores. The telescope’s MIRI (Mid-Infrared Instrument) observations highlight glowing dust, showing where it exists around and between stars – appearing in shades of red and orange. Stars that haven’t yet fully formed and are encased in gas and dust appear bright red.
Webb’s high-resolution images are the first to show large, spherical shells in the gas and dust in such exquisite detail. These holes may have been created by stars that exploded and carved out giant regions in the interstellar material.
Another eye-catching detail? Several galaxy cores are awash in pink-and-red diffraction spikes. These are clear signs that these galaxies may have central active supermassive black holes or central star clusters.
These spiral galaxies are Webb’s first big batch of contributions to the Physics at High Angular resolution in Nearby GalaxieS (PHANGS) program, that includes existing images and data from the NASA/ESA Hubble Space Telescope, the Very Large Telescope’s Multi-Unit Spectroscopic Explorer (MUSE), and the Atacama Large Millimetre/submillimetre Array (ALMA). With Webb’s images, researchers can now examine these galaxies in ultraviolet, visible, infrared, and radio light.
Credit: NASA, ESA, CSA, STScI, J. Lee (STScI), T. Williams (Oxford), PHANGS Team, E. Wheatley (STScI)

If you follow each of the galaxy’s clearly defined arms, which are brimming with stars, to their centres, there may be old star clusters and – sometimes – active supermassive black holes. Only the James Webb Space Telescope can deliver highly detailed scenes of nearby galaxies in a combination of near- and mid-infrared light – and a set of these images were publicly released today.

These Webb images are part of a large, long-standing project, the Physics at High Angular resolution in Nearby GalaxieS (PHANGS) programme, which is supported by more than 150 astronomers worldwide. Before Webb took these images, PHANGS was already brimming with data from the NASA/ESA Hubble Space Telescope, the Very Large Telescope’s Multi-Unit Spectroscopic Explorer, and the Atacama Large Millimetre/submillimetre Array, including observations in ultraviolet, visible, and radio light. Webb’s near- and mid-infrared contributions have provided several new puzzle pieces.

Webb’s NIRCam (Near-Infrared Camera) captured millions of stars in these images, which sparkle in blue tones. Some stars are spread throughout the spiral arms, but others are clumped tightly together in star clusters.

The telescope’s MIRI (Mid-Infrared Instrument) data highlights glowing dust, showing us where it exists behind, around, and between stars. It also spotlights stars that haven’t yet fully formed – they are still encased in the gas and dust that feed their growth, like bright red seeds at the tips of dusty peaks.

To the amazement of astronomers, Webb’s images also show large, spherical shells in the gas and dust that may have been created by exploded stars.

The spiral arms’ extended regions of gas also reveal details in red and orange. Astronomers study the spacing of these features to learn how a galaxy distributes its gas and dust. These structures will provide key insights about how galaxies build, maintain, and shut off star formation.

Evidence shows that galaxies grow from inside out – star formation begins at galaxies’ cores and spreads along their arms, spiralling away from the centre. The farther a star is from the galaxy’s core, the more likely it is to be younger. In contrast, the areas near the cores that look lit by a blue spotlight are populations of older stars. The galaxy cores that are awash in pink-and-red diffraction spikes may indicate an active supermassive black hole or saturation from bright star clusters toward the centre.

There are many avenues of research that scientists can begin to pursue with the combined PHANGS data, but the unprecedented number of stars Webb resolved are a great place to begin. In addition to immediately releasing these images, the PHANGS team has also released the largest catalogue to date of roughly 100 000 star clusters.

 

Press release from ESA Webb.

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Webb discovers dusty cat’s tail in Beta Pictoris System

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A wide, thin horizontal orange line appears at the centre, extending almost to the edges, a debris disc seen edge-on. A thin blue-green disc is inclined about five degrees counterclockwise relative to the main orange disc. Cloudy, translucent grey material is most prominent near the orange main debris disc. Some of the grey material forms a curved feature in the upper right, resembling a cat’s tail. At the centre is a black circle with a bar. The central star, represented as a small white star icon, is blocked by an instrument known as a coronagraph. The background of space is black.

Webb discovers dusty cat’s tail in Beta Pictoris System

Beta Pictoris, a young planetary system located just 63 light-years away, continues to intrigue scientists even after decades of in-depth study. It possesses the first dust disc imaged around another star — a disc of debris produced by collisions between asteroids, comets, and planetesimals. Observations from the NASA/ESA Hubble Space Telescope revealed a second debris disc in this system [1], inclined with respect to the first. Now, a team of astronomers using the NASA/ESA/CSA James Webb Space Telescope to image the Beta Pictoris (Beta Pic) system has discovered a new, previously unseen structure.

A wide, thin horizontal orange line appears at the centre, extending almost to the edges, a debris disc seen edge-on. A thin blue-green disc is inclined about five degrees counterclockwise relative to the main orange disc. Cloudy, translucent grey material is most prominent near the orange main debris disc. Some of the grey material forms a curved feature in the upper right, resembling a cat’s tail. At the centre is a black circle with a bar. The central star, represented as a small white star icon, is blocked by an instrument known as a coronagraph. The background of space is black.
This image from Webb’s MIRI (Mid-Infrared Instrument) shows the star system Beta Pictoris. An edge-on disc of dusty debris generated by collisions between planetesimals (orange) dominates the view. A hotter, secondary disc (cyan) is inclined by about 5 degrees relative to the primary disc. The curved feature at upper right, which the science team nicknamed the “cat’s tail,” has never been seen before. A coronagraph (black circle and bar) has been used to block the light of the central star, whose location is marked with a white star shape. In this image light at 15.5 microns is coloured cyan and 23 microns is orange (filters F1550C and F2300C, respectively).
Credit: NASA, ESA, CSA, STScI, C. Stark and K. Lawson (NASA GSFC), J. Kammerer (ESO), and M. Perrin (STScI)

The team, led by Isabel Rebollido of the Astrobiology Center in Spain, and now an ESA Research Fellow, used Webb’s NIRCam (Near-Infrared Camera) and MIRI (Mid-Infrared Instrument) to investigate the composition of Beta Pic’s previously detected main and secondary debris discs. The results exceeded their expectations, revealing a sharply inclined branch of dust, shaped like a cat’s tail, that extends from the southwest portion of the secondary debris disc.

“Beta Pictoris is the debris disc that has it all: It has a really bright, close star that we can study very well,” said Rebollido. “While there have been previous observations from the ground in this wavelength range, they did not have the sensitivity and the spatial resolution that we now have with Webb, so they didn’t detect this feature.”

A wide, thin horizontal orange line appears at the centre, extending almost to the edges, a debris disc seen edge-on. A thin blue-green disc is inclined about five degrees counterclockwise relative to the main orange disc. Cloudy, translucent grey material is most prominent near the orange main debris disc. Some of the grey material forms a curved feature in the upper right, resembling a cat’s tail. At the centre is a black circle with a bar. The central star, represented as a small white star icon, is blocked by an instrument known as a coronagraph. The background of space is black.
This image from Webb’s MIRI (Mid-Infrared Instrument) shows the star system Beta Pictoris. An edge-on disc of dusty debris generated by collisions between planetesimals (orange) dominates the view. A hotter, secondary disc (cyan) is inclined by about 5 degrees relative to the primary disc. The curved feature at upper right, which the science team nicknamed the “cat’s tail,” has never been seen before. A coronagraph (black circle and bar) has been used to block the light of the central star, whose location is marked with a white star shape. In this image light at 15.5 microns is coloured cyan and 23 microns is orange (filters F1550C and F2300C, respectively).
Credit:
NASA, ESA, CSA, STScI, C. Stark and K. Lawson (NASA GSFC), J. Kammerer (ESO), and M. Perrin (STScI)

A Star’s Portrait Improved with Webb

Even with Webb, peering at Beta Pic in the right wavelength range — in this case, the mid-infrared — was crucial to detect the cat’s tail, as it only appeared in the MIRI data. Webb’s mid-infrared data also revealed differences in temperature between Beta Pic’s two discs, which likely is due to differences in composition.

