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)
Webb images of Epsilon Indi Ab, a cold exoplanet 12 light-years away
An international team of astronomers using the NASA/ESA/CSA James Webb Space Telescope have directly imaged an exoplanet roughly 12 light-years from Earth. While there were hints that the planet existed, it had not been confirmed until Webb imaged it. The planet is one of the coldest exoplanets observed to date.
The planet, known Epsilon Indi Ab, is several times the mass of Jupiter and orbits the K-type star Epsilon Indi A (Eps Ind A), which is around the age of our Sun, but slightly cooler. The team observed Epsilon Indi Ab using the coronagraph on Webb’s MIRI (Mid-Infrared Instrument). Only a few tens of exoplanets have been directly imaged previously by space- and ground-based observatories.
“Our prior observations of this system have been more indirect measurements of the star, which actually allowed us to see ahead of time that there was likely a giant planet in this system tugging on the star,” said team member Caroline Morley of the University of Texas at Austin. “That’s why our team chose this system to observe first with Webb.”
“This discovery is exciting because the planet is quite similar to Jupiter — it is a little warmer and is more massive, but is more similar to Jupiter than any other planet that has been imaged so far,” added lead author Elisabeth Matthews of the Max Planck Institute for Astronomy in Germany.
A Solar System analog
Previously imaged exoplanets tend to be the youngest, hottest exoplanets that are still radiating much of the energy from when they first formed. As planets cool and contract over their lifetime, they become significantly fainter and therefore harder to image.
“Cold planets are very faint, and most of their emission is in the mid-infrared,” explained Matthews. “Webb is ideally suited to conduct mid-infrared imaging, which is extremely hard to do from the ground. We also needed good spatial resolution to separate the planet and the star in our images, and the large Webb mirror is extremely helpful in this aspect.”
Epsilon Indi Ab is one of the coldest exoplanets to be directly detected, with an estimated temperature of 2 degrees Celsius — colder than any other imaged planet beyond our Solar System, and colder than all but one free-floating brown dwarf [1]. The planet is only around 100 degrees Celsius warmer than gas giants in our Solar System. This provides a rare opportunity for astronomers to study the atmospheric composition of true solar system analogs.
“Astronomers have been imagining planets in this system for decades; fictional planets orbiting Epsilon Indi have been the sites of Star Trek episodes, novels, and video games like Halo,” added Morley. “It’s exciting to actually see a planet there ourselves, and begin to measure its properties.”
Not quite as predicted
Epsilon Indi Ab is the twelfth closest exoplanet to Earth known to date and the closest planet more massive than Jupiter. The science team chose to study Eps Ind A because the system showed hints of a possible planetary body using a technique called radial velocity, which measures the back-and-forth wobbles of the host star along our line of sight.
“While we expected to image a planet in this system, because there were radial velocity indications of its presence, the planet we found isn’t what we had predicted,” shared Matthews. “It’s about twice as massive, a little farther from its star, and has a different orbit than we expected. The cause of this discrepancy remains an open question. The atmosphere of the planet also appears to be a little different than the model predictions. So far we only have a few photometric measurements of the atmosphere, meaning that it is hard to draw conclusions, but the planet is fainter than expected at shorter wavelengths.”
The team believes this may mean there is significant methane, carbon monoxide, and carbon dioxide in the planet’s atmosphere that are absorbing the shorter wavelengths of light. It might also suggest a very cloudy atmosphere.
The direct imaging of exoplanets is particularly valuable for characterization. Scientists can directly collect light from the observed planet and compare its brightness at different wavelengths. So far, the science team has only detected Epsilon Indi Ab at a few wavelengths, but they hope to revisit the planet with Webb to conduct both photometric and spectroscopic observations in the future. They also hope to detect other similar planets with Webb to find possible trends about their atmospheres and how these objects form.
These results were taken with Webb’s Cycle 1 GO programme #2243 and have been published today in Nature.
