Webb’s Titan forecast: partly cloudy with occasional methane showers
Astronomers see evidence of clouds bubbling up over Titan’s northern hemisphere.
A science team has combined data from the NASA/ESA/CSA James Webb Space Telescope and the Keck II telescope to see evidence of cloud convection on Saturn’s moon Titan in the northern hemisphere for the first time. Most of Titan’s lakes and seas are located in that hemisphere, and are likely replenished by an occasional rain of methane and ethane. Webb also has detected a key carbon-containing molecule that gives insight into the chemical processes in Titan’s complex atmosphere.
These infrared-light images of Titan were taken by the NASA/ESA/CSA James Webb Space Telescope on 11 July 2023. They show methane clouds appearing at different altitudes in Titan’s northern hemisphere. On the left side is a representative-colour image (1.4 microns is coloured blue, 1.5 microns is green, and 2.0 microns is red: filters F140M, F150W, and F200W, respectively). In the middle is a single-wavelength image taken by Webb at 2.12 microns. This wavelength is predominantly emitted from Titan’s lower troposphere. The rightmost image shows emission at 1.64 microns, which favours higher altitudes, in Titan’s upper troposphere and stratosphere (an atmospheric layer above the troposphere). Credit: NASA, ESA, CSA, STScI, Keck Observatory
Saturn’s moon Titan is an intriguing world cloaked in a yellowish, smoggy haze. Similar to Earth, the atmosphere is mostly nitrogen and has weather, including clouds and rain. Unlike Earth, whose weather is driven by evaporating and condensing water, frigid Titan has a methane (CH4) cycle. It evaporates from the surface and rises into the atmosphere, where it condenses to form methane clouds. Occasionally it falls as a chilly, oily rain onto a solid surface where water ice is hard as rocks.
“Titan is the only other place in our Solar System that has weather like Earth, in the sense that it has clouds and rainfall onto a surface,” explained lead author Conor Nixon of NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
The team observed Titan in November 2022 and July 2023 using both Webb and one of the twin ground-based W.M. Keck telescopes. Those observations not only showed clouds in the mid and high northern latitudes on Titan — the hemisphere where it is currently summer — but also showed those clouds apparently rising to higher altitudes over time. While previous studies have observed cloud convection at southern latitudes, this is the first time evidence for such convection has been seen in the north. This is significant because most of Titan’s lakes and seas are located in its northern hemisphere and evaporation from lakes is a major potential methane source.
On Earth the lowest layer of the atmosphere, or troposphere, extends up to an altitude of about 12 kilometers. However, on Titan, whose lower gravity allows the atmospheric layers to expand, the troposphere extends up to about 45 kilometers. Webb and Keck used different infrared filters to probe to different depths in Titan’s atmosphere, allowing astronomers to estimate the altitudes of the clouds. The science team observed clouds that appeared to move to higher altitudes over a period of days, although they were not able to directly see any precipitation occurring.
“Webb’s observations were taken at the end of Titan’s northern summer, which is a season that we were unable to observe with the Cassini-Huygens mission,” said Thomas Cornet of the European Space Agency, a co-author of the study. “Together with ground-based observations, Webb is giving us precious new insights into Titan’s atmosphere, that we hope to be able to investigate much closer-up in the future with a possible ESA mission to visit the Saturn system.”
Titan’s chemistry
Titan is an object of high astrobiological interest due to its complex organic (carbon-containing) chemistry, despite its frigid temperature of about -180 degrees Celsius. Organic molecules form the basis of all life on Earth, and studying them on a world like Titan may help scientists understand the processes that led to the origin of life on Earth.
The basic ingredient that drives much of Titan’s chemistry is methane. Methane in Titan’s atmosphere gets split apart by sunlight or energetic electrons from Saturn’s magnetosphere, and then recombines with other molecules to make substances like ethane (C2H6) along with more complex carbon-bearing molecules.
Webb’s data provided a key missing piece for our understanding of the chemical processes: a definitive detection of the methyl radical CH3. This molecule (called “radical” because it has a “free” electron that is not in a chemical bond) forms when methane is broken apart. Detecting this substance means that scientists can see chemistry in action on Titan for the first time, rather than just the starting ingredients and the end products.
“For the first time we can see the chemical cake while it’s rising in the oven, instead of just the starting ingredients of flour and sugar, and then the final, iced cake,” said co-author Stefanie Milam of the Goddard Space Flight Center.
The future of Titan’s atmosphere
This hydrocarbon chemistry has long-term implications for the future of Titan. When methane is broken apart in the upper atmosphere, some of it recombines to make other molecules that eventually end up on Titan’s surface in one chemical form or another, while some hydrogen escapes from the atmosphere. As a result, methane will be depleted over time, unless there is some source to replenish it.
A similar process occurred on Mars, where water molecules were broken up and the resulting hydrogen lost to space. The result was the dry, desert planet we see today.
“On Titan, methane is a consumable. It’s possible that it is being constantly resupplied and fizzing out of the crust and interior over billions of years. If not, eventually it will all be gone and Titan will become a mostly airless world of dust and dunes,” said Nixon.
This data was taken as part of Heidi Hammel’s Guaranteed Time Observations program to study the Solar System. The results were published in the journal Nature Astronomy.
These images of Titan were taken by the NASA/ESA/CSA James Webb Space Telescope on 11July 2023 (top row) and the ground-based W.M. Keck Observatories on 14 July 2023 (bottom row). They show methane clouds (denoted by the white arrows) appearing at different altitudes in Titan’s northern hemisphere. On the left side are representative-colour images from both telescopes. In the Webb image light at 1.4 microns is coloured blue, 1.5 microns is green, and 2.0 microns is red (filters F140M, F150W, and F200W, respectively). In the Keck image light at 2.13 microns is coloured blue, 2.12 microns is green, and 2.06 microns is red (H2 1-0, Kp, and He1b, respectively). In the middle column are single-wavelength images taken by Webb and Keck at 2.12 microns. This wavelength is sensitive to emission from Titan’s lower troposphere. The rightmost images show emission at 1.64 microns (Webb) and 2.17 microns (Keck), which favour higher altitudes, in Titan’s upper troposphere and stratosphere (an atmospheric layer above the troposphere). It demonstrates that the clouds are seen at higher altitudes on July 14 than earlier on July 11, indicative of upward motion. Credit: NASA, ESA, CSA, STScI, Keck Observatory
Bibliographic information:
Nixon, C.A., Bézard, B., Cornet, T. et al., The atmosphere of Titan in late northern summer from JWST and Keck observations, Nat Astron (2025), DOI: https://doi.org/10.1038/s41550-025-02537-3
The NASA/ESA/CSA James Webb Space Telescope has captured new details of the auroras on our Solar System’s largest planet. The dancing lights observed on Jupiter are hundreds of times brighter than those seen on Earth. With Webb’s advanced sensitivity, astronomers have studied the phenomena to better understand Jupiter’s magnetosphere.
The NASA/ESA/CSA James Webb Space Telescope has captured new details of the auroras on our Solar System’s largest planet. The dancing lights observed on Jupiter are hundreds of times brighter than those seen on Earth. These observations of Jupiter’s auroras were captured with Webb’s Near-InfraRed Camera (NIRCam) on 25 December 2023 (F335M filter). Scientists found that the emission from the trihydrogen ion, known as H3+, is far more variable than previously believed. H3+ is created by the impact of high energy electrons on molecular hydrogen. Because this emission shines brightly in the infrared, Webb’s instruments are well equipped to observe it. Credit: ESA/Webb, NASA, CSA, J. Nichols (University of Leicester), M. Zamani (ESA/Webb)
The auroras are created when high-energy particles enter a planet’s atmosphere near its magnetic poles and collide with atoms of gas. Not only are the auroras on Jupiter huge in size, they are also hundreds of times more energetic than auroras on Earth. Here, auroras are caused by solar storms — when charged particles rain down on the upper atmosphere, excite gases and cause them to glow colours of red, green and purple. Meanwhile, Jupiter has an additional source for its auroras; the strong magnetic field of the gas giant grabs charged particles from its surroundings. This includes not only the charged particles within the solar wind but also the particles thrown into space by its orbiting moon Io, known for its numerous and large volcanoes. Io’s volcanoes spew particles that, remarkably, escape the moon’s gravity and orbit Jupiter. A barrage of charged particles unleashed by the sun during solar storms also reaches the planet. Jupiter’s large and powerful magnetic field captures charged particles and accelerates them to tremendous speeds. These speedy particles slam into the planet’s atmosphere at high energies, which excites the gas and causes it to glow.