“We didn’t expect Webb to reveal that there are two different types of material around Beta Pic, but MIRI clearly showed us that the material of the secondary disc and cat’s tail is hotter than the main disc,” said Christopher Stark, a co-author of the study at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “The dust that forms that disc and tail must be very dark, so we don’t easily see it at visible or near-infrared wavelengths — but in the mid-infrared, it’s glowing.”

To explain the hotter temperature, the team deduced that the dust may be highly porous “organic refractory material,” similar to the matter found on the surfaces of comets and asteroids in our solar system. For example, a preliminary analysis of material sampled from asteroid Bennu by NASA’s OSIRIS-Rex mission found it to be very dark and carbon-rich, much like what MIRI detected at Beta Pic.

The Tail’s Puzzling Beginning Warrants Future Research

However, a major lingering question remains: What could explain the shape of the cat’s tail, a uniquely curved feature unlike what is seen in discs around other stars?

Rebollido and the team modelled various scenarios in an attempt to emulate the cat’s tail and unravel its origins. Though further research and testing is required, the team presents a strong hypothesis that the cat’s tail is the result of a dust production event that occurred a mere one hundred years ago.

“Something happens — like a collision — and a lot of dust is produced,” shared Marshall Perrin, a co-author of the study at the Space Telescope Science Institute in Baltimore, Maryland. “At first, the dust goes in the same orbital direction as its source, but then it also starts to spread out. The light from the star pushes the smallest, fluffiest dust particles away from the star faster, while the bigger grains do not move as much, creating a long tendril of dust.”

“The cat’s tail feature is highly unusual, and reproducing the curvature with a dynamical model was difficult,” explained Stark. “Our model requires dust that can be pushed out of the system extremely rapidly, which again suggests it’s made of organic refractory material.”

The team’s preferred model explains the sharp angle of the tail away from the disc as a simple optical illusion. Our perspective combined with the curved shape of the tail creates the observed angle of the tail, while in fact, the arc of material is only departing from the disc at a five-degree incline. Taking into consideration the tail’s brightness, the team estimates the amount of dust within the cat’s tail to be equivalent to a large main belt asteroid spread out across 16 billion kilometres.

A recent dust production event within Beta Pic’s debris discs could also explain an asymmetry previously spotted by the Atacama Large Millimeter/submillimeter Array in 2014: a clump of carbon monoxide (CO) located near the cat’s tail. Since the star’s radiation should break down CO within roughly one hundred years, this still-present concentration of gas could be lingering evidence of the same event.

“Our research suggests that Beta Pic may be even more active and chaotic than we had previously thought,” said Stark. “Webb continues to surprise us, even when looking at the most well-studied objects. We have a completely new window into these planetary systems.”

These results were presented in a press conference at the 243rd meeting of the American Astronomical Society in New Orleans, Louisiana.

The observations were taken as part of Guaranteed Time Observation program 1411.

Notes

[1] Learn more about these 2006 Hubble observations that revealed a second debris disc in the Beta Pic system here.

A wide, thin horizontal orange line appears at the centre, extending almost to the edges, a debris disc seen edge-on. A thin blue-green disc is inclined about five degrees counterclockwise relative to the main orange disc. Cloudy, translucent grey material is most prominent near the orange main debris disc. Some of the grey material forms a curved feature in the upper right, resembling a cat’s tail. At the centre is a black circle with a bar. The central star, represented as a small white star icon, is blocked by an instrument known as a coronagraph. The background of space is black.
This image from Webb’s MIRI (Mid-Infrared Instrument) shows the star system Beta Pictoris. An edge-on disc of dusty debris generated by collisions between planetesimals (orange) dominates the view. A hotter, secondary disc (cyan) is inclined by about 5 degrees relative to the primary disc. The curved feature at upper right, which the science team nicknamed the “cat’s tail,” has never been seen before. A coronagraph (black circle and bar) has been used to block the light of the central star, whose location is marked with a white star shape. In this image light at 15.5 microns is coloured cyan and 23 microns is orange (filters F1550C and F2300C, respectively).
Credit: NASA, ESA, CSA, STScI, C. Stark and K. Lawson (NASA GSFC), J. Kammerer (ESO), and M. Perrin (STScI)

 

Press release from ESA Webb.

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Webb’s new high-definition look at Cassiopeia A supernova remnant

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The image is split into five boxes. A large image at the left-hand side takes up most of the image. There are four images along the right-hand side in a column, which show zoomed-in areas of the larger square image on the left. The image on the left shows a roughly circular cloud of gas and dust with a complex structure, with an inner shell of bright pink and orange filaments that look like tiny pieces of shattered glass. A zoom-in of this material appears in the box labelled 1. Around the exterior of the inner shell in the main image there are wispy curtains of gas that look like campfire smoke. Box 2 is a zoom-in on these circles. Scattered outside the nebula in the main image are clumps of dust, coloured yellow in the image. Boxes 3 and 4 are zoomed-in areas of these clumps. Box 4 highlights a particularly large clump at the bottom right of the main image that is detailed and striated.

Researchers stunned by Webb’s new high-definition look at an exploded star, the Cassiopeia A supernova remnant

Like a shiny, round ornament ready to be placed in the perfect spot on the holiday tree, supernova remnant Cassiopeia A (Cas A) gleams in a new image from the NASA/ESA/CSA James Webb Space Telescope. However, this scene is no proverbial silent night — all is not calm.

A roughly circular cloud of gas and dust with complex structure. The inner shell is made of bright pink and orange filaments studded with clumps and knots that look like tiny pieces of shattered glass. Around the exterior of the inner shell, there are curtains of wispy gas that look like campfire smoke. Around and within the nebula, various stars are seen as points of blue and white light. Outside the nebula, there are also clumps of dust, coloured yellow in the image.
A new high-definition image from the NASA/ESA/CSA James Webb Space Telescope’s NIRCam (Near-Infrared Camera) unveils intricate details of supernova remnant Cassiopeia A (Cas A), and shows the expanding shell of material slamming into the gas shed by the star before it exploded.
The most noticeable colours in Webb’s newest image are clumps of bright orange and light pink that make up the inner shell of the supernova remnant. These tiny knots of gas, composed of sulphur, oxygen, argon, and neon from the star itself, are only detectable thanks to NIRCam’s exquisite resolution, and give researchers a hint at how the dying star shattered like glass when it exploded.
The outskirts of the main inner shell look like smoke from a campfire. This marks where ejected material from the exploded star is ramming into surrounding circumstellar material. Researchers have concluded that this white colour is light from synchrotron radiation, which is generated by charged particles travelling at extremely high speeds and spiralling around magnetic field lines.
There are also several light echoes visible in this image, most notably in the bottom right corner. This is where light from the star’s long-ago explosion has reached, and is warming, distant dust, which glows as it cools down.
Credit: NASA, ESA, CSA, STScI, D. Milisavljevic (Purdue University), T. Temim (Princeton University), I. De Looze (University of Gent)

Webb’s NIRCam (Near-Infrared Camera) view of Cas A displays a very violent explosion at a resolution previously unreachable at these wavelengths. This high-resolution look unveils intricate details of the expanding shell of material slamming into the gas shed by the star before it exploded.

Cas A is one of the best-studied supernova remnants in all the cosmos. Over the years, ground-based and space-based observatories, including the NASA/ESA Hubble Space Telescope, have collectively assembled a multiwavelength picture of the object’s tattered remains.

However, astronomers have now entered a new era in the study of Cas A. In April 2023, Webb’s MIRI (Mid-Infrared Instrument) started this story, revealing new and unexpected features within the inner shell of the supernova remnant. But many of those features are invisible in the new NIRCam image, and astronomers are investigating why that is.