This image of the gas-giant exoplanet Epsilon Indi Ab was taken with the coronagraph on the NASA/ESA/CSA James Webb Space Telescope’s MIRI (Mid-Infrared Instrument). A star symbol marks the location of the host star Epsilon Indi A, whose light has been blocked by the coronagraph, resulting in the dark circle marked with a dashed white line. Epsilon Indi Ab is one of the coldest exoplanets ever directly imaged. Light at 10.6 microns was assigned the color blue, while light at 15.5 microns was assigned the color orange. MIRI did not resolve the planet, which is a point source. Credit: ESA/Webb, NASA, CSA, STScI, E. Matthews (Max Planck Institute for Astronomy)
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
An international team of astronomers have used the NASA/ESA/CSA James Webb Space Telescope to discover gravitationally bound star clusters when the Universe was 460 million years old. This is the first discovery of star clusters in an infant galaxy less than 500 million years after the Big bang.
An international team of astronomers have used the NASA/ESA/CSA James Webb Space Telescope to discover gravitationally bound star clusters when the Universe was 460 million years old. This is the first discovery of star clusters in an infant galaxy less than 500 million years after the Big bang. Young galaxies in the early Universe underwent significant burst phases of star formation, generating substantial amounts of ionising radiation. However, because of their cosmological distances, direct studies of their stellar content have proven challenging. Using Webb, an international team of astronomers have now detected five young massive star clusters in the Cosmic Gems arc (SPT0615-JD1), a strongly-lensed galaxy emitting light when the Universe was roughly 460 million years old, looking back across 97% of cosmic time. The Cosmic Gems arc was initially discovered in NASA/ESA Hubble Space Telescope images obtained by the RELICS (Reionization Lensing Cluster Survey) programme of the lensing galaxy cluster SPT-CL J0615−5746. With Webb, the science team can now see where stars formed and how they are distributed, in a similar way to how the Hubble Space Telescope is used to study local galaxies. Webb’s view provides a unique opportunity to study star formation and the inner workings of infant galaxies at such an unprecedented distance. Credit: ESA/Webb, NASA & CSA, L. Bradley (STScI), A. Adamo (Stockholm University) and the Cosmic Spring collaboration
Young galaxies in the early Universe underwent significant burst phases of star formation, generating substantial amounts of ionising radiation. However, because of their cosmological distances, direct studies of their stellar content have proven challenging. Using Webb, an international team of astronomers have now detected five young massive star clusters in the Cosmic Gems arc (SPT0615-JD1), a strongly-lensed galaxy emitting light when the Universe was roughly 460 million years old, looking back across 97% of cosmic time.
The Cosmic Gems arc was initially discovered in NASA/ESA Hubble Space Telescope images obtained by the RELICS (Reionization Lensing Cluster Survey) programme of the lensing galaxy cluster SPT-CL J0615−5746.
“These galaxies are thought to be a prime source of the intense radiation that reionised the early Universe,” shared lead author Angela Adamo of Stockholm University and the Oskar Klein Centre in Sweden. “What is special about the Cosmic Gems arc is that thanks togravitational lensingwe can actually resolve the galaxy down to parsec scales!”
An international team of astronomers have used the NASA/ESA/CSA James Webb Space Telescope to discover gravitationally bound star clusters when the Universe was 460 million years old. This is the first discovery of star clusters in an infant galaxy less than 500 million years after the Big bang. Young galaxies in the early Universe underwent significant burst phases of star formation, generating substantial amounts of ionising radiation. However, because of their cosmological distances, direct studies of their stellar content have proven challenging. Using Webb, an international team of astronomers have now detected five young massive star clusters in the Cosmic Gems arc (SPT0615-JD1), a strongly-lensed galaxy emitting light when the Universe was roughly 460 million years old, looking back across 97% of cosmic time. The Cosmic Gems arc was initially discovered in NASA/ESA Hubble Space Telescope images obtained by the RELICS (Reionization Lensing Cluster Survey) programme of the lensing galaxy cluster SPT-CL J0615−5746. With Webb, the science team can now see where stars formed and how they are distributed, in a similar way to how the Hubble Space Telescope is used to study local galaxies. Webb’s view provides a unique opportunity to study star formation and the inner workings of infant galaxies at such an unprecedented distance. Credit: ESA/Webb, NASA & CSA, L. Bradley (STScI), A. Adamo (Stockholm University) and the Cosmic Spring collaboration
With Webb, the science team can now see where stars formed and how they are distributed, in a similar way to how the Hubble Space Telescope is used to study local galaxies. Webb’s view provides a unique opportunity to study star formation and the inner workings of infant galaxies at such an unprecedented distance.