Now, Webb’s unique capabilities are providing new insights into the auroras on Jupiter. The telescope’s sensitivity allows astronomers to increase the shutter speed in order to capture fast-varying auroral features. New data was captured with Webb’s Near-InfraRed Camera (NIRCam) on Christmas Day 2023 by a team of scientists led by Jonathan Nichols from the University of Leicester in the United Kingdom.
“What a Christmas present it was – it just blew me away!” shared Nichols. “We wanted to see how quickly the auroras change, expecting it to fade in and out ponderously, perhaps over a quarter of an hour or so. Instead we observed the whole auroral region fizzing and popping with light, sometimes varying by the second.”
The NASA/ESA/CSA James Webb Space Telescope has captured new details of the auroras on our Solar System’s largest planet. The dancing lights observed on Jupiter are hundreds of times brighter than those seen on Earth. These observations of Jupiter’s auroras (shown on the left of the above image) were captured with Webb’s Near-InfraRed Camera (NIRCam) on 25 December 2023 (F335M filter). Scientists found that the emission from the trihydrogen ion, known as H3+, is far more variable than previously believed. H3+ is created by the impact of high energy electrons on molecular hydrogen. Because this emission shines brightly in the infrared, Webb’s instruments are well equipped to observe it. The image on the right shows the planet Jupiter to indicate the location of the observed auroras, which was originally published in 2023 (F164N, F212N, and F360M filters). Credit: NASA, ESA, CSA, STScI, Ricardo Hueso (UPV), Imke de Pater (UC Berkeley), Thierry Fouchet (Observatory of Paris), Leigh Fletcher (University of Leicester), Michael H. Wong (UC Berkeley), Joseph DePasquale (STScI), J. Nichols (University of Leicester), M. Zamani (ESA/Webb)
The team’s data found that the emission from the trihydrogen ion, known as H3+, is far more variable than previously believed. The observations will help develop scientists’ understanding of how Jupiter’s upper atmosphere is heated and cooled.
The team also uncovered some unexplained observations in their data.
“What made these observations even more special is that we also took pictures simultaneously in the ultraviolet with the NASA/ESA Hubble Space Telescope,” added Nichols. “Bizarrely, the brightest light observed by Webb had no real counterpart in Hubble’s pictures. This has left us scratching our heads. In order to cause the combination of brightness seen by both Webb and Hubble, we need to have an apparently impossible combination of high quantities of very low energy particles hitting the atmosphere – like a tempest of drizzle! We still don’t understand how this happens.”
The team now plans to study this discrepancy between the Hubble and Webb data and to explore the wider implications for Jupiter’s atmosphere and space environment. They also intend to follow up this research with more Webb observations, which they can compare with data from NASA’s Juno spacecraft to better explore the cause of the enigmatic bright emission. These insights may also support the European Space Agency’s Jupiter Icy Moons Explorer, Juice, which is en route to Jupiter to make detailed observations of the giant gas planet and its three large ocean-bearing moons – Ganymede, Callisto and Europa. Juice will take a look at Jupiter’s auroras with seven unique scientific instruments, including two imagers. These close-up measurements will help us understand how the planet’s magnetic field and atmosphere interact, as well as the effect that charged particles from Io and the other moons have on Jupiter’s atmosphere.
The NASA/ESA/CSA James Webb Space Telescope has captured new details of the auroras on our Solar System’s largest planet. The dancing lights observed on Jupiter are hundreds of times brighter than those seen on Earth. These observations of Jupiter’s auroras were captured with Webb’s Near-InfraRed Camera (NIRCam) on 25 December 2023 (F335M filter). Scientists found that the emission from the trihydrogen ion, known as H3+, is far more variable than previously believed. H3+ is created by the impact of high energy electrons on molecular hydrogen. Because this emission shines brightly in the infrared, Webb’s instruments are well equipped to observe it. The timestamps indicated in the lower right corner of each image indicates the time (UTC) when these observations were taken on 25 December 2023. Credit: ESA/Webb, NASA, CSA, J. Nichols(University of Leicester), M. Zamani (ESA/Webb)
These results were obtained from data using Webb’s Cycle 2 observing programme #4566 and Hubble’s observing programme #17471. The results were published today in Nature Communications.
Hubble provides a new view of a galactic favourite, Sombrero Galaxy, or Messier 104
In anticipation of the upcoming 35th anniversary of the NASA/ESA Hubble Space Telescope, ESA/Hubble is continuing the celebrations with a new image of the Sombrero Galaxy, also known as Messier 104. An eye-catching target for Hubble and a favourite of amateur astronomers, the enigmatic Sombrero Galaxy has features of both spiral and elliptical galaxies. This image incorporates new processing techniques that highlight the unique structure of this galaxy.
As part of ESA/Hubble’s 35th anniversary celebrations, a new image series is being shared to revisit stunning Hubble targets that were previously released. First, a new image of NGC 346 was published. Now, ESA/Hubble is revisiting a fan-favourite galaxy with new image processing techniques. The new image reveals finer detail in the galaxy’s disc, as well as more background stars and galaxies.
Several Hubble images of the Sombrero Galaxy have been released over the past two decades, including this well-known Hubble image from October 2003. In November 2024, the NASA/ESA/CSA James Webb Space Telescope also gave an entirely new perspective on this striking galaxy.
Located around 30 million light-years away in the constellation Virgo, the Sombrero Galaxy is instantly recognisable. Viewed nearly edge on, the galaxy’s softly luminous bulge and sharply outlined disc resemble the rounded crown and broad brim of the Mexican hat from which the galaxy gets its name.
Though the Sombrero Galaxy is packed with stars, it’s surprisingly not a hotbed of star formation. Less than one solar mass of gas is converted into stars within the knotted, dusty disc of the galaxy each year. Even the galaxy’s central supermassive black hole, which at 9 billion solar masses is more than 2000 times more massive than the Milky Way’s central black hole, is fairly calm.
The galaxy is too faint to be spotted with unaided vision, but it is readily viewable with a modest amateur telescope. Seen from Earth, the galaxy spans a distance equivalent to roughly one third of the diameter of the full Moon. The galaxy’s size on the sky is too large to fit within Hubble’s narrow field of view, so this image is actually a mosaic of several images stitched together.
One of the things that makes this galaxy especially notable is its viewing angle, which is inclined just six degrees off of the galaxy’s equator. From this vantage point, intricate clumps and strands of dust stand out against the brilliant white galactic nucleus and bulge, creating an effect not unlike Saturn and its rings — but on an epic galactic scale.
At the same time, this extreme angle makes it difficult to discern the structure of the Sombrero Galaxy. It’s not clear whether it’s a spiral galaxy, like our own Milky Way, or an elliptical galaxy. Curiously, the galaxy’s disc seems like a fairly typical disc for a spiral galaxy, and its spheroidal bulge and halo seem fairly typical for an elliptical galaxy — but the combination of the two components resembles neither a spiral nor an elliptical galaxy.
Researchers have used Hubble to investigate the Sombrero Galaxy, measuring the amount of metals (what astronomers call elements heavier than helium) in stars in the galaxy’s expansive halo. This type of measurement can illuminate a galaxy’s history, potentially revealing whether it has merged with other galaxies in the past. In the case of the Sombrero Galaxy, extremely metal-rich stars in the halo point to a possible merger with a massive galaxy several billion years ago. An ancient galactic clash, hinted at by Hubble’s sensitive measurements, could explain the Sombrero Galaxy’s distinctive appearance.