The image is split into five boxes. A large image at the left-hand side takes up most of the image. There are four images along the right-hand side in a column, which show zoomed-in areas of the larger square image on the left. The image on the left shows a roughly circular cloud of gas and dust with a complex structure, with an inner shell of bright pink and orange filaments that look like tiny pieces of shattered glass. A zoom-in of this material appears in the box labelled 1. Around the exterior of the inner shell in the main image there are wispy curtains of gas that look like campfire smoke. Box 2 is a zoom-in on these circles. Scattered outside the nebula in the main image are clumps of dust, coloured yellow in the image. Boxes 3 and 4 are zoomed-in areas of these clumps. Box 4 highlights a particularly large clump at the bottom right of the main image that is detailed and striated.
This image highlights several interesting features of the supernova remnant Cassiopeia A (Cas A), as seen with Webb’s NIRCam (Near-Infrared Camera).
NIRCam’s exquisite resolution is able to detect tiny knots of gas, composed of sulphur, oxygen, argon, and neon from the star itself. Some filaments of debris are too tiny to be resolved, even by Webb, meaning that they are comparable to or less than 16 billion kilometres across (around 100 astronomical units). Researchers consider that this represents how the star shattered like glass when it exploded.
Circular holes visible in the MIRI image within the Green Monster, a loop of green light in Cas A’s inner cavity, are faintly outlined in white and purple emission in the NIRCam image — this represents ionised gas. Researchers believe this is due to the supernova debris pushing through and sculpting gas left behind by the star before it exploded.
This is one of a few light echoes visible in NIRCam’s image of Cas A. A light echo occurs when light from the star’s long-ago explosion has reached, and is warming, distant dust, which glows as it cools down.
NIRCam captured a particularly intricate and large light echo, nicknamed Baby Cas A by researchers. It is actually located about 170 light-years behind the supernova remnant.
Credit: NASA, ESA, CSA, STScI, D. Milisavljevic (Purdue University), T. Temim (Princeton University), I. De Looze (University of Gent)

Infrared light is invisible to our eyes, so image processors and scientists represent these wavelengths of light with visible colours. In this newest image of Cas A, colours were assigned to NIRCam’s different filters, and each of those colours hints at different activity occurring within the object.

At first glance, the NIRCam image may appear less colourful than the MIRI image. However, this does not mean there is less information: it simply comes down to the wavelengths in which the material in the object is emitting its light.

A comparison between two images, one on the left (labelled NIRCam), and on the right (labelled MIRI), separated by a white line. On the left, the image is of a roughly circular cloud of gas and dust with a complex structure. The inner shell is made of bright pink and orange filaments that look like tiny pieces of shattered glass. Around the exterior of the inner shell are curtains of wispy gas that look like campfire smoke. On the right is the same nebula seen in different light. The curtains of material outside the inner shell glow orange instead of white. The inner shell looks more mottled, and is a muted pink. At centre right, a greenish loop extends from the right side of the ring into the central cavity.
This image provides a side-by-side comparison of supernova remnant Cassiopeia A (Cas A) as captured by the NASA/ESA/CSA James Webb Space Telescope’s NIRCam (Near-Infrared Camera) and MIRI (Mid-Infrared Instrument).
At first glance, Webb’s NIRCam image appears less colourful than the MIRI image. But this is only because the material from the object is emitting light at many different wavelengths The NIRCam image appears a bit sharper than the MIRI image because of its greater resolution.
The outskirts of the main inner shell, which appeared as a deep orange and red in the MIRI image, look like smoke from a campfire in the NIRCam image. This marks where the supernova blast wave is ramming into surrounding circumstellar material. The dust in the circumstellar material is too cool to be detected directly at near-infrared wavelengths, but lights up in the mid-infrared.
Also not seen in the near-infrared view is the loop of green light in the central cavity of Cas A that glowed in mid-infrared light, nicknamed the Green Monster by the research team. The circular holes visible in the MIRI image within the Green Monster, however, are faintly outlined in white and purple emission in the NIRCam image.
Credit: NASA, ESA, CSA, STScI, D. Milisavljevic (Purdue University), T. Temim (Princeton University), I. De Looze (University of Gent)

The most noticeable colours in Webb’s newest image are clumps of bright orange and light pink that make up the inner shell of the supernova remnant. Webb’s razor-sharp view can detect the tiniest knots of gas, composed of sulphur, oxygen, argon, and neon from the star itself. Embedded in this gas is a mixture of dust and molecules, which will eventually be incorporated into new stars and planetary systems. Some filaments of debris are too tiny to be resolved, even by Webb, meaning that they are comparable to or less than 16 billion kilometres across (around 100 astronomical units). In comparison, the entirety of Cas A spans 10 light-years, or roughly 96 trillion kilometres.

When comparing Webb’s new near-infrared view of Cas A with the mid-infrared view, its inner cavity and outermost shell are curiously devoid of colour. The outskirts of the main inner shell, which appeared as a deep orange and red in the MIRI image, now look like smoke from a campfire. This marks where the supernova blast wave is ramming into the surrounding circumstellar material. The dust in the circumstellar material is too cool to be detected directly at near-infrared wavelengths, but lights up in the mid-infrared.

Researchers have concluded that the white colour is light from synchrotron radiation, which is emitted across the electromagnetic spectrum, including the near-infrared. It’s generated by charged particles travelling at extremely high speeds and spiralling around magnetic field lines. Synchrotron radiation is also visible in the bubble-like shells in the lower half of the inner cavity.

Also not seen in the near-infrared view is the loop of green light in the central cavity of Cas A that glowed in mid-infrared light, appropriately nicknamed the Green Monster by the research team. This feature was described as ‘challenging to understand’ by researchers at the time of their first look.

While the ‘green’ of the Green Monster is not visible in NIRCam, what’s left over in the near-infrared in that region can provide insight into the mysterious feature. The circular holes visible in the MIRI image are faintly outlined in white and purple emission in the NIRCam image — this represents ionised gas. Researchers believe this is due to the supernova debris pushing through and sculpting gas left behind by the star before it exploded.

Researchers were also absolutely stunned by one fascinating feature at the bottom right corner of NIRCam’s field of view. They’re calling that large, striated blob Baby Cas A — because it appears like an offspring of the main supernova.

This is a light echo. Light from the star’s long-ago explosion has reached, and is warming, distant dust, which glows as it cools down. The intricacy of the dust pattern, and Baby Cas A’s apparent proximity to Cas A itself, are particularly intriguing to researchers. In actuality, Baby Cas A is located about 170 light-years behind the supernova remnant.

There are also several other, smaller light echoes scattered throughout Webb’s new portrait.

The Cas A supernova remnant is located 11 000 light-years away in the constellation Cassiopeia. It’s estimated to have exploded about 340 years ago from our point of view.

The image shows a roughly circular cloud of gas and dust with a complex structure. At lower left, a white arrow pointing in the 2 o’clock direction is labelled N for north, while an arrow pointing in the 10 o‘clock direction is labelled E for east. At lower right, a scale bar is labelled 3 light-years and 1 arcminute. At the bottom is a list of MIRI filters in different colours, from left to right: F162M (blue), F356W (green), and F444W (red).
This image of the Cassiopeia A supernova remnant, captured by Webb’s NIRCam (Near-Infrared Camera) 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.
The scale bar is labeled in light-years, which is the distance that light travels in one Earth-year (it takes 3 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 kilometers.
This image shows invisible near-infrared wavelengths of light that are represented by 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, D. Milisavljevic (Purdue University), T. Temim (Princeton University), I. De Looze (University of Gent)

Press release from ESA Webb.

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The protoplanetary disc XUE 1 shows that rocky planets can form in extreme environments

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At the centre of the image, a bright light source illuminates a surrounding disc, which transitions from colours of white, grey, to orange. The disc is slightly tilted from upper left to lower right, and has spiral features that are most prominent near the star. Small, rocky objects are scattered throughout the disc. At upper right, there is a gap through which background stars can be seen.

The protoplanetary disc XUE 1 shows that rocky planets can form in extreme environments; the study has been published in The Astrophysical Journal

An international team of astronomers have used the NASA/ESA/CSA James Webb Space Telescope to provide the first observation of water and other molecules in the inner, rocky-planet-forming regions of a disc in one of the most extreme environments in our Galaxy. These results suggest that the conditions for rocky-planet formation, typically found in the discs of low-mass star-forming regions, can also occur in massive-star-forming regions and possibly a broader range of environments.