“Webb’s incredible sensitivity and angular resolution at near-infrared wavelengths, combined with gravitational lensing provided by the massive foreground galaxy cluster, enabled this discovery,” explained Larry Bradley of the Space Telescope Science Institute and PI of the Webb observing programme that captured these data.”No other telescope could have made this discovery.”
“The surprise and astonishment was incredible when we opened the Webb images for the first time,” added Adamo. “We saw a little chain of bright dots, mirrored from one side to the other — these cosmic gems are star clusters! Without Webb we would not have known we were looking at star clusters in such a young galaxy!”
In our Milky Way we see ancient globular clusters of stars, which are bound by gravity and have survived for billions of years. These are old relics of intense star formation in the early Universe, but it is not well understood where and when these clusters formed. The detection of massive young star clusters in the Cosmic Gems arc provides us with an excellent view of the early stages of a process that may go on to form globular clusters. The newly detected clusters in the arc are massive, dense and located in a very small region of their galaxy, but they also contribute the majority of the ultraviolet light coming from their host galaxy. The clusters are significantly denser than nearby star clusters. This discovery will help scientists to better understand how infant galaxies formed their stars and where globular clusters formed.
An international team of astronomers have used the NASA/ESA/CSA James Webb Space Telescope to discover gravitationally bound star clusters when the Universe was 460 million years old. This is the first discovery of star clusters in an infant galaxy less than 500 million years after the Big bang. Young galaxies in the early Universe underwent significant burst phases of star formation, generating substantial amounts of ionising radiation. However, because of their cosmological distances, direct studies of their stellar content have proven challenging. Using Webb, an international team of astronomers have now detected five young massive star clusters in the Cosmic Gems arc (SPT0615-JD1), a strongly-lensed galaxy emitting light when the Universe was roughly 460 million years old, looking back across 97% of cosmic time. The Cosmic Gems arc was initially discovered in NASA/ESA Hubble Space Telescope images obtained by the RELICS (Reionization Lensing Cluster Survey) programme of the lensing galaxy cluster SPT-CL J0615−5746. With Webb, the science team can now see where stars formed and how they are distributed, in a similar way to how the Hubble Space Telescope is used to study local galaxies. Webb’s view provides a unique opportunity to study star formation and the inner workings of infant galaxies at such an unprecedented distance. Credit: ESA/Webb, NASA & CSA, L. Bradley (STScI), A. Adamo (Stockholm University) and the Cosmic Spring collaboration
The team notes that this discovery connects a variety of scientific fields.
“These results provide direct evidence that indicates proto-globular clusters formed in faint galaxies during the reionisation era, which contributes to our understanding of how these galaxies have succeeded in reionising the Universe,” explained Adamo. “This discovery also places important constraints on the formation of globular clusters and their initial properties. For instance, the high stellar densities found in the clusters provide us with the first indication of the processes taking place in their interiors, giving new insights into the possible formation of very massive stars and black hole seeds, which are both important for galaxy evolution.”
In the future, the team hopes to build a sample of galaxies for which similar resolutions can be achieved.
“I am confident there are other systems like this waiting to be uncovered in the early Universe, enabling us to further our understanding of early galaxies,”
said Eros Vanzella from the INAF – Astrophysics and Space Science Observatory of Bologna (OAS), Italy, one of the main contributors to the work.