This image was developed using data from the Hubble observing programme #9714 (PI: K. Noll)
Located around 30 million light-years away in the constellation Virgo, the Sombrero Galaxy is instantly recognisable. Viewed nearly edge on, the galaxy’s softly luminous bulge and sharply outlined disc resemble the rounded crown and broad brim of the Mexican hat from which the galaxy gets its name. Though the Sombrero Galaxy is packed with stars, it’s surprisingly not a hotbed of star formation. Less than one solar mass of gas is converted into stars within the knotted, dusty disc of the galaxy each year. Even the galaxy’s central supermassive black hole, which at 9 billion solar masses is more than 2000 times more massive than the Milky Way’s central black hole, is fairly calm. The galaxy is too faint to be spotted with unaided vision, but it is readily viewable with a modest amateur telescope. Seen from Earth, the galaxy spans a distance equivalent to roughly one third of the diameter of the full Moon. The galaxy’s size on the sky is too large to fit within Hubble’s narrow field of view, so this image is actually a mosaic of several images stitched together. Credit: ESA/Hubble & NASA, K. Noll
NGC 1514: dying star’s energetic display comes into full focus
The NASA/ESA/CSA James Webb Space Telescope has taken the most detailed image of planetary nebula NGC 1514 to date thanks to its unique mid-infrared observations. Webb’s image brings out the nebula’s nuances, particularly its “fuzzy” dusty rings. Also look for holes in the central pink region where material has broken through. Two central stars, which appear as one in Webb’s image, formed this scene over thousands of years — and will keep at it for thousands more.
The NASA/ESA/CSA James Webb Space Telescope has taken the most detailed image of planetary nebula NGC 1514 to date thanks to its unique mid-infrared observations. Webb shows its rings as “fuzzy,” intricate clumps of dust. It’s also easier to see holes punched through the bright pink central region. Credit: NASA, ESA, CSA, STScI, Michael Ressler (NASA-JPL), Dave Jones (IAC)
Gas and dust ejected by a dying star at the heart of NGC 1514 came into complete focus thanks to mid-infrared data from the James Webb Space Telescope. Its rings, which are only detected in infrared light, now look like fuzzy clumps arranged in tangled patterns, and a network of clearer holes close to the central stars shows where faster material punched through.
The rings around NGC 1514 were discovered in 2010, but now Webb is allowing scientists to comprehensively examine the turbulent nature of this nebula.
This scene has been forming for at least 4,000 years — and will continue to change over many more millennia. At the center are two stars that appear as one in Webb’s observation, and are set off with brilliant diffraction spikes. The stars follow a tight, elongated nine-year orbit and are draped in an arc of dust represented in orange.
One of these stars, which used to be several times more massive than our Sun, took the lead role in producing this scene. Once the star’s outer layers were exhausted, only its hot, compact core remained. As a white dwarf star, its winds both sped up and weakened, which might have swept up material into thin shells.
Its hourglass shape
Webb’s observations show the nebula is at a 60-degree angle, which makes it look like a can is being poured, but it’s far more likely that NGC 1514 takes the shape of an hourglass with the ends lopped off. Look for hints of its pinched waist near top left and bottom right, where the dust is orange and drifts into shallow V-shapes. When this star was at its peak of losing material, the companion could have gotten very close, resulting in these unusual shapes. Instead of producing a sphere, this interaction might have instead formed rings.
Though the outline of NGC 1514 is clearest, the hourglass also has “sides” that are part of its three-dimensional shape. Look for the dim, semi-transparent orange clouds between its rings that give the nebula body.
Two infrared views of NGC 1514. At left is an observation from NASA’s Wide-field Infrared Survey Explorer (WISE). At right is a more refined image from NASA’s James Webb Space Telescope. Credit: NASA, ESA, CSA, STScI, NASA-JPL, Caltech, UCLA, Michael Ressler (NASA-JPL), Dave Jones (IAC)
A network of dappled structures
The nebula’s two rings are unevenly illuminated in Webb’s observations, appearing more diffuse at bottom left and top right. They also look fuzzy, or textured. Scientists believe the rings are primarily made up of very small dust grains, which, when hit by ultraviolet light from the white dwarf star, heat up enough to be detected by Webb.
In addition to dust, the telescope also revealed oxygen in its clumpy pink center, particularly at the edges of the bubbles or holes.
NGC 1514 is also notable for what is absent. Carbon and more complex versions of it, smoke-like material known as polycyclic aromatic hydrocarbons, are common in planetary nebulae (expanding shells of glowing gas expelled by stars late in their lives). Neither were detected in NGC 1514. More complex molecules might not have had time to form due to the orbit of the two central stars, which mixed up the ejected material. A simpler composition also means that the light from both stars reaches much farther, which is why we see the faint, cloud-like rings.
What about the bright blue star to the lower left with slightly smaller diffraction spikes than the central stars? It’s not part of this scene. In fact, this star lies closer to us.
This planetary nebula has been studied by astronomers since the late 1700s. Astronomer William Herschel noted in 1790 that NGC 1514 was the first deep sky object to appear genuinely cloudy — he could not resolve what he saw into individual stars within a cluster, like other objects he catalogued. With Webb, our view is considerably clearer.
NGC 1514 lies in the Taurus constellation approximately 1,500 light-years from Earth.
This image of planetary nebula NGC 1514, 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 labeled in light-years, which is the distance that light travels in one Earth-year. (It takes 0.6 years for light to travel a distance equal to the length of the scale bar.) One light-year is equal to about 5.88 trillion miles or 9.46 trillion kilometers. This image shows invisible mid-infrared wavelengths of light that have been translated into visible-light colours. The colour key shows which MIRI filters were used when collecting the light. The colour of each filter name is the visible light colour used to represent the infrared light that passes through that filter. Credit: NASA, ESA, CSA, STScI, Michael Ressler (NASA-JPL), Dave Jones (IAC)
Webb discovers the incredibly distant galaxy JADES-GS-z13-1 in mysteriously clearing fog of early Universe
Using the unique infrared sensitivity of the NASA/ESA/CSA James Webb Space Telescope, researchers can examine ancient galaxies to probe secrets of the early universe. Now, an international team of astronomers has identified bright hydrogen emission from a galaxy in an unexpectedly early time in the Universe’s history. The surprise finding is challenging researchers to explain how this light could have pierced the thick fog of neutral hydrogen that filled space at that time.
The incredibly distant galaxy GS-z13-1, observed just 330 million years after the Big Bang, was initially discovered with deep imaging from the NASA/ESA/CSA James Webb Space Telescope. Now, an international team of astronomers has definitively identified powerful hydrogen emission from this galaxy at an unexpectedly early period in the Universe’s history, a probable sign that we are seeing some of the first hot stars from the dawn of the Universe. This image shows the galaxy GS-z13-1 (the red dot at centre), imaged with Webb’s Near-Infrared Camera (NIRCam) as part of the JWST Advanced Deep Extragalactic Survey (JADES) programme. These data from NIRCam allowed researchers to identify GS-z13-1 as an incredibly distant galaxy, and to put an estimate on its redshift value. Webb’s unique infrared sensitivity is necessary to observe galaxies at this extreme distance, whose light has been redshifted into infrared wavelengths during its long journey across the cosmos. To confirm the galaxy’s redshift, the team turned to Webb’s Near-Infrared Spectrograph (NIRSpec) instrument. With new observations permitting advanced spectroscopy of the galaxy’s emitted light, the team not only confirmed GS-z13-1’s redshift of 13.0, they also revealed the strong presence of a type of ultraviolet radiation called Lyman-α emission. This is a telltale sign of the presence of newly forming stars, or a possible active galactic nucleus in the galaxy, but at a much earlier time than astronomers had thought possible. The result holds great implications for our understanding of the Universe. Credit: ESA/Webb, NASA, STScI, CSA, JADES Collaboration, Brant Robertson (UC Santa Cruz), Ben Johnson (CfA), Sandro Tacchella (Cambridge), Phill Cargile (CfA), J. Witstok, P. Jakobsen, A. Pagan (STScI), M. Zamani (ESA/Webb)
A key science goal of the NASA/ESA/CSA James Webb Space Telescope has been to see further than ever before into the distant past of our Universe, when the first galaxies were forming after the Big Bang. This search has already yielded record-breaking galaxies, in observing programmes such as the JWST Advanced Deep Extragalactic Survey (JADES). Webb’s extraordinary sensitivity to infrared light also opens entirely new avenues of research into when and how such galaxies formed, and their effects on the Universe at the time known as cosmic dawn. Researchers studying one of those very early galaxies have now made a discovery in the spectrum of its light, that challenges our established understanding of the Universe’s early history.