At the centre of the image, a bright light source illuminates a surrounding disc, which transitions from colours of white, grey, to orange. The disc is slightly tilted from upper left to lower right, and has spiral features that are most prominent near the star. Small, rocky objects are scattered throughout the disc. At upper right, there is a gap through which background stars can be seen.
This is an artist’s impression of a young star surrounded by a protoplanetary disc in which planets are forming.
An international team of astronomers have used the NASA/ESA/CSA James Webb Space Telescope to provide the first observation of water and other molecules in the inner, rocky-planet-forming regions of a disc in one of the most extreme environments in our galaxy. These results suggest that the conditions for rocky-planet formation, typically found in the discs of low-mass star-forming regions, can also occur in massive-star-forming regions and possibly a broader range of environments.
Credit: ESO/L. Calçada

These are the first results from the eXtreme UV Environments (XUE) James Webb Space Telescope programme, that focuses on the characterisation of planet-forming disc in massive-star-forming regions. These regions are likely representative of the environment in which most planetary systems formed. Understanding the impact of environment on planet formation is important for scientists to gain insights into the diversity of the observed exoplanet populations.

The XUE programme targets a total of 15 discs in three areas of the Lobster Nebula (also known as NGC 6357), a large emission nebula roughly 5500 light-years away from Earth in the constellation Scorpius. The Lobster Nebula is one of the youngest and closest massive star formation complexes, and is host to some of the most massive stars in our Galaxy. Massive stars are hotter, and therefore emit more ultraviolet (UV) radiation. This can disperse the gas, making the expected disc lifetime as short as a million years. Thanks to Webb, astronomers can now study the effect of UV radiation on the inner rocky-planet-forming regions of protoplanetary discs around stars like our Sun.

“Webb is the only telescope with the spatial resolution and sensitivity to study planet-forming discs in massive-star-forming regions,” said team lead María Claudia Ramírez-Tannus of the Max Planck Institute for Astronomy in Germany.

Astronomers aim to characterise the physical properties and chemical composition of the rocky-planet-forming regions of discs in the Lobster Nebula using Webb’s Medium Resolution Spectrometer (MRS) of the Mid-InfraRed Instrument (MIRI). This first result focuses on the protoplanetary disc termed XUE 1, which is located in the star cluster Pismis 24.

Graphic titled “XUE 1 Irradiated Protoplanetary Disc, MIRI Medium -Resolution Spectroscopy” shows a graph of brightness versus wavelength from 4.95 to 5.15 microns, with carbon monoxide peaks highlighted.
This graphic presents some of the first results from the eXtreme UV Environments (XUE) James Webb Space Telescope programme. These results suggest that the conditions for rocky-planet formation, typically found in the discs of low-mass star-forming regions, can also occur in massive-star-forming regions and possibly a broader range of environments.
Astronomers focussed on rocky-planet-forming regions of discs in the Lobster Nebula using Webb’s Medium Resolution Spectrometer (MRS) of the Mid-InfraRed Instrument (MIRI). This first result focuses on the protoplanetary disc termed XUE 1, which is located in the star cluster Pismis 24.
This graphic features the observed signatures of carbon monoxide spanning 4.95 to 5.15 microns
Credit: NASA, ESA, CSA, STScI, J. Olmsted (STScI), M. C Ramírez-Tannus (Max Planck Institute for Astronomy)
Graphic titled “XUE 1 Irradiated Protoplanetary Disc, MIRI Medium -Resolution Spectroscopy” shows a graph of brightness versus wavelength from 13.3 to 15.5 microns, with acetylene, hydrogen cyanide, water, and carbon dioxide peaks highlighted
This graphic presents some of the first results from the eXtreme UV Environments (XUE) James Webb Space Telescope programme. These results suggest that the conditions for rocky-planet formation, typically found in the discs of low-mass star-forming regions, can also occur in massive-star-forming regions and possibly a broader range of environments.
Astronomers focussed on rocky-planet-forming regions of discs in the Lobster Nebula using Webb’s Medium Resolution Spectrometer (MRS) of the Mid-InfraRed Instrument (MIRI). This first result focuses on the protoplanetary disc termed XUE 1, which is located in the star cluster Pismis 24.
The inner disc around XUE 1 revealed signatures of water (highlighted here in blue and centred around 14.2 microns), as well as acetylene (C2H2, highlighted in green; centred around 13.7 microns), hydrogen cyanide (HCN, highlighted in brown; centred around 14.0 microns), and carbon dioxide (CO2, highlighted in red; centred around 14.95 microns). As indicated, some of the emission detected was weaker than some of the predicted models, which might imply a small outer disc radius.
Credit: NASA, ESA, CSA, STScI, J. Olmsted (STScI), M. C Ramírez-Tannus (Max Planck Institute for Astronomy)

“Only the MIRI wavelength range and spectral resolution allow us to probe the molecular inventory and physical conditions of the warm gas and dust where rocky planets form,” said team member Arjan Bik of Stockholm University in Sweden.

Because of its location near several massive stars in NGC6357, scientists expect XUE 1 to have been constantly exposed to a high ultraviolet radiation field throughout its life. However, in this extreme environment the team still detected a range of molecules that are the building blocks of rocky planets.

“We find that the inner disk around XUE 1 is remarkably similar to those in nearby star-forming regions,” said team member Rens Waters of Radboud University in the Netherlands. “We’ve detected water and other molecules like carbon monoxide, carbon dioxide, hydrogen cyanide and acetylene. However, the emission found was weaker than some models predicted. This might imply a small outer disc radius.”

“We were surprised and excited because this is the first time that these molecules have been detected under such extreme conditions,” added Lars Cuijpers of Radboud University. The team also found small, partially crystalline silicate dust at the disc’s surface. This is considered to be the building blocks of rocky planets.

These results are good news for rocky planet formation, as the science team finds that the conditions in the inner disc resemble those found in the well-studied disks located in nearby star-forming regions, where only low-mass stars form. This suggests that rocky planets can form in a much broader range of environments than previously believed.

The team notes that the remaining observations from the XUE programme are crucial to establishing the commonality of these conditions.

“XUE1 shows us that the conditions to form rocky planets are there, so the next step is to check how common that is,” says Ramírez-Tannus. “We will observe other discs in the same region to determine the frequency with which these conditions can be observed.”

These results have been published in The Astrophysical Journal.

 

Press release from ESA Webb

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The Crab Nebula seen in new light by Webb

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The NASA/ESA/CSA James Webb Space Telescope has gazed at the Crab Nebula in the search for answers about the supernova remnant’s origins. Webb’s NIRCam (Near-Infrared Camera) and MIRI (Mid-Infrared Instrument) have revealed new details in infrared light. Similar to the Hubble optical wavelength image released in 2005, with Webb the remnant appears to consist of a crisp, cage-like structure of fluffy red-orange filaments of gas that trace doubly ionised sulphur (sulphur III). Within the remnant’s interior, yellow-white and green fluffy ridges form large-scale loop-like structures, which represent areas where dust particles reside. The area is composed of translucent, milky material. This material is emitting synchrotron radiation, which is emitted across the electromagnetic spectrum but becomes particularly vibrant thanks to Webb’s sensitivity and spatial resolution. It is generated by particles accelerated to extremely high speeds as they wind around magnetic field lines. The synchrotron radiation can be traced throughout the majority of the Crab Nebula’s interior. Locate the wisps that follow a ripple-like pattern in the middle. In the centre of this ring-like structure is a bright white dot: a rapidly rotating neutron star. Further out from the core, follow the thin white ribbons of the radiation. The curvy wisps are closely grouped together, following different directions that mimic the structure of the pulsar’s magnetic field. Note how certain gas filaments are bluer in colour. These areas contain singly ionised iron (iron II).

The Crab Nebula – in the constellation Taurus – is seen in new light by James Webb Space Telescope as new details are uncovered

Although the Crab Nebula is one of the best-studied supernova remnants, questions about its progenitor, the nature of the explosion that created it still remain unanswered. The NASA/ESA/CSA James Webb Space Telescope is on the case as it sleuths for any clues that remain within the supernova remnant. Webb’s infrared sensitivity and spatial resolution are offering astronomers a more comprehensive understanding of the still-expanding scene.