An international team of astronomers have used the NASA/ESA/CSA James Webb Space Telescope to discover gravitationally bound star clusters when the Universe was 460 million years old. This is the first discovery of star clusters in an infant galaxy less than 500 million years after the Big bang. Young galaxies in the early Universe underwent significant burst phases of star formation, generating substantial amounts of ionising radiation. However, because of their cosmological distances, direct studies of their stellar content have proven challenging. Using Webb, an international team of astronomers have now detected five young massive star clusters in the Cosmic Gems arc (SPT0615-JD1), a strongly-lensed galaxy emitting light when the Universe was roughly 460 million years old, looking back across 97% of cosmic time. The Cosmic Gems arc was initially discovered in NASA/ESA Hubble Space Telescope images obtained by the RELICS (Reionization Lensing Cluster Survey) programme of the lensing galaxy cluster SPT-CL J0615−5746. With Webb, the science team can now see where stars formed and how they are distributed, in a similar way to how the Hubble Space Telescope is used to study local galaxies. Webb’s view provides a unique opportunity to study star formation and the inner workings of infant galaxies at such an unprecedented distance. Credit: ESA/Webb, NASA & CSA, L. Bradley (STScI), A. Adamo (Stockholm University) and the Cosmic Spring collaboration
In the meantime, the team is preparing for further observations and spectroscopy with Webb.
“We plan to study this galaxy with Webb’s NIRSpec and MIRI instruments in Cycle 3,” added Bradley. “The NIRSpec observations will allow us to confirm the redshift of the galaxy and to study the ultraviolet emission of the star clusters, which will be used to study their physical properties in more detail. The MIRI observations will allow us to study the properties of ionised gas. The spectroscopic observations will also allow us to spatially map the star formation rate.”
These results have been published today in Nature. The data for this result were captured under Webb observing programme #4212 (PI: L. Bradley).
An international team of astronomers have used the NASA/ESA/CSA James Webb Space Telescope to discover gravitationally bound star clusters when the Universe was 460 million years old. This is the first discovery of star clusters in an infant galaxy less than 500 million years after the Big bang. Young galaxies in the early Universe underwent significant burst phases of star formation, generating substantial amounts of ionising radiation. However, because of their cosmological distances, direct studies of their stellar content have proven challenging. Using Webb, an international team of astronomers have now detected five young massive star clusters in the Cosmic Gems arc (SPT0615-JD1), a strongly-lensed galaxy emitting light when the Universe was roughly 460 million years old, looking back across 97% of cosmic time. The Cosmic Gems arc was initially discovered in NASA/ESA Hubble Space Telescope images obtained by the RELICS (Reionization Lensing Cluster Survey) programme of the lensing galaxy cluster SPT-CL J0615−5746. With Webb, the science team can now see where stars formed and how they are distributed, in a similar way to how the Hubble Space Telescope is used to study local galaxies. Webb’s view provides a unique opportunity to study star formation and the inner workings of infant galaxies at such an unprecedented distance. Credit: ESA/Webb, NASA & CSA, L. Bradley (STScI), A. Adamo (Stockholm University) and the Cosmic Spring collaboration
Bibliographic information:
Angela Adamo, Larry D. Bradley, Eros Vanzella, Adélaïde Claeyssens, Brian Welch4, Jose M Diego, Guillaume Mahler, Masamune Oguri, Keren Sharon, Abdurro’uf, Tiger Yu-Yang Hsiao, Xinfeng Xu, Matteo Messa, Augusto E. Lassen, Erik Zackrisson, Gabriel Brammer, Dan Coe, Vasily Kokorev, Massimo Ricotti, Adi Zitrin, Seiji Fujimoto, Akio K. Inoue, Tom Resseguier, Jane R. Rigby, Yolanda Jiménez-Teja, Rogier A. Windhorst, Takuya Hashimoto and Yoichi Tamura, Bound star clusters observed in a lensed galaxy 460 Myr after the Big Bang, Nature.
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 finds plethora of carbon molecules around ISO-ChaI 147, a young star
An international team of astronomers have used the NASA/ESA/Webb James Webb Space Telescope to study the disc around a young and very low-mass star. The results reveal the richest hydrocarbon chemistry seen to date in a protoplanetary disc (including the first extrasolar detection of ethane) and contribute to our evolving understanding of the diversity of planetary systems.