Webb discovered the incredibly distant galaxy JADES-GS-z13-1, observed to be at just 330 million years after the Big Bang, in images taken by Webb’s NIRCam (Near-Infrared Camera) as part of the JADES programme. Researchers used the galaxy’s brightness in different infrared filters to estimate its redshift, which measures a galaxy’s distance from Earth based on how its light has been stretched out during its journey through expanding space.
The incredibly distant galaxy GS-z13-1, observed just 330 million years after the Big Bang, was initially discovered with deep imaging from the NASA/ESA/CSA James Webb Space Telescope. Now, an international team of astronomers has definitively identified powerful hydrogen emission from this galaxy at an unexpectedly early period in the Universe’s history, a probable sign that we are seeing some of the first hot stars from the dawn of the Universe. Data from NIRCam allowed researchers to identify GS-z13-1 as an incredibly distant galaxy, and to put an estimate on its redshift value. Webb’s unique infrared sensitivity is necessary to observe galaxies at this extreme distance, whose light has been redshifted into infrared wavelengths during its long journey across the cosmos. To confirm the galaxy’s redshift, the team turned to Webb’s Near-Infrared Spectrograph (NIRSpec) instrument. This graphic shows the light from galaxy GS-z13-1, dispersed by NIRSpec into its component near-infrared wavelengths. This graphic indicates very bright Lyman-α emission from the galaxy, which has been redshifted to an infrared wavelength. Not only does this emission in GS-z13-1’s spectrum confirm the galaxy’s extreme redshift, it is a telltale sign of the presence of newly forming stars, or a possible active galactic nucleus in the galaxy. Appearing at a much earlier time than astronomers had thought possible, the discovery of this Lyman-α emission holds great implications for our understanding of the Universe. Credit: ESA/Webb, NASA, CSA, STScI, J. Olmsted (STScI), S. Carniani (Scuola Normale Superiore), P. Jakobsen
The NIRCam imaging yielded an initial redshift estimate of 12.9. Seeking to confirm its extreme redshift, an international team led by Joris Witstok of the University of Cambridge in the United Kingdom as well as the Cosmic Dawn Center and the University of Copenhagen in Denmark, then observed the galaxy using Webb’s Near-Infrared Spectrograph (NIRSpec) instrument.
The incredibly distant galaxy GS-z13-1, observed just 330 million years after the Big Bang, was initially discovered with deep imaging from the NASA/ESA/CSA James Webb Space Telescope. Now, an international team of astronomers has definitively identified powerful hydrogen emission from this galaxy at an unexpectedly early period in the Universe’s history, a probable sign that we are seeing some of the first hot stars from the dawn of the Universe. This image shows the location of the galaxy GS-z13-1 in the GOODS-S field, as well as the galaxy itself, imaged with Webb’s Near-Infrared Camera (NIRCam) as part of the JWST Advanced Deep Extragalactic Survey (JADES) programme. These data from NIRCam allowed researchers to identify GS-z13-1 as an incredibly distant galaxy, and to put an estimate on its redshift value. Webb’s unique infrared sensitivity is necessary to observe galaxies at this extreme distance, whose light has been redshifted into infrared wavelengths during its long journey across the cosmos. To confirm the galaxy’s redshift, the team turned to Webb’s Near-Infrared Spectrograph (NIRSpec) instrument. With new observations permitting advanced spectroscopy of the galaxy’s emitted light, the team not only confirmed GS-z13-1’s redshift of 13.0, they also revealed the strong presence of a type of ultraviolet radiation called Lyman-α emission. This is a telltale sign of the presence of newly forming stars, or a possible active galactic nucleus in the galaxy, but at a much earlier time than astronomers had thought possible. The result holds great implications for our understanding of the Universe. Credit: ESA/Webb, NASA, STScI, CSA, JADES Collaboration, Brant Robertson (UC Santa Cruz), Ben Johnson (CfA), Sandro Tacchella (Cambridge), Phill Cargile (CfA), J. Witstok, P. Jakobsen, A. Pagan (STScI), M. Zamani (ESA/Webb)
In the resulting spectrum, the redshift was confirmed to be 13.0. This equates to a galaxy seen just 330 million years after the Big Bang, a small fraction of the Universe’s present age of 13.8 billion years old. But an unexpected feature stood out as well: one specific, distinctly bright wavelength of light, identified as the Lyman-α emission radiated by hydrogen atoms.[1] This emission was far stronger than astronomers thought possible at this early stage in the Universe’s development.
“The early Universe was bathed in a thick fog of neutral hydrogen,” explained Roberto Maiolino, a team member from the University of Cambridge and University College London. “Most of this haze was lifted in a process called reionisation, which was completed about one billion years after the Big Bang. GS-z13-1 is seen when the Universe was only 330 million years old, yet it shows a surprisingly clear, telltale signature of Lyman-α emission that can only be seen once the surrounding fog has fully lifted. This result was totally unexpected by theories of early galaxy formation and has caught astronomers by surprise.”
Before and during the epoch of reionisation [2], the immense amounts of neutral hydrogen fog surrounding galaxies blocked any energetic ultraviolet light they emitted, much like the filtering effect of coloured glass. Until enough stars had formed and were able to ionise the hydrogen gas, no such light — including Lyman-α emission — could escape from these fledgling galaxies to reach Earth. The confirmation of Lyman-α radiation from this galaxy, therefore, has great implications for our understanding of the early Universe. Team member Kevin Hainline of the University of Arizona in the United States, says
“We really shouldn’t have found a galaxy like this, given our understanding of the way the Universe has evolved. We could think of the early Universe as shrouded with a thick fog that would make it exceedingly difficult to find even powerful lighthouses peeking through, yet here we see the beam of light from this galaxy piercing the veil. This fascinating emission line has huge ramifications for how and when the Universe reionised.”
The source of the Lyman-α radiation from this galaxy is not yet known, but it is may include the first light from the earliest generation of stars to form in the Universe. Witstok elaborates:
“The large bubble of ionised hydrogen surrounding this galaxy might have been created by a peculiar population of stars — much more massive, hotter and more luminous than stars formed at later epochs, and possibly representative of the first generation of stars”.
A powerful active galactic nucleus (AGN) [3], driven by one of the first supermassive black holes, is another possibility identified by the team.
The new results could not have been obtained without the incredible near-infrared sensitivity of Webb, necessary not only to find such distant galaxies but also to examine their spectra in fine detail. Former NIRSpec Project Scientist, Peter Jakobsen of the Cosmic Dawn Center and the University of Copenhagen in Denmark, recalls:
“Following in the footsteps of the Hubble Space Telescope, it was clear Webb would be capable of finding ever more distant galaxies. As demonstrated by the case of GS-z13-1, however, it was always going to be a surprise what it might reveal about the nature of the nascent stars and black holes that are formed at the brink of cosmic time.”
The team plans further follow-up observations of GS-z13-1, aiming to obtain more information about the nature of this galaxy and origin of its strong Lyman-α radiation. Whatever the galaxy is concealing, it is certain to illuminate a new frontier in cosmology.
This new research has been published today in Nature. The data for this result were captured as part of JADES under JWST programmes #1180 (PI: D. J. Eisenstein), #1210, #1286 and #1287 (PI: N. Luetzgendorf), and the JADES Origin Field programme #3215 (PIs: Eisenstein and R. Maiolino).