The NASA/ESA/CSA James Webb Space Telescope has gazed at the Crab Nebula in the search for answers about the supernova remnant’s origins. Webb’s NIRCam (Near-Infrared Camera) and MIRI (Mid-Infrared Instrument) have revealed new details in infrared light.Similar to the Hubble optical wavelength image released in 2005, with Webb the remnant appears to consist of a crisp, cage-like structure of fluffy red-orange filaments of gas that trace doubly ionised sulphur (sulphur III). Within the remnant’s interior, yellow-white and green fluffy ridges form large-scale loop-like structures, which represent areas where dust particles reside. The area is composed of translucent, milky material. This material is emitting synchrotron radiation, which is emitted across the electromagnetic spectrum but becomes particularly vibrant thanks to Webb’s sensitivity and spatial resolution. It is generated by particles accelerated to extremely high speeds as they wind around magnetic field lines. The the synchrotron radiation can be traced throughout the majority of the Crab Nebula’s interior. Locate the wisps that follow a ripple-like pattern in the middle. In the centre of this ring-like structure is a bright white dot: a rapidly rotating neutron star. Further out from the core, follow the thin white ribbons of the radiation. The curvy wisps are closely grouped together, following different directions that mimic the structure of the pulsar’s magnetic field. Note how certain gas filaments are bluer in colour. These areas contain singly ionised iron (iron II). Credit: NASA, ESA, CSA, STScI, T. Temim (Princeton University)
The NASA/ESA/CSA James Webb Space Telescope has gazed at the Crab Nebula in the search for answers about the supernova remnant’s origins. Webb’s NIRCam (Near-Infrared Camera) and MIRI (Mid-Infrared Instrument) have revealed new details in infrared light.
Similar to the Hubble optical wavelength image released in 2005, with Webb the remnant appears to consist of a crisp, cage-like structure of fluffy red-orange filaments of gas that trace doubly ionised sulphur (sulphur III). Within the remnant’s interior, yellow-white and green fluffy ridges form large-scale loop-like structures, which represent areas where dust particles reside.
The area is composed of translucent, milky material. This material is emitting synchrotron radiation, which is emitted across the electromagnetic spectrum but becomes particularly vibrant thanks to Webb’s sensitivity and spatial resolution. It is generated by particles accelerated to extremely high speeds as they wind around magnetic field lines. The the synchrotron radiation can be traced throughout the majority of the Crab Nebula’s interior.
Locate the wisps that follow a ripple-like pattern in the middle. In the centre of this ring-like structure is a bright white dot: a rapidly rotating neutron star. Further out from the core, follow the thin white ribbons of the radiation. The curvy wisps are closely grouped together, following different directions that mimic the structure of the pulsar’s magnetic field. Note how certain gas filaments are bluer in colour. These areas contain singly ionised iron (iron II).
Credit: NASA, ESA, CSA, STScI, T. Temim (Princeton University)

The NASA/ESA/CSA James Webb Space Telescope has gazed at the Crab Nebula, a supernova remnant located 6500 light-years away in the constellation Taurus. Since this energetic event was recorded in 1054 CE by 11th-century astronomers, the Crab Nebula has continued to draw attention and additional study as scientists seek to understand the conditions, behaviour, and after-effects of supernovae by carefully studying this relatively close example.

With Webb’s NIRCam (Near-Infrared Camera) and MIRI (Mid-Infrared Instrument), the game is afoot as new details are uncovered—including the first complete map of dust distribution—in the search for answers about the Crab Nebula’s origins.

The NASA/ESA/CSA James Webb Space Telescope has gazed at the Crab Nebula in the search for answers about the supernova remnant’s origins. Webb’s NIRCam (Near-Infrared Camera) and MIRI (Mid-Infrared Instrument) have revealed new details in infrared light.Similar to the Hubble optical wavelength image released in 2005, with Webb the remnant appears to consist of a crisp, cage-like structure of fluffy red-orange filaments of gas that trace doubly ionised sulphur (sulphur III). Within the remnant’s interior, yellow-white and green fluffy ridges form large-scale loop-like structures, which represent areas where dust particles reside. The area is composed of translucent, milky material. This material is emitting synchrotron radiation, which is emitted across the electromagnetic spectrum but becomes particularly vibrant thanks to Webb’s sensitivity and spatial resolution. It is generated by particles accelerated to extremely high speeds as they wind around magnetic field lines. The synchrotron radiation can be traced throughout the majority of the Crab Nebula’s interior. Locate the wisps that follow a ripple-like pattern in the middle. In the centre of this ring-like structure is a bright white dot: a rapidly rotating neutron star. Further out from the core, follow the thin white ribbons of the radiation. The curvy wisps are closely grouped together, following different directions that mimic the structure of the pulsar’s magnetic field. Note how certain gas filaments are bluer in colour. These areas contain singly ionised iron (iron II).
The NASA/ESA/CSA James Webb Space Telescope has gazed at the Crab Nebula in the search for answers about the supernova remnant’s origins. Webb’s NIRCam (Near-Infrared Camera) and MIRI (Mid-Infrared Instrument) have revealed new details in infrared light.
Similar to the Hubble optical wavelength image released in 2005, with Webb the remnant appears to consist of a crisp, cage-like structure of fluffy red-orange filaments of gas that trace doubly ionised sulphur (sulphur III). Within the remnant’s interior, yellow-white and green fluffy ridges form large-scale loop-like structures, which represent areas where dust particles reside.
The area is composed of translucent, milky material. This material is emitting synchrotron radiation, which is emitted across the electromagnetic spectrum but becomes particularly vibrant thanks to Webb’s sensitivity and spatial resolution. It is generated by particles accelerated to extremely high speeds as they wind around magnetic field lines. The synchrotron radiation can be traced throughout the majority of the Crab Nebula’s interior.
Locate the wisps that follow a ripple-like pattern in the middle. In the centre of this ring-like structure is a bright white dot: a rapidly rotating neutron star. Further out from the core, follow the thin white ribbons of the radiation. The curvy wisps are closely grouped together, following different directions that mimic the structure of the pulsar’s magnetic field. Note how certain gas filaments are bluer in colour. These areas contain singly ionised iron (iron II).
Credit: NASA, ESA, CSA, STScI, T. Temim (Princeton University)

At first glance the general shape of the nebula is reminiscent of the 2005 optical wavelength image from the NASA/ESA Hubble Space Telescope. In Webb’s infrared observation, a crisp, cage-like structure of fluffy gaseous filaments are shown in red and orang. However, in the central regions, emission from dust grains (yellow-white and green) is mapped out by Webb for the first time. The Hubble and Webb images of this object can be contrasted here.

On the left is the 2005 Hubble optical wavelength image of the Crab Nebula. On the right is a new image of the object from the James Webb Space Telescope’s NIRCam (Near-Infrared Camera) and MIRI (Mid-Infrared Instrument) instruments that has revealed new details in infrared light.
In Webb’s infrared observation, a crisp, cage-like structure of fluffy red-orange filaments and knots of dust surround the object’s central area. However, some aspects of the inner workings of the Crab Nebula become more prominent and increase in detail in infrared light. In particular, Webb highlights what is known as synchrotron emission, seen here with a milky smoke-like appearance throughout the majority of the Crab Nebula’s interior.
Credit: NASA, ESA, CSA, STScI, T. Temim (Princeton University)

Additional aspects of the inner workings of the Crab Nebula become more prominent and are seen in greater detail in the infrared light captured by Webb. In particular, Webb highlights what is known as synchrotron radiation: emission produced from charged particles, like electrons, moving around magnetic field lines at relativistic speeds. The radiation appears here as milky smoke-like material throughout the majority of the Crab Nebula’s interior.

This feature is a product of the nebula’s pulsar, a rapidly rotating neutron star. The pulsar’s strong magnetic fields accelerate particles to extremely high speeds and cause them to emit radiation as they wind around magnetic field lines. Though emitted across the electromagnetic spectrum, the synchrotron radiation becomes particularly vibrant in the infrared with Webb’s NIRCam instrument.