This is an artist’s impression of a young star surrounded by a protoplanetary disc. An international team of astronomers have used the NASA/ESA/Webb James Webb Space Telescope to study the disc around a young and very low-mass star. The results reveal the richest hydrocarbon chemistry seen to date in a protoplanetary disc (including the first extrasolar detection of ethane) and contribute to our evolving understanding of the diversity of planetary systems. The science team explored the region around a very low-mass star of 0.11 solar masses (known as ISO-ChaI 147). These observations provide insights into the environment as well as basic ingredients for such planets to form. The team found that the gas in the planet-forming region of the star is rich in carbon. This could potentially be because carbon is removed from the solid material from which rocky planets can form, and could explain why Earth is relatively carbon-poor. Credit: NASA/JPL-Caltech
Planets form in discs of gas and dust orbiting young stars. Observations indicate that terrestrial planets are expected to form more efficiently than gas giants in the discs around very low-mass stars. While very low-mass stars have the highest rate of occurrence of orbiting rocky planets, their planetary compositions are largely unknown. For example, the Trappist-1 system (which Webb has studied) consists of seven rocky planets within 0.1 au [1] and their composition is generally assumed to be Earth-like. However, new data from Webb suggests that discs around very low-mass stars may evolve differently from those around more massive stars.
The MIRI Mid-INfrared Disk Survey (MINDS) aims to build a bridge between the chemical inventory of discs and the properties of exoplanets. In a new study, this team explored the region around a very low-mass star of 0.11 solar masses (known as ISO-ChaI 147). These observations provide insights into the environment as well as basic ingredients for such planets to form. The team found that the gas in the planet-forming region of the star is rich in carbon. This could potentially be because carbon is removed from the solid material from which rocky planets can form, and could explain why Earth is relatively carbon-poor.
“Webb has a better sensitivity and spectral resolution than previous infrared space telescopes,” explained lead author Aditya Arabhavi of the University of Groningen in the Netherlands. “These observations are not possible from Earth, because the emissions are blocked by the atmosphere. Previously we could only identify acetylene (C2H2) emission from this object. However, Webb’s higher sensitivity and spectral resolution allowed us to detect weak emission from less abundant molecules. Webb also allowed us to understand that these hydrocarbon molecules are not just diverse but also abundant.”
This graphic presents some of the results from the MIRI Mid-INfrared Disk Survey (MINDS), which aims to build a bridge between the chemical inventory of discs and the properties of exoplanets. In a new study, the science team explored the region around a very low-mass star of 0.11 solar masses (known as ISO-ChaI 147). These observations provide insights into the environment as well as basic ingredients for such planets to form. The team found that the gas in the planet-forming region of the star is rich in carbon. This could potentially be because carbon is removed from the solid material from which rocky planets can form, and could explain why Earth is relatively carbon-poor. The spectrum revealed by Webb’s Mid-InfraRed Instrument (MIRI) shows the richest hydrocarbon chemistry seen to date in a protoplanetary disc, consisting of 13 carbon-bearing molecules up to benzene. This includes the first extrasolar detection of ethane (C2H6), the largest fully-saturated hydrocarbon detected outside our Solar System. Since fully-saturated hydrocarbons are expected to form from more basic molecules, detecting them here gives researchers clues about the chemical environment. The team also successfully detected ethylene (C2H4), propyne (C3H4), and the methyl radical CH3, for the first time in a protoplanetary disc. This graphic highlights the detections of ethane (C2H6), methane (CH4), propyne (C3H4), cyanoacetylene (HC3N), and the methyl radical CH3. Credit: NASA, ESA, CSA, R. Crawford (STScI)
The spectrum revealed by Webb’s Mid-InfraRed Instrument (MIRI) shows the richest hydrocarbon chemistry seen to date in a protoplanetary disc, consisting of 13 carbon-bearing molecules up to benzene. This includes the first extrasolar detection of ethane (C2H6), the largest fully-saturated hydrocarbon [2] detected outside our Solar System. Since fully-saturated hydrocarbons are expected to form from more basic molecules, detecting them here gives researchers clues about the chemical environment. The team also successfully detected ethylene (C2H4), propyne (C3H4), and the methyl radical CH3, for the first time in a protoplanetary disc.
“These molecules have already been detected in our Solar System, for example in comets such as 67P/Churyumov–Gerasimenko and C/2014 Q2 (Lovejoy),” adds Arabhavi. “It is amazing that we can now see the dance of these molecules in the planetary cradles. It is a very different planet-forming environment from what we usually think of.”