The incredibly distant galaxy JADES-GS-z13-1, observed just 330 million years after the Big Bang, was initially discovered with deep imaging from the NASA/ESA/CSA James Webb Space Telescope. Now, an international team of astronomers has definitively identified powerful hydrogen emission from this galaxy at an unexpectedly early period in the Universe’s history, a probable sign that we are seeing some of the first hot stars from the dawn of the Universe. This image shows the location of the galaxy GS-z13-1 in the GOODS-S field, as well as the galaxy itself, imaged with Webb’s Near-Infrared Camera (NIRCam) as part of the JWST Advanced Deep Extragalactic Survey (JADES) programme. These data from NIRCam allowed researchers to identify GS-z13-1 as an incredibly distant galaxy, and to put an estimate on its redshift value. Webb’s unique infrared sensitivity is necessary to observe galaxies at this extreme distance, whose light has been redshifted into infrared wavelengths during its long journey across the cosmos. To confirm the galaxy’s redshift, the team turned to Webb’s Near-Infrared Spectrograph (NIRSpec) instrument. With new observations permitting advanced spectroscopy of the galaxy’s emitted light, the team not only confirmed GS-z13-1’s redshift of 13.0, they also revealed the strong presence of a type of ultraviolet radiation called Lyman-α emission. This is a telltale sign of the presence of newly forming stars, or a possible active galactic nucleus in the galaxy, but at a much earlier time than astronomers had thought possible. The result holds great implications for our understanding of the Universe. Credit: ESA/Webb, NASA & CSA, JADES Collaboration, J. Witstok, P. Jakobsen, A. Pagan (STScI), M. Zamani (ESA/Webb)
Notes
[1] The name comes from the fact that a hydrogen atom emits a characteristic wavelength of light, known as “Lyman-alpha” radiation, that is produced when its electron drops from the second-lowest to the lowest orbit around the nucleus (energy level).
[2] The epoch of reionisation was a very early stage in the Universe’s history that took place after recombination (the first stage following the Big Bang). During recombination, the Universe cooled enough that electrons and protons began to combine to form neutral hydrogen atoms. Reionisation began when denser clouds of gas started to form, creating stars and eventually entire galaxies. They produced large amounts of ultraviolet photons, which gradually reionised the hydrogen gas. As neutral hydrogen gas is opaque to energetic ultraviolet light, we can only see galaxies during this epoch at longer wavelengths until they create a “bubble” of ionised gas around them, so that their ultraviolet light can escape through it and reach us.
[3] An active galactic nucleus is a region of extremely strong radiation at the centre of a galaxy. It is fuelled by an accretion disc, made of material orbiting and falling into a central supermassive black hole. The material crashes together as it spins around the black hole, heating to such extreme temperatures that it radiates highly energetic ultraviolet light and even X-rays, rivalling the brightness of the whole galaxy surrounding it.
Webb captures Neptune’s auroras for the first time
For the first time, the NASA/ESA/CSA James Webb Space Telescope has captured bright auroral activity on Neptune. Auroras occur when energetic particles, often originating from the Sun, become trapped in a planet’s magnetic field and eventually strike the upper atmosphere. The energy released during these collisions creates the signature glow.
In the past, astronomers have seen tantalizing hints of auroral activity on Neptune. However, imaging and confirming the auroras on Neptune has long evaded astronomers despite successful detections on Jupiter, Saturn, and Uranus. Neptune was the missing piece of the puzzle when it came to detecting auroras on the giant planets of our Solar System. Now, Webb’s near-infrared sensitivity has observed this phenomenon.
The data was obtained in June 2023 using Webb’s Near-Infrared Spectrograph. In addition to the image of the planet, astronomers obtained a spectrum to characterise the composition and measure the temperature of the planet’s upper atmosphere (the ionosphere). For the first time, they found an extremely prominent emission line [1] signifying the presence of the trihydrogen cation (H3+), which can be created in auroras. In the Webb images of Neptune, the glowing aurora appears as splotches represented in cyan.
The auroral activity seen on Neptune is noticeably different from what we are accustomed to seeing here on Earth, or even Jupiter or Saturn. Instead of being confined to the planet’s northern and southern poles, Neptune’s auroras are located at the planet’s geographic mid-latitudes — think where South America is located on Earth.
This is due to the strange nature of Neptune’s magnetic field, originally discovered by NASA’s Voyager 2 in 1989, which is tilted by 47 degrees from the planet’s rotation axis. Since auroral activity is based where the magnetic fields converge into the planet’s atmosphere, Neptune’s auroras are far from its rotational poles.
The ground-breaking detection of Neptune’s auroras will help us understand how Neptune’s magnetic field interacts with particles that stream out from the Sun to the distant reaches of our solar system, a totally new window in ice giant atmospheric science.
From the Webb observations, the science team also measured the temperature of the top of Neptune’s atmosphere for the first time since Voyager 2’s flyby. The results hint at why Neptune’s auroras remained hidden from astronomers for so long: Neptune’s upper atmosphere has cooled by several hundreds of degrees.
Through the years, astronomers have predicted the intensity of Neptune’s auroras based on the temperature recorded by Voyager 2. A substantially colder temperature would result in much fainter auroras. This cold temperature is likely the reason that Neptune’s auroras have remained undetected for so long. The dramatic cooling also suggests that this region of the atmosphere can change greatly even though the planet sits over 30 times farther from the Sun compared to Earth.
Equipped with these new findings, astronomers now hope to study Neptune with Webb over a full solar cycle, an 11-year period of activity driven by the Sun’s magnetic field. Results could provide insights into the origin of Neptune’s bizarre magnetic field, and even explain why it’s so tilted.
These observations were obtained as part of Guaranteed Time Observations in programme 1249 (PI: L. Fletcher). The team’s results have been published in Nature Astronomy.
Notes
[1] A bright line in a spectrum caused by emission of light. Each chemical element emits and absorbs radiated energy at specific wavelengths. The collection of emission lines in a spectrum corresponds to the chemical elements contained in a celestial object.
At the left, an enhanced-color image of Neptune from the NASA/ESA Hubble Space Telescope. At the right, that image is combined with data from the NASA/ESA/CSA James Webb Space Telescope. The cyan splotches, which represent auroral activity, and white clouds, are data from Webb’s Near-Infrared Spectrograph (NIRSpec), overlaid on top of the full image of the planet from Hubble’s Wide Field Camera 3. Auroras occur when energetic particles, often originating from the Sun, become trapped in a planet’s magnetic field and eventually strike the upper atmosphere. The energy released during these collisions creates the signature glow. Webb’s detection of auroras on Neptune is the first time astronomers have captured direct evidence of this phenomenon on the planet most distant from the Sun. In addition to the visible glow in the imagery, the spectrum from Webb also found an extremely prominent emission line signifying the presence of the trihydrogen cation (H3+), which can be created in auroras. Neptune’s auroras do not occur at the northern and southern poles of the planet, where we see auroras on planets like Earth and Jupiter, because of the strange nature of Neptune’s magnetic field, which is tilted by 47 degrees from the planet’s rotational axis. Webb’s study of Neptune also revealed that the planet’s upper atmosphere has cooled by several hundred degrees, likely the reason that Neptune’s auroras have remained undetected for so long. This image was created from Hubble and Webb data from proposals: 17187 (R. Windhorst) and 1249 (B. Frye). Credit: NASA, ESA, CSA, STScI, Heidi Hammel (AURA), Henrik Melin (Northumbria University), Leigh Fletcher (University of Leicester), Stefanie Milam (NASA-GSFC)
Webb unmasks true nature of Herbig-Haro 49/50, the Cosmic Tornado
Webb’s exquisite details reveal a chance, random alignment of a protostellar outflow and a distant spiral galaxy.
The NASA/ESA/CSA James Webb Space Telescope has captured a beautiful juxtaposition of the nearby protostellar outflow known as Herbig-Haro 49/50 with a perfectly positioned, more distant spiral galaxy. Due to the close proximity of this Herbig-Haro object to the Earth, this new composite infrared image of the outflow from a young star allows researchers to examine details on small spatial scales like never before. With Webb, we can better understand how the jet activity associated with the formation of young stars can affect their surrounding environment.