To locate the Crab Nebula’s pulsar heart, trace the wisps that follow a circular ripple-like pattern in the middle to the bright white dot in the centre. Further out from the core, follow the thin white ribbons of the radiation. The curvy wisps are closely grouped together, outlining the structure of the pulsar’s magnetic fields, which sculpt and shape the nebula.

At centre left and right, the white material curves sharply inward from the filamentary dust cage’s edges and goes toward the neutron star’s location, as if the waist of the nebula is pinched. This abrupt slimming may be caused by the confinement of the supernova wind’s expansion by a belt of dense gas.

The wind produced by the pulsar heart continues to push the shell of gas and dust outward at a rapid pace. Notice how the filaments tend to be longer toward the upper right side of the nebula, in the same direction the pulsar is moving – not restricted by the belt of gas. Among the remnant’s interior, yellow-white and green mottled filaments form large-scale loop-like structures, which represent areas where dust grains reside.

The search for answers about the Crab Nebula’s past continues as astronomers further analyse the Webb data and consult previous observations of the nebula taken by other telescopes. Scientists will have newer Hubble data to review within the next year or so from the telescope’s reimaging of the supernova remnant. This will mark Hubble’s first look at the Crab Nebula in over 20 years, and will enable astronomers to more accurately compare Webb and Hubble’s findings.

Press release from ESA Webb.

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Webb’s MIRI captures an ethereal view of NGC 346

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NGC 346 (MIRI image)

Webb’s MIRI captures an ethereal view of NGC 346

One of the greatest strengths of the NASA/ESA/CSA James Webb Space Telescope is its ability to give astronomers detailed views of areas where new stars are being born. The latest example, showcased here in a new image from Webb’s Mid-Infrared Instrument (MIRI), is NGC 346 – the brightest and largest star-forming region in the Small Magellanic Cloud.

NGC 346 (MIRI image)
This new infrared image of NGC 346 from the NASA/ESA/CSA James Webb Space Telescope’s Mid-Infrared Instrument (MIRI) traces emission from cool gas and dust. In this image blue represents silicates and sooty chemical molecules known as polycyclic aromatic hydrocarbons, or PAHs. More diffuse red emission shines from warm dust heated by the brightest and most massive stars in the heart of the region. Bright patches and filaments mark areas with abundant numbers of protostars.
This image includes 7.7-micron light shown in blue, 10 microns in cyan, 11.3 microns in green, 15 microns in yellow, and 21 microns in red (770W, 1000W, 1130W, 1500W, and 2100W filters, respectively).
Credit: NASA, ESA, CSA, N. Habel (JPL), P. Kavanagh (Maynooth University)

The Small Magellanic Cloud (SMC) is a satellite galaxy of the Milky Way, visible to the unaided eye in the southern constellation Tucana. This small companion galaxy is more primitive than the Milky Way in that it possesses fewer heavy elements, which are forged in stars through nuclear fusion and supernova explosions, compared to our own galaxy.

Since cosmic dust is formed from heavy elements like silicon and oxygen, scientists expected the SMC to lack significant amounts of dust. However the new MIRI image, as well as a previous image of NGC 346 from Webb’s Near-Infrared Camera released in January, show ample dust within this region.

In this representative-colour image, blue tendrils trace emission from material that includes dusty silicates and sooty chemical molecules known as polycyclic aromatic hydrocarbons, or PAHs. More diffuse red emission shines from warm dust heated by the brightest and most massive stars in the heart of the region. An arc at the centre left may be a reflection of light from the star near the arc’s centre (similar, fainter arcs appear associated with stars at lower left and upper right). Lastly, bright patches and filaments mark areas with abundant numbers of protostars. The research team has detected 1,001 pinpoint sources of light, most of them young stars still embedded in their dusty cocoons.

By combining Webb data in both the near-infrared and mid-infrared, astronomers are able to take a fuller census of the stars and protostars within this dynamic region. The results have implications for our understanding of galaxies that existed billions of years ago, during an era in the universe known as “cosmic noon,” when star formation was at its peak and heavy element concentrations were lower, as seen in the SMC.

This new image taken by Webb’s Mid-Infrared Instrument (MIRI) complements Webb’s view of NGC 346 as seen by the (NIRCam), released in January 2023.

NGC 346 (MIRI image, annotated)
This new infrared image of NGC 346 from the NASA/ESA/CSA James Webb Space Telescope’s Mid-Infrared Instrument (MIRI) traces emission from cool gas and dust. In this image blue represents silicates and sooty chemical molecules known as polycyclic aromatic hydrocarbons, or PAHs. More diffuse red emission shines from warm dust heated by the brightest and most massive stars in the heart of the region. Bright patches and filaments mark areas with abundant numbers of protostars.
This image includes 7.7-micron light shown in blue, 10 microns in cyan, 11.3 microns in green, 15 microns in yellow, and 21 microns in red (770W, 1000W, 1130W, 1500W, and 2100W filters, respectively).
Credit: NASA, ESA, CSA, N. Habel (JPL), P. Kavanagh (Maynooth University)

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NGC 346: Webb Uncovers Star Formation in Cluster’s Dusty Ribbons

 

 

 

Press release from ESA Webb.

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Webb discovers methane, carbon dioxide in atmosphere of K2-18 b

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methane carbon dioxide K2-18 b

Webb discovers methane, carbon dioxide in atmosphere of K2-18 b

A new investigation by an international team of astronomers using data from the NASA/ESA/CSA James Webb Space Telescope into K2-18 b, an exoplanet 8.6 times as massive as Earth, has revealed the presence of carbon-bearing molecules including methane and carbon dioxide. The discovery adds to recent studies suggesting that K2-18 b could be a Hycean exoplanet, one which has the potential to possess a hydrogen-rich atmosphere and a water ocean-covered surface.

methane carbon dioxide K2-18 b
This artist’s concept shows what exoplanet K2-18 b could look like based on science data. K2-18 b, an exoplanet 8.6 times as massive as Earth, orbits the cool dwarf star K2-18 in the habitable zone and lies 120 light-years from Earth. A new investigation with the NASA/ESA/CSA James Webb Space Telescope into K2-18 b has revealed the presence of carbon-bearing molecules including methane and carbon dioxide. The abundance of methane and carbon dioxide, and shortage of ammonia, support the hypothesis that there may be an ocean underneath a hydrogen-rich atmosphere in K2-18 b.
Credit:
NASA, CSA, ESA, J. Olmstead (STScI), N. Madhusudhan (Cambridge University)

The first insight into the atmospheric properties of this habitable-zone exoplanet came from observations with the NASA/ESA Hubble Space Telescope, which prompted further studies that have since changed our understanding of the system.

K2-18 b orbits the cool dwarf star K2-18 in the habitable zone and lies 120 light-years from Earth in the constellation Leo. Exoplanets such as K2-18 b, which have sizes between those of Earth and Neptune, are unlike anything in our Solar System. This lack of equivalent nearby planets means that these ‘sub-Neptunes’ are poorly understood, and the nature of their atmospheres is a matter of active debate among astronomers. Exoplanets such as K2-18 b, which have sizes between those of Earth and Neptune, are unlike anything in our Solar System. This lack of analogous nearby planets means that these ‘sub-Neptunes’ are poorly understood and the nature of their atmospheres is a matter of active debate between astronomers. The suggestion that the sub-Neptune K2-18 b could be a Hycean exoplanet is intriguing, as some astronomers believe that these worlds are promising environments to search for evidence for life on exoplanets.

“Our findings underscore the importance of considering diverse habitable environments in the search for life elsewhere,” 

explained Nikku Madhusudhan, an astronomer at the University of Cambridge and lead author of the paper announcing these results.