The team indicates that these results have large implications for astrochemistry in the inner 0.1 au and the planets forming there. “This is profoundly different from the composition we see in discs around solar-type stars, where oxygen bearing molecules dominate (like carbon dioxide and water),” added team member Inga Kamp, also of the University of Groningen. “This object establishes that these are a unique class of objects.”
“It’s incredible that we can detect and quantify the amount of molecules that we know well on Earth, such as benzene, in an object that is more than 600 light-years away,” added team member Agnés Perrin of Centre National de la Recherche Scientifique in France.
Next, the science team intend to expand their study to a larger sample of such discs around very low-mass stars to develop their understanding of how common such exotic carbon-rich terrestrial planet forming regions are. “The expansion of our study will also allow us to better understand how these molecules can form,” explained team member and PI of the MINDS programme, Thomas Henning, of the Max Planck Institute for Astronomy in Germany. “Several features in the Webb data are also still unidentified, so more spectroscopy is required to fully interpret our observations.”
This work also highlights the crucial need for scientists to collaborate across disciplines. The team notes that these results and the accompanying data can contribute towards other fields including theoretical physics, chemistry and astrochemistry, to interpret the spectra and to investigate new features in this wavelength range.
These results have been published in the journal Science.
Notes
[1] An astronomical unit (AU, or au) is a unit of length effectively equal to the average, or mean, distance between Earth and the Sun, which is defined as roughly 150 million kilometres.
[2] Saturated hydrocarbons are molecules that are made entirely of single carbon-carbon bonds. They cannot incorporate additional atoms into their structure, and are therefore said to be saturated.
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).
Cheers! Webb finds complex organic molecules (COMs), such as ethanol and other icy ingredients for worlds, in early-stage protostars
An international team of astronomers using the NASA/ESA/CSA James Webb Space Telescope have discovered a variety of molecules, ranging from relatively simple ones like methane to complex compounds like acetic acid and ethanol, in early-stage protostars where planets have not yet formed. These are key ingredients for making potentially habitable worlds.
The presence of complex organic molecules (COMs) [1] in the solid phase in protostars was first predicted decades ago from laboratory experiments, and tentative detections of these molecules have been made by other space telescopes. This includes Webb’s Early Release Science Ice Age programme, which discovered diverse ices in the darkest, coldest regions of a molecular cloud measured to date.
This image was taken by Webb’s Mid-InfraRed Instrument (MIRI) of a region parallel to the massive protostar known as IRAS23385. IRAS 2A and IRAS23385 (not visible in this image) were targets for a recent research effort by an international team of astronomers that used Webb to discover that the key ingredients for making potentially habitable worlds are present in early-stage protostars, where planets have not yet formed. With MIRI’s unprecedented spectral resolution and sensitivity, the JOYS+ (James Webb Observations of Young ProtoStars) programme individually identified organic molecules that have been confirmed to be present in interstellar ices. This includes the robust detection of acetaldehyde, ethanol, methyl formate, and likely acetic acid, in the solid phase. Credit: ESA/Webb, NASA, CSA, W. Rocha et al. (Leiden University)
Now, with the unprecedented spectral resolution and sensitivity of Webb’s Mid-InfraRed Instrument (MIRI), as part of the JOYS+ (James Webb Observations of Young ProtoStars) programme, these COMs have been individually identified and confirmed to be present in the interstellar ices. This includes the robust detection of acetaldehyde, ethanol (what we call alcohol), methyl formate, and likely acetic acid (the acid in vinegar), in the solid phase.
“This finding contributes to one of the long-standing questions in astrochemistry,” said team leader Will Rocha of Leiden University in the Netherlands. “What is the origin of COMs in space? Are they made in the gas phase or in ices? The detection of COMs in ices suggests that solid-phase chemical reactions on the surfaces of cold dust grains can build complex kinds of molecules.”
An international team of scientists using the NASA/ESA/CSA James Webb Space Telescope has identified a wealth of complex, carbon-containing (organic) molecules surrounding two protostars. This graphic shows the spectrum of one of the two protostars, IRAS 2A. It includes the fingerprints of acetaldehyde, ethanol, methylformate, and likely acetic acid, in the solid phase. These and other molecules detected there by Webb represent key ingredients for making potentially habitable worlds. Credit: NASA, ESA, CSA, L. Hustak (STScI)
As several COMs, including those detected in the solid phase in this research, were previously detected in the warm gas phase, it is now believed that they originate from the sublimation of ices. Sublimation is to change directly from a solid to a gas without becoming a liquid. Therefore, detecting COMs in ices makes astronomers hopeful about developing an improved understanding of the origins of other even larger molecules in space.