The NASA/ESA/CSA James Webb Space Telescope observed Herbig-Haro 49/50, an outflow from a nearby still-forming star, in high-resolution near- and mid-infrared light with the NIRCam and MIRI instruments. The intricate features of the outflow, represented in reddish-orange color, provide detailed clues about how young stars form and how their jet activity affects the environment around them. A chance alignment in this direction of the sky provides a beautiful juxtaposition of this nearby Herbig-Haro object (located within our Milky Way) with a more distant, face-on spiral galaxy in the background. Protostars are young stars in the process of formation that generally launch narrow jets of material. These jets move through the surrounding environment, in some cases extending to large distances away from the protostar. Like the water wake generated by a speeding boat, the arcs in this image are created by the fast-moving jet slamming into surrounding dust and gas. This ambient material is compressed and heats up, then cools by emitting light at visible and infrared wavelengths. In particular, the infrared light captured here by Webb highlights molecular hydrogen and carbon monoxide. The galaxy that appears by happenstance at the tip of Herbig-Haro 49/50 is a much more distant spiral galaxy. It has a prominent central bulge represented in blue that shows the location of older stars. It also displays hints of “side lobes,” suggesting that this could be a barred-spiral galaxy. Reddish clumps within the spiral arms show the locations of warm dust and groups of forming stars. In the image background there are many more galaxies at further distances, including galaxies that shine through the diffuse infrared glow of the nearby Herbig-Haro object. Credit: NASA, ESA, CSA, STScI
This new composite image combines observations from Webb’s NIRCam (Near-Infrared Camera) and MIRI (Mid-Infrared Instrument), which provides a high-resolution view to explore the exquisite details of this bubbling activity. Herbig-Haro 49/50 is located about 630 light-years from Earth in the constellation Chamaeleon.
Herbig-Haro objects are outflows produced by jets launched from a nearby, forming star. The outflows, which can extend for light-years, plow into a denser region of material. This creates shock waves, heating the material to higher temperatures. The material then cools by emitting light at visible and infrared wavelengths.
When NASA’s Spitzer Space Telescope observed it in 2006, scientists nicknamed Herbig-Haro 49/50 (HH 49/50) the “Cosmic Tornado” for its helical appearance, but they were uncertain about the nature of the fuzzy object at the tip of the “tornado.” With its higher imaging resolution, Webb provides a different visual impression of HH 49/50 by revealing fine features of the shocked regions in the outflow, uncovering the fuzzy object to be a distant spiral galaxy, and displaying a sea of distant background galaxies.
HH 49/50 is located in the Chamaeleon I Cloud complex, one of the nearest active star formation regions in our Milky Way, which is creating numerous low-mass stars similar to our Sun. This cloud complex is likely similar to the environment that our Sun formed in. Past observations of this region show that the HH 49/50 outflow is moving away from us at speeds of 100-300 kilometres per second and is just one feature of a larger outflow.
Webb’s NIRCam and MIRI observations of HH 49/50 trace the location of glowing hydrogen molecules, carbon monoxide molecules, and energised grains of dust, represented in orange and red, as the protostellar jet slams into the region. Webb’s observations probe details on small spatial scales that will help astronomers to model the properties of the jet and understand how it is affecting the surrounding material.
The arc-shaped features in HH 49/50, similar to a water wake created by a speeding boat, point back to the source of this outflow. Based on past observations, scientists suspect that a protostar known as Cederblad 110 IRS4 is a plausible driver of the jet activity. Located roughly 1.5 light-years away from HH 49/50 (off the lower right corner of the Webb image), CED 110 IRS4 is a Class I protostar. Class I protostars are young objects (tens of thousands to a million years old) in the prime time of gaining mass. They usually have a discernible disk of material surrounding it that is still falling onto the protostar. Scientists recently used Webb’s NIRCam and MIRI observations to study this protostar and obtain an inventory of the icy composition of its environment.
These detailed Webb images of the arcs in HH 49/50 can more precisely pinpoint the direction to the jet source, but not every arc points back in the same direction. For example, there is an interesting outcrop feature (at the top right of the main outflow) which could be another chance superposition of a different outflow, related to the slow precession of the intermittent jet source. Alternatively, this feature could be a result of the main outflow breaking apart.
The galaxy that appears by happenstance at the tip of HH 49/50 is a much more distant, face-on spiral galaxy. It has a prominent central bulge represented in blue that shows the location of older stars. The bulge also shows hints of “side lobes” suggesting that this could be a barred-spiral galaxy. Reddish clumps within the spiral arms show the locations of warm dust and groups of forming stars. The galaxy even displays evacuated bubbles in these dusty regions, similar to nearby galaxies observed by Webb as part of the PHANGS program.
Webb has captured these two unassociated objects in a lucky alignment. Over thousands of years, the edge of HH 49/50 will move outwards and eventually appear to cover up the distant galaxy.
The NASA/ESA/CSA James Webb Space Telescope observed Herbig-Haro 49/50, an outflow from a nearby still-forming star, in high-resolution near- and mid-infrared light with the NIRCam and MIRI instruments. The intricate features of the outflow, represented in reddish-orange color, provide detailed clues about how young stars form and how their jet activity affects the environment around them. A chance alignment in this direction of the sky provides a beautiful juxtaposition of this nearby Herbig-Haro object (located within our Milky Way) with a more distant, face-on spiral galaxy in the background. Protostars are young stars in the process of formation that generally launch narrow jets of material. These jets move through the surrounding environment, in some cases extending to large distances away from the protostar. Like the water wake generated by a speeding boat, the arcs in this image are created by the fast-moving jet slamming into surrounding dust and gas. This ambient material is compressed and heats up, then cools by emitting light at visible and infrared wavelengths. In particular, the infrared light captured here by Webb highlights molecular hydrogen and carbon monoxide. The galaxy that appears by happenstance at the tip of Herbig-Haro 49/50 is a much more distant spiral galaxy. It has a prominent central bulge represented in blue that shows the location of older stars. It also displays hints of “side lobes,” suggesting that this could be a barred-spiral galaxy. Reddish clumps within the spiral arms show the locations of warm dust and groups of forming stars. In the image background there are many more galaxies at further distances, including galaxies that shine through the diffuse infrared glow of the nearby Herbig-Haro object. Credit: NASA, ESA, CSA, STScI
Findings suggest giant exoplanets in HR 8799 system likely formed like Jupiter and Saturn.
The NASA/ESA/CSA James Webb Space Telescope has captured direct images of multiple gas giant planets within an iconic planetary system. HR 8799, a young system 130 light-years away, has long been a key target for planet formation studies.
The NASA/ESA/CSA James Webb Space Telescope has provided the clearest look yet at the iconic multi-planet system HR 8799. The observations detected carbon dioxide in each of the planets, which provides strong evidence that the system’s four giant planets formed much like Jupiter and Saturn, by slowly building solid cores that attract gas from within a protoplanetary disk. Colours are applied to filters from Webb’s NIRCam (Near-Infrared Camera), revealing their intrinsic differences. A star symbol marks the location of the host star HR 8799, whose light has been blocked by a coronagraph. The colours in this image, which represent different wavelengths captured by Webb’s NIRCam, tell researchers about the temperatures and composition of the planets. HR 8799 b, which orbits around 10.1 billion kilometres from the star, is the coldest of the bunch, and the richest in carbon dioxide. HR 8799 e orbits 2.4 billion kilometres from its star, and likely formed closer to the host star, where there were stronger variations in the composition of material. In this image, the colour blue is assigned to 4.1 micron light, green to 4.3 micron light, and red to the 4.6 micron light. Credit: NASA, ESA, CSA, STScI, W. Balmer (JHU), L. Pueyo (STScI), M. Perrin (STScI)
The observations indicate that the well-studied planets of HR 8799 are rich in carbon dioxide gas. This provides strong evidence that the system’s four giant planets formed much like Jupiter and Saturn, by slowly building solid cores that attract gas from within a protoplanetary disk.
The results also confirm that Webb can infer the chemistry of exoplanet atmospheres through imaging. This technique complements Webb’s powerful spectroscopic instruments, which resolve the atmospheric composition.
“By spotting these strong carbon dioxide features, we have shown there is a sizable fraction of heavier elements, like carbon, oxygen, and iron, in these planets’ atmospheres,” said William Balmer, of Johns Hopkins University in Baltimore. “Given what we know about the star they orbit, that likely indicates they formed via core accretion, which is an exciting conclusion for planets that we can directly see.”