“Traditionally, the search for life on exoplanets has focused primarily on smaller rocky planets, but the larger Hycean worlds are significantly more conducive to atmospheric observations.“

The abundance of methane and carbon dioxide, and shortage of ammonia, support the hypothesis that there may be an ocean underneath a hydrogen-rich atmosphere on K2-18 b. These initial Webb observations also provided a possible detection of a molecule called dimethyl sulphide (DMS). On Earth, this is only produced by life. The bulk of the DMS in Earth’s atmosphere is emitted from phytoplankton in marine environments.

The inference of DMS is less robust and requires further validation.

“Upcoming Webb observations should be able to confirm if DMS is indeed present in the atmosphere of K2-18 b at significant levels,” explained Madhusudhan.

While K2-18 b lies in the habitable zone and is now known to harbour carbon-bearing molecules, this does not necessarily mean that the planet can support life. The planet’s large size — with a radius 2.6 times the radius of Earth — means that the planet’s interior likely contains a large mantle of high-pressure ice, like Neptune, but with a thinner hydrogen-rich atmosphere and an ocean surface. Hycean worlds are predicted to have oceans of water. However, it is also possible that the ocean is too hot to be habitable or be liquid.

“Although this kind of planet does not exist in our solar system, sub-Neptunes are the most common type of planet known so far in the galaxy,” explained team member Subhajit Sarkar of Cardiff University. “We have obtained the most detailed spectrum of a habitable-zone sub-Neptune to date, and this allowed us to work out the molecules that exist in its atmosphere.”

Characterising the atmospheres of exoplanets like K2-18 b — meaning identifying their gases and physical conditions — is a very active area in astronomy. However, these planets are outshone — literally — by the glare of their much larger parent stars, which makes exploring exoplanet atmospheres particularly challenging.

The team sidestepped this challenge by analysing light from K2-18 b’s parent star as it passed through the exoplanet’s atmosphere. K2-18 b is a transiting exoplanet, meaning that we can detect a drop in brightness as it passes across the face of its host star. This is how the exoplanet was first discovered. This means that during transits a tiny fraction of starlight will pass through the exoplanet’s atmosphere before reaching telescopes like Webb. The starlight’s passage through the exoplanet atmosphere leaves traces that astronomers can piece together to determine the gases of the exoplanet’s atmosphere.

“This result was only possible because of the extended wavelength range and unprecedented sensitivity of Webb, which enabled robust detection of spectral features with just two transits,” continued Madhusudhan. “For comparison, one transit observation with Webb provided comparable precision to eight observations with Hubble conducted over a few years and in a relatively narrow wavelength range.”

“These results are the product of just two observations of K2-18 b, with many more on the way,” explained team member Savvas Constantinou of the University of Cambridge. “This means our work here is but an early demonstration of what Webb can observe in habitable-zone exoplanets.”

The team now intends to conduct follow-up research with the telescope’s Mid-InfraRed Instrument (MIRI) spectrograph that they hope will further validate their findings and provide new insights into the environmental conditions on K2-18 b.

“Our ultimate goal is the identification of life on a habitable exoplanet, which would transform our understanding of our place in the Universe,” concluded Madhusudhan. “Our findings are a promising step towards a deeper understanding of Hycean worlds in this quest.”

Spectrum of K2-18 b, obtained with Webb’s NIRISS (Near-Infrared Imager and Slitless Spectrograph) and NIRSpec (Near-Infrared Spectrograph), displays an abundance of methane and carbon dioxide in the exoplanet’s atmosphere, as well as a possible detection of a molecule called dimethyl sulfide (DMS). The detection of methane and carbon dioxide, and shortage of ammonia, are consistent with the presence of an ocean underneath a hydrogen-rich atmosphere in K2-18 b. K2-18 b, 8.6 times as massive as Earth, orbits the cool dwarf star K2-18 in the habitable zone and lies 120 light-years from Earth.
Credit:
NASA, CSA, ESA, J. Olmstead (STScI), N. Madhusudhan (Cambridge University)

The team’s results are accepted for publication in The Astrophysical Journal Letters.

Notes

[1] The Habitable Zone is the region around a star where the conditions could potentially be suitable to sustain life on a planet within this region, for example allowing the presence of liquid water on its surface.

Press release from ESA Webb

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Astronomy

Webb detects water vapour in the inner disk of the system PDS 70

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PDS 70

Webb detects water vapour in the inner disk of the system PDS 70, a rocky planet-forming zone

New measurements by the NASA/ESA/CSA James Webb Space Telescope’s Mid-InfraRed Instrument (MIRI) have detected water vapour in the inner disc of the system PDS 70, located 370 light-years away. This is the first detection of water in the terrestrial region of a disc already known to host two or more protoplanets.

PDS 70
This artist concept portrays the star PDS 70 and its inner protoplanetary disc. New measurements from the NASA/ESA/CSA James Webb Space Telescope’s Mid-InfraRed Instrument (MIRI) have indicated the presence of water vapour in the inner disc of the system PDS 70, located 370 light-years away. This is the first detection of water in the terrestrial region of a disc already known to host two or more protoplanets, one of which is shown at upper right.
Credit: NASA, ESA, CSA, J. Olmsted (STScI)

Water is essential for life as we know it. However, scientists debate how it reached the Earth and whether the same processes could seed rocky exoplanets orbiting distant stars. New insights may come from the system PDS 70, which hosts an inner disc and an outer disc that are separated by a gap of eight billion kilometres, within which are two known gas-giant planets. MIRI has detected water vapour in the system’s inner disc at distances of less than 160 million kilometres from the star — the region where rocky, terrestrial planets may be forming (the Earth orbits 150 million kilometres from our Sun).

“We’ve seen water in other discs, but not so close in and in a system where planets are currently assembling. We couldn’t make this type of measurement before Webb,” said lead author Giulia Perotti of the Max Planck Institute for Astronomy (MPIA) in Heidelberg, Germany.

“This discovery is extremely exciting, as it probes the region where rocky planets similar to Earth typically form,”

added MPIA director Thomas Henning, a co-author of the paper. Henning is co-principal investigator of Webb’s MIRI (Mid-InfraRed Instrument), which made the detection, and the principal investigator of the MINDS (MIRI Mid-Infrared Disk Survey) programme that took the data.

A wet environment for forming planets

PDS 70 is a K-type star, cooler than our Sun, and is estimated to be 5.4 million years old. This is relatively old amongst stars with planet-forming discs, which made the discovery of water vapour surprising.

Over time, the gas and dust content of planet-forming discs declines. Either the central star’s radiation and winds remove such material, or the dust grows into larger objects that eventually form planets. As previous studies failed to detect water in the central regions of similarly aged discs, astronomers suspected it might not survive the harsh stellar radiation, leading to a dry environment for the formation of any rocky planets.

Astronomers haven’t yet detected any planets forming within the inner disc of PDS 70. However, they do see the raw materials for building rocky worlds, in the form of silicates. The detection of water vapour implies that if rocky planets are forming there, they will have water available to them from the beginning.

“We find a relatively large amount of small dust grains. Combined with our detection of water vapour, the inner disc is a very exciting place,” said co-author Rens Waters of Radboud University in the Netherlands.

What is the origin of the water?

The discovery raises the question of where the water came from. The MINDS team considered two different scenarios to explain their finding.

One possibility is that water molecules are forming in place, where we detect them, as hydrogen and oxygen atoms combine. A second possibility is that ice-coated dust particles are being transported from the cool outer disc to the hot inner disc, where the water ice sublimates and turns into vapour. Such a transport system would be surprising, since the dust would have to cross the large gap carved out by the two giant planets.

Another question raised by the discovery is how water could survive so close to the star, where the star’s ultraviolet light should break apart any water molecules. Most likely, surrounding material, such as dust and other water molecules, serves as a protective shield. As a result, the water detected near PDS 70 could survive destruction.

Ultimately, the team will use two of Webb’s other instruments, the Near-InfraRed Camera (NIRCam) and the Near-InfraRed Spectrograph (NIRSpec) to study the PDS 70 system in an effort to glean an even greater understanding.

These observations were made as part of Guaranteed Time Observation program 1282. This finding has been published in the journal Nature.