Harold Linnartz[2] led the Laboratory for Astrophysics in Leiden over many years and coordinated the measurements of the data used in this study. Ewine van Dishoeck of Leiden University, one of the coordinators of the JOYS+ programme, shared,
“Harold was particularly happy that in the COM assignments lab work could play an important role as it has been a long time getting here.”
Scientists are also keen to explore to what extent these COMs are transported to planets at much later stages in the evolution of the protostar. COMs in ices are transported more efficiently into planet-forming discs than gas from clouds. These icy COMs can therefore be inherited by comets and asteroids which in turn may collide with planets in formation. In that scenario COMs can be delivered to those planets, potentially providing the ingredients for life to flourish.
The science team also detected simpler molecules, including methane, formic acid (which makes the sting of ants painful), sulphur dioxide, and formaldehyde. Sulphur dioxide in particular allows the team to investigate the sulphur budget available in protostars. In addition, it is of prebiotic interest because existing research suggests that sulphur-containing compounds played an important role in driving metabolic reactions on the primitive Earth. Negative ions were also detected [3]; they form part of salts that are crucial for developing further chemical complexity at higher temperatures. This indicates that the ices may be much more complex and require further research.
Of particular interest is that one of the sources investigated, IRAS 2A, is characterised as a low-mass protostar. IRAS 2A may therefore have similarities with the primordial stages of our own Solar System. If that is the case, the chemical species identified in this protostar may have been present in the first stages of development of our Solar System and were later delivered to the primitive Earth.
All of these molecules can become part of comets and asteroids and eventually new planetary systems when the icy material is transported inward to the planet-forming discs as the protostellar system evolves,” said van Dishoeck. “We look forward to following this astrochemical trail step by step with more Webb data in the coming years.”
Other recent work by Pooneh Nazari of Leiden Observatory also raises astronomers’ hopes for finding more complexity in ices, following the tentative detections of methyl cyanide and ethyl cyanide from Webb NIRSpec data. Nazari says,
“It is impressive how Webb now allows us to further probe the ice chemistry down to the level of cyanides, important ingredients in prebiotic chemistry.”
Notes
[1] A molecule is a particle made up of two or more atoms that are held together by chemical bonds. A complex organic molecule is a molecule with multiple carbon atoms.
[2] These results are dedicated to team member Professor Harold Linnartz, who unexpectedly passed away in December 2023, shortly after the acceptance of this paper. Linnartz made significant contributions to the study of gaseous and icy molecules in space. He was the Director of the Leiden Laboratory for Astrophysics and many of the ice-phase spectra of simple and complex molecules used in this research were collected by students under his supervision. Linnartz was thrilled with the quality of the Webb data and the significance of these results for astrochemistry.
[3] An ion is an atom or molecule that has an overall electrical charge, resulting from an excess or deficit in the number of negative electrons compared to the number of positive protons in the ion. A negative ion is an ion with a net negative charge (so a surplus of electrons).
Two new images from the NASA/ESA/CSA James Webb Space Telescope’s NIRCam (Near-Infrared Camera) and MIRI (Mid-Infrared Instrument) showcase the star-forming region NGC 604, located in the Triangulum Galaxy (M33), 2.73 million light-years away from Earth. In these images, cavernous bubbles and stretched-out filaments of gas etch a more detailed and complete tapestry of star birth than seen in the past.
Sheltered among NGC 604’s dusty envelopes of gas are more than 200 of the hottest, most massive kinds of stars, all in the early stages of their lives. These types of stars are known as B-types and O-types, the latter of which can be more than 100 times the mass of our own Sun. It’s quite rare to find this concentration of them in the nearby Universe. In fact, there’s no similar region within our own Milky Way galaxy.