This graph shows a spectrum of one of the planets in the HR 8799 system, HR 8799 e, which displays the amounts of near-infrared light detected from the planet by Webb at different wavelengths. The blue and yellow lines are a best-fit model for an atmosphere that would be either low or high in metals heavier than helium, including carbon, also known as metallicity. The Webb data is consistent with a high metallicity planet. Spectral fingerprints of carbon dioxide and carbon monoxide appear in data collected by Webb’s NIRCam (Near-Infrared Camera). Credit: NASA, ESA, CSA, STScI, W. Balmer (JHU), L. Pueyo (STScI), M. Perrin (STScI)
Balmer is the lead author of the study announcing the results published today in The Astrophysical Journal. Balmer and his team’s analysis also includes Webb’s observation of a system 97 light-years away called 51 Eridani.
HR 8799 is a young system about 30 million years old, a fraction of our solar system’s 4.6 billion years. Still hot from their tumultuous formation, the planets within HR 8799 emit large amounts of infrared light that give scientists valuable data on how they formed.
Giant planets can take shape in two ways: by slowly building solid cores with heavier elements that attract gas, just like the giants in our solar system, or when particles of gas rapidly coalesce into massive objects from a young star’s cooling disk, which is made mostly of the same kind of material as the star. Knowing which formation model is more common can give scientists clues to distinguish between the types of planets they find in other systems.
“Our hope with this kind of research is to understand our own solar system, life, and ourselves in comparison to other exoplanetary systems, so we can contextualize our existence,” Balmer said. “We want to take pictures of other solar systems and see how they’re similar or different when compared to ours. From there, we can try to get a sense of how weird our solar system really is—or how normal.”
Of the nearly 6,000 exoplanets discovered, few have been directly imaged, as even giant planets are many thousands of times fainter than their stars. The images of HR 8799 and 51 Eridani were made possible by Webb’s NIRCam (Near-Infrared Camera) coronagraph, which blocks light from bright stars to reveal otherwise hidden worlds.
The NASA/ESA/CSA James Webb Space Telescope’s NIRCam (Near-Infrared Camera) captured this image of Eridani 51 b, a cool, young exoplanet that orbits 17.7 billion kilometres from its star. Its distance is equivalent to a location between the orbits of Neptune and Saturn in our solar system. The observations detected the planet is rich in carbon dioxide, providing strong evidence that the planet formed much like Jupiter and Saturn, by slowly building a solid core that attracted gas from within a protoplanetary disk. The 51 Eridani system is 96 light-years from Earth. This image includes filters representing 4.1-micron light as red. Credit: NASA, ESA, CSA, STScI, W. Balmer (JHU), L. Pueyo (STScI), M. Perrin (STScI)
This technology allowed the team to look for infrared light emitted by the planets in wavelengths that are absorbed by specific gases. The team found that the four HR 8799 planets contain more heavy elements than previously thought.
“Webb’s unique capabilities are allowing us to explore the wide diversity of these directly-imaged planets for the first time. This gives us important clues as to how such planetary systems have formed.” said Emily Rickman of the European Space Agency, a co-author of the study. “These new observations reiterate how valuable the HR 8799 multi-planet system is as a stepping stone to understand the formation of exoplanetary systems and of our own Solar System.”
The team is paving the way for more detailed observations to determine whether objects they see orbiting other stars are truly giant planets or objects such as brown dwarfs, which form like stars but don’t accumulate enough mass to ignite nuclear fusion.
“We have other lines of evidence that hint at these four HR 8799 planets forming using this bottom-up approach,” said Laurent Pueyo, an astronomer at the Space Telescope Science Institute in Baltimore, who co-led the work. “How common is this for planets we can directly image? We don’t know yet, but we’re proposing more Webb observations to answer that question.”
“We knew Webb could measure colours of the outer planets in directly imaged systems,” added Rémi Soummer, director of STScI’s Russell B. Makidon Optics Lab and former lead for Webb coronagraph operations. “We have been waiting for 10 years to confirm that our finely tuned operations of the telescope would also allow us to access the inner planets. Now the results are in and we can do interesting science with it.”
The NIRCam observations of HR 8799 and 51 Eridani were conducted as part of Guaranteed Time Observations programmes 1194 and 1412 respectively.
Webb wows with incredible detail in actively forming star system, Lynds 483 (L483)
High-resolution near-infrared light captured by the NASA/ESA/CSA James Webb Space Telescope shows extraordinary new detail and structure in Lynds 483 (L483). Two actively forming stars are responsible for the shimmering ejections of gas and dust that gleam in orange, blue, and purple in this representative colour image.
Shimmering ejections emitted by two actively forming stars make up Lynds 483 (L483). High-resolution near-infrared light captured by the NASA/ESA/CSA James Webb Space Telescope shows incredible new detail and structure within these lobes, including asymmetrical lines that appear to run into one another. L483 is 650 light-years away in the constellation Serpens. Credit: NASA, ESA, CSA, STScI
Over tens of thousands of years, the central protostars [1] have periodically ejected some of the gas and dust, spewing it out as tight, fast jets and slightly slower outflows that “trip” across space. When more recent ejections hit older ones, the material can crumple and twirl based on the densities of what is colliding. Over time, chemical reactions within these ejections and the surrounding cloud have produced a range of molecules, like carbon monoxide, methanol, and several other organic compounds.
Dust-encased stars
The two protostars responsible for this scene are at the centre of the hourglass shape, in an opaque horizontal disk of cold gas and dust that fits within a single pixel. Much farther out, above and below the flattened disk where dust is thinner, the bright light from the stars shines through the gas and dust, forming large semi-transparent orange cones.
It’s equally important to notice where the stars’ light is blocked — look for the exceptionally dark, wide V-shapes offset by 90 degrees from the orange cones. These areas may look like there is no material, but it’s actually where the surrounding dust is the densest, and little starlight penetrates it. If you look carefully at these areas, Webb’s sensitive NIRCam (Near-Infrared Camera) has picked up distant stars as muted orange pinpoints behind this dust. Where the view is free of obscuring dust, stars shine brightly in white and blue.
Unraveling the stars’ ejections
Some of the stars’ jets and outflows have wound up twisted or warped. To find examples, look toward the top right edge where there’s a prominent orange arc. This is a shock front, where the stars’ ejections were slowed by existing, denser material.
Now, look a little lower, where orange meets pink. Here, the material looks like a tangled mess. These are new, incredibly fine details Webb has revealed, and will require detailed study to explain.
Turn to the lower half. Here, the gas and dust appear thicker. Zoom in to find tiny light purple pillars. They point toward the central stars’ nonstop winds, and formed because the material within them is dense enough that it hasn’t yet been blown away. L483 is too large to fit in a single Webb snapshot, and this image was taken to fully capture the upper section and outflows, which is why the lower section is only partially shown.
All the symmetries and asymmetries in these clouds may eventually be explained as researchers reconstruct the history of the stars’ ejections, in part by updating models to produce the same effects. Astronomers will also eventually calculate how much material the stars have expelled, which molecules were created when material smashed together, and how dense each area is.
Millions of years from now, when the stars are finished forming, they may each be about the mass of our Sun. Their outflows will have cleared the area — sweeping away these semi-transparent ejections. All that may remain is a tiny disk of gas and dust where planets may eventually form.
L483 is named for American astronomer Beverly T. Lynds, who published extensive catalogues of “dark” and “bright” nebulae in the early 1960s. She did this by carefully examining photographic plates (which preceded film) of the first Palomar Observatory Sky Survey, accurately recording each object’s coordinates and characteristics. These catalogues provided astronomers with detailed maps of dense dust clouds where stars form — critical resources for the astronomical community decades before the first digital files became available and access to the internet was widespread.
This image of protostar Lynds 483 (L483), captured by the NASA/ESA/CSA James Webb Space Telescope’s NIRCam (Near-Infrared Camera), 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 0.1 years for light to travel a distance equal to the length of the scale bar.) One light-year is equal to 9.46 trillion kilometres. This image shows invisible near-infrared wavelengths of light that have been translated into visible-light colours. The colour key shows which NIRCam filters were used when collecting the light. The colour of each filter name is the visible light colour used to represent the infrared light that passes through that filter. Credit: NASA, ESA, CSA, STScI
Notes
[1] A protostar is a collection of interstellar gas and dust whose gravitational pull is causing it to collapse on itself and form a star.