Water in protoplanetary disc of PDS 70 (MIRI emission spectrum)
New measurements from the NASA/ESA/CSA James Webb Space Telescope’s Mid-InfraRed Instrument (MIRI) have indicated the presence of water vapour in the inner disc of the system PDS 70, located 370 light-years away. This is the first detection of water in the terrestrial region of a disc already known to host two or more protoplanets.
This spectrum of the protoplanetary disk of PDS 70, obtained with Webb’s MIRI instrument, displays a number of emission lines from water vapour.
Credit: NASA, ESA, CSA, J. Olmsted (STScI)

Press release from ESA Webb.

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Webb looks for Fomalhaut’s asteroid belt and finds much more

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Webb asteroid belt Fomalhaut’s The NASA/ESA Hubble Space Telescope and ESA's Herschel Space Observatory, as well as the Atacama Large Millimeter/submillimeter Array (ALMA), have previously taken sharp images of the outermost belt. However, none of them found any structure interior to it. [Image description: An orange oval extends from the 1 o’clock to 7 o’clock positions. It features a prominent outer ring, a darker gap, an intermediate ring, a narrower dark gap, and a bright inner disc. At the centre is a ragged black spot indicating a lack of data.] Credit: NASA, ESA, CSA, A. Pagan (STScI), A. Gáspár (University of Arizona)

Webb looks for Fomalhaut’s asteroid belt and finds much more

Astronomers used the NASA/ESA/CSA James Webb Space Telescope to image the warm dust around a nearby young star, Fomalhaut, in order to study the first asteroid belt ever seen outside of our Solar System in infrared light. But to their surprise, they found that the dusty structures are much more complex than the asteroid and Kuiper dust belts of our Solar System. Overall, there are three nested belts extending out to 23 billion kilometres from the star — that’s 150 times the distance of Earth from the Sun. The scale of the outermost belt is roughly twice the scale of our Solar System’s Kuiper Belt of small bodies and cold dust beyond Neptune. The inner belts — which had never been seen before — were revealed by Webb for the first time.

Webb Fomalhaut’s asteroid beltThe NASA/ESA Hubble Space Telescope and ESA's Herschel Space Observatory, as well as the Atacama Large Millimeter/submillimeter Array (ALMA), have previously taken sharp images of the outermost belt. However, none of them found any structure interior to it. [Image description: An orange oval extends from the 1 o’clock to 7 o’clock positions. It features a prominent outer ring, a darker gap, an intermediate ring, a narrower dark gap, and a bright inner disc. At the centre is a ragged black spot indicating a lack of data.] Credit: NASA, ESA, CSA, A. Pagan (STScI), A. Gáspár (University of Arizona)
Webb looks for Fomalhaut’s asteroid belt and finds much more. This image of the dusty debris disc surrounding the young star Fomalhaut is from Webb’s Mid-Infrared Instrument (MIRI). It reveals three nested belts extending out to 23 billion kilometres from the star. The inner belts — which had never been seen before — were revealed by Webb for the first time.
The NASA/ESA Hubble Space Telescope and ESA’s Herschel Space Observatory, as well as the Atacama Large Millimeter/submillimeter Array (ALMA), have previously taken sharp images of the outermost belt. However, none of them found any structure interior to it.
These belts are most likely shaped by the gravitational forces produced by unseen planets. Credit: NASA, ESA, CSA, A. Pagan (STScI), A. Gáspár (University of Arizona)
The belts encircle the young hot star, which can be seen with the naked eye as the brightest star in the southern constellation Piscis Austrinus. The dusty belts are the debris from collisions of larger bodies, analogous to asteroids and comets, and are frequently described as ‘debris discs’. 

“I would describe Fomalhaut as the archetype of debris discs found elsewhere in our galaxy, because it has components similar to those we have in our own planetary system,” said András Gáspár of the University of Arizona in Tucson and lead author of a new paper describing these results. “By looking at the patterns in these rings, we can actually start to make a little sketch of what a planetary system ought to look like — if we could actually take a deep enough picture to see the suspected planets.”

The NASA/ESA Hubble Space Telescope and ESA’s Herschel Space Observatory, as well as the Atacama Large Millimeter/submillimeter Array (ALMA), have previously taken sharp images of the outermost belt. However, none of them found any structure interior to it. The inner belts have been resolved for the first time by Webb in infrared light.

“Where Webb really excels is that we’re able to physically resolve the thermal glow from dust in those inner regions. So you can see inner belts that we could never see before,” said Schuyler Wolff, another member of the team at the University of Arizona.

Hubble, ALMA, and Webb are tag-teaming to assemble a holistic view of the debris discs around a number of stars. “With Hubble and ALMA, we were able to image a bunch of Kuiper Belt analogues, and we’ve learned loads about how outer discs form and evolve,” said Wolff. “But we need Webb to allow us to image a dozen or so asteroid belts elsewhere. We can learn just as much about the inner warm regions of these discs as Hubble and ALMA taught us about the colder outer regions.”

These belts are most likely shaped by the gravitational forces produced by unseen planets. Similarly, inside our Solar System Jupiter corrals the asteroid belt, the inner edge of the Kuiper Belt is sculpted by Neptune, and the outer edge could be shepherded by as-yet-unseen bodies beyond it. As Webb images more systems, we will learn about the configurations of their planets.

Webb looks for Fomalhaut’s asteroid belt and finds much more. This image of the Fomalhaut system, captured by Webb’s Mid-Infrared Instrument (MIRI), shows compass arrows, scale bar, and colour key for reference. Labels indicate the various structures. At right, a great dust cloud is highlighted and pullouts show it in two infrared wavelengths: 23 and 25.5 microns.
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 astronomical units, which is the average distance between Earth and the Sun: 150 million kilometres. The outer ring is about 240 astronomical units in diameter.
This image shows invisible mid-infrared wavelengths of light that have been translated into visible-light colours. The colour key and labels show which MIRI filters were used when collecting the light.
Credit: NASA, ESA, CSA, A. Pagan (STScI), A. Gáspár (University of Arizona)

Fomalhaut’s dust ring was discovered in 1983 in observations made by NASA’s Infrared Astronomical Satellite (IRAS). The existence of the ring has also been inferred from previous and longer-wavelength observations using submillimetre telescopes on Maunakea, Hawai‘i, NASA’s Spitzer Space Telescope, and Caltech’s Submillimeter Observatory.

“The belts around Fomalhaut are kind of a mystery novel: Where are the planets?” said George Rieke, another team member and US science lead for Webb’s Mid-Infrared Instrument (MIRI), which made these observations. “I think it’s not a very big leap to say there’s probably a really interesting planetary system around the star.”

“We definitely didn’t expect the more complex structure with the second intermediate belt and then the broader asteroid belt,” added Wolff. “That structure is very exciting because any time an astronomer sees a gap and rings in a disc, they say, ‘There could be an embedded planet shaping the rings!’”

Webb also imaged what Gáspár dubs ‘the great dust cloud’, which may be evidence for a collision occurring in the outer ring between two protoplanetary bodies. This is a different feature from the suspected planet first seen inside the outer ring by Hubble in 2008. Subsequent Hubble observations showed that by 2014 the object had vanished. A plausible interpretation is that this newly discovered feature, like the earlier one, is an expanding cloud of very fine dust particles from two icy bodies that smashed into each other.

The idea of a protoplanetary disc around a star goes back to the late 1700s when astronomers Immanuel Kant and Pierre-Simon Laplace independently developed the theory that the Sun and planets formed from a rotating gas cloud that collapsed and flattened under gravity. Debris discs develop later, following the formation of planets and dispersal of the primordial gas in the systems. They show that small bodies like asteroids are colliding catastrophically and pulverising their surfaces into huge clouds of dust and other debris. Observations of dust provide unique clues to the structure of an exoplanetary system, reaching down to Earth-sized planets and even asteroids, which are much too small to see individually.

“This very exciting result highlights the unique power of MIRI to study the structures carved by planets in the innermost regions of circumstellar discs,“ adds Gillian Wright, European principal investigator for MIRI and Director of the UK Astronomy Technology Centre (UKATC).

The team’s results are being published in the journal Nature Astronomy.

 

Press release from ESA Webb.

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