This concentration of massive stars, combined with its relatively close distance, means NGC 604 gives astronomers an opportunity to study these objects at a fascinating time early in their life.
This image from the NASA/ESA/CSA James Webb Space Telescope’s NIRCam (Near-Infrared Camera) of star-forming region NGC 604 shows how stellar winds from bright, hot young stars carve out cavities in surrounding gas and dust. The bright orange streaks in this image signify the presence of carbon-based molecules known as polycyclic aromatic hydrocarbons, or PAHs. As you travel further from the immediate cavities of dust where the star is forming, the deeper red signifies molecular hydrogen. This cooler gas is a prime environment for star formation. Ionised hydrogen from ultraviolet radiation appears as a white and blue ghostly glow. NGC 604 is located in the Triangulum Galaxy (M33), 2.73 million light-years away from Earth. It provides an opportunity for astronomers to study a high concentration of very young, massive stars in a nearby region. Credit: NASA, ESA, CSA, STScI
In Webb’s near-infrared NIRCam image, the most noticeable features are tendrils and clumps of emission that appear bright red, extending out from areas that look like clearings, or large bubbles in the nebula. Stellar winds from the brightest and hottest young stars have carved out these cavities, while ultraviolet radiation ionises the surrounding gas. This ionised hydrogen appears as a white and blue ghostly glow.
The bright orange streaks in the Webb near-infrared image signify the presence of carbon-based molecules known as polycyclic aromatic hydrocarbons, or PAHs. This material plays an important role in the interstellar medium and the formation of stars and planets, but its origin is a mystery. As you travel further from the immediate clearings of dust, the deeper red signifies molecular hydrogen. This cooler gas is a prime environment for star formation.
Webb’s exquisite resolution also provides insights into features that previously appeared unrelated to the main cloud. For example, in Webb’s image, there are two bright, young stars carving out holes in dust above the central nebula, connected through diffuse red gas. In visible-light imaging from the NASA/ESA Hubble Space Telescope, these appeared as separate splotches.
This image from the NASA/ESA/CSA James Webb Space Telescope’s MIRI (Mid-Infrared Instrument) of star-forming region NGC 604 shows how large clouds of cooler gas and dust glow at mid-infrared wavelengths. This region is a hotbed of star formation and home to more than 200 of the hottest, most massive kinds of stars, all in the early stages of their lives. In the MIRI view of NGC 604, there are noticeably fewer stars than Webb’s NIRCam image. This is because hot stars emit much less light at these wavelengths. Some of the stars seen in this image are red supergiants — stars that are cool but very large, hundreds of times the diameter of our Sun. The blue tendrils of material signify the presence of polycyclic aromatic hydrocarbons, or PAHs. Credit: NASA, ESA, CSA, STScI
Webb’s view in mid-infrared wavelengths also illustrates a new perspective on the diverse and dynamic activity of this region. In the MIRI view of NGC 604, there are noticeably fewer stars. This is because hot stars emit much less light at these wavelengths, while the larger clouds of cooler gas and dust glow. Some of the stars seen in this image from the surrounding galaxy are red supergiants — stars that are cool but very large, hundreds of times the diameter of our Sun. Additionally, some of the background galaxies that appeared in the NIRCam image also fade. In the MIRI image, the blue tendrils of material signify the presence of PAHs.
NGC 604 is estimated to be around 3.5 million years old. The cloud of glowing gases extends to some 1300 light-years across.
This image from the NASA/ESA/CSA James Webb Space Telescope’s NIRCam (Near-Infrared Camera) of star-forming region NGC 604 shows how stellar winds from bright, hot young stars carve out cavities in surrounding gas and dust. The bright orange streaks in this image signify the presence of carbon-based molecules known as polycyclic aromatic hydrocarbons, or PAHs. As you travel further from the immediate cavities of dust where the star is forming, the deeper red signifies molecular hydrogen. This cooler gas is a prime environment for star formation. Ionised hydrogen from ultraviolet radiation appears as a white and blue ghostly glow. NGC 604 is located in the Triangulum Galaxy (M33), 2.73 million light-years away from Earth. It provides an opportunity for astronomers to study a high concentration of very young, massive stars in a nearby region. Credit: NASA, ESA, CSA, STScI