Webb exposes complex atmosphere of SIMP 0136, a starless super-Jupiter
An international team of researchers has discovered that previously observed variations in brightness across a free-floating planetary-mass object known as SIMP 0136 must be the result of a complex combination of atmospheric factors, and cannot be explained by clouds alone.
Using the NASA/ESA/CSA James Webb Space Telescope to monitor a broad spectrum of infrared light emitted by SIMP 0136 over two full rotation periods, the team was able to detect variations in cloud layers, temperature, and carbon chemistry that were previously hidden from view. The results provide crucial insight into the three-dimensional complexity of gas giant atmospheres within and beyond our solar system.
Rapidly rotating, free-floating
SIMP 0136 is a rapidly rotating, free-floating object roughly 13 times the mass of Jupiter, located in the Milky Way just 20 light-years from Earth. Although it is not classified as a gas giant exoplanet — it doesn’t orbit a star and may instead be a brown dwarf — SIMP 0136 is an ideal target for exo-meteorology: It is the brightest object of its kind in the northern sky. Because it is isolated, it can be observed directly and with no fear of light contamination or variability caused by a host star. And its short rotation period of just 2.4 hours makes it possible to survey very efficiently.
Prior to the Webb observations, SIMP 0136 had been studied extensively using ground-based observatories, as well as and NASA’s Spitzer Space Telescope and the NASA/ESA Hubble Space Telescope.
“We already knew that it varies in brightness, and we were confident that there are patchy cloud layers that rotate in and out of view and evolve over time,” explained Allison McCarthy, doctoral student at Boston University and lead author on a study published today in The Astrophysical Journal Letters. “We also thought there could be temperature variations, chemical reactions, and possibly some effects of auroral activity affecting the brightness, but we weren’t sure.”
To figure it out, the team needed Webb’s ability to measure very precise changes in brightness over a broad range of wavelengths.
Charting thousands of infrared rainbows
Using NIRSpec (Near-Infrared Spectrograph), Webb captured thousands of individual 0.6- to 5.3-micron spectra — one every 1.8 seconds over more than three hours as the object completed one full rotation. This was immediately followed by an observation with MIRI (Mid-Infrared Instrument), which collected hundreds of measurements of 5- to 14-micron light — one every 19.2 seconds, over another rotation.
The result was hundreds of detailed light curves, each showing the change in brightness of a very precise wavelength (color) as different sides of the object rotated into view.
“To see the full spectrum of this object change over the course of minutes was incredible,” said principal investigator Johanna Vos, from Trinity College Dublin. “Until now, we only had a little slice of the near-infrared spectrum from Hubble, and a few brightness measurements from Spitzer.”
The team noticed almost immediately that there were several distinct light-curve shapes. At any given time, some wavelengths were growing brighter, while others were becoming dimmer or not changing much at all. A number of different factors must be affecting the brightness variations.
“Imagine watching Earth from far away. If you were to look at each color separately, you would see different patterns that tell you something about its surface and atmosphere, even if you couldn’t make out the individual features,” explained co-author Philip Muirhead, also from Boston University. “Blue would increase as oceans rotate into view. Changes in brown and green would tell you something about soil and vegetation.”
This artist’s concept shows what the isolated planetary-mass object SIMP 0136 could look like based on recent observations from the NASA/ESA/CSA James Webb Space Telescope. SIMP 0136 has a mass about 13 times that of Jupiter. Although it is thought to have the structure and composition of a gas giant, it is not technically classified as an exoplanet because it doesn’t orbit its own star. The colors shown in the illustration represent near-infrared light, which is invisible to human eyes. SIMP 0136 is relatively warm — about 825 degrees Celsius or 1,100 kelvins — but is not hot enough to give off enough visible light to see from Earth, and is not illuminated by a host star. The bluish glow near the poles represents auroral energy (light given off by electrons spiraling in a magnetic field) which has been detected at radio wavelengths. Researchers used NIRSpec (Near-infrared Spectrograph) and MIRI (Mid-Infrared Instrument) to monitor the brightness of SIMP 0136 over two full rotations in July 2023. By analyzing the change in brightness of different wavelengths over time, researchers were able to detect variability in cloud cover at different depths, temperature variations in the high atmosphere, and changes in carbon chemistry as different sides of the object rotated in and out of view. SIMP 0136 is located within the Milky Way, about 20 light-years from Earth, in the constellation Pisces. It is the brightest isolated planet or brown dwarf visible from the Northern Hemisphere, and is thought to be about 200 million years old. This illustration is based on spectroscopic observations. Webb has not captured a direct image of the object. Credit: NASA, ESA, CSA, J. Olmsted (STScI)
Patchy clouds, hot spots, and carbon chemistry
To figure out what could be causing the variability on SIMP 0136, the team used atmospheric models to show where in the atmosphere each wavelength of light was originating.
“Different wavelengths provide information about different depths in the atmosphere,” explained McCarthy. “We started to realize that the wavelengths that had the most similar light-curve shapes also probed the same depths, which reinforced this idea that they must be caused by the same mechanism.”
One group of wavelengths, for example, originates deep in the atmosphere where there could be patchy clouds made of iron particles. A second group comes from higher clouds thought to be made of tiny grains of silicate minerals. The variations in both of these light curves are related to patchiness of the cloud layers.
A third group of wavelengths originates at very high altitude, far above the clouds, and seems to track temperature. Bright “hot spots” could be related to auroras that were previously detected at radio wavelengths, or to upwelling of hot gas from deeper in the atmosphere.
Some of the light curves cannot be explained by either clouds or temperature, but instead show variations related to atmospheric carbon chemistry. There could be pockets of carbon monoxide and carbon dioxide rotating in and out of view, or chemical reactions causing the atmosphere to change.
“We haven’t really figured out the chemistry part of the puzzle yet,” said Vos. “But these results are really exciting because they are showing us that the abundances of molecules like methane and carbon dioxide could change from place to place and over time. If we are looking at an exoplanet and can get only one measurement, we need to consider that it might not be representative of the entire planet.”
This research was conducted as part of Webb’s General Observer (GO) Program 3548.
These light curves show the change in brightness of three different sets of wavelengths (colors) of near-infrared light coming from the isolated planetary-mass object SIMP 0136 as it rotated. The light was captured by Webb’s NIRSpec (Near-Infrared Spectrograph), which collected a total of 5,726 spectra — one every 1.8 seconds — over the course of about 3 hours on 23 July 2023 (SIMP 0136 completes one rotation every 2.4 hours). By comparing these light curves to models, researchers were able to show that each set of wavelengths probes different depths (pressures) in the atmosphere. The curve shown in red tracks the brightness of 0.9- to 1.4-micron light thought to originate deep in the atmosphere at a pressure of about 10 bars (about 10 times the air pressure at sea level on Earth), within clouds made of iron particles. The curve shown in yellow tracks the brightness of 1.4- to 2.3-micron light from a pressure of about 1 bar within higher clouds made of tiny grains of silicate minerals. The variations in brightness shown by these two curves is related to patchiness of the cloud layers, which emit some wavelengths of light and absorb others. The curve shown in blue tracks the brightness of 3.3- to 3.6-micron light that originates high above the clouds at a pressure of about 0.1 bars. Changes in brightness of these wavelengths are related to variations in temperature around the object. Bright “hot spots” could be related to auroras that have been detected at radio wavelengths, or to upwelling of hot gas from deeper in the atmosphere. The differences in shape of these three light curves show that there are complex variations in SIMP 0136’s atmosphere with depth as well as longitude. If the atmosphere varied around the object in the same way at all depths, the light curves would have similar patterns. If it varied with depth, but not longitude, the light curves would be straight, flat lines. Note this graph shows the relative change in brightness for each given set of wavelengths over time, not the difference in absolute brightness between the different sets. At any given time, there is more light coming from the deep atmosphere (red light curve) than from the upper atmosphere (blue light curve). SIMP 0136 is located within the Milky Way, about 20 light-years from Earth, in the constellation Pisces. It is the brightest isolated planet or brown dwarf visible from the Northern Hemisphere, and is thought to be about 200 million years old. The artist’s concepts are based on spectroscopic observations. Webb has not captured a direct image of the object. Credit: NASA, ESA, CSA, J. Olmsted (STScI)
