You can’t judge a star by its protoplanetary disc

Credit: ALMA(ESO/NAOJ/NRAO)/A. Ribas et al.

 

This image tells a story of redemption for a lonely star. The young star MP Mus (PDS 66) was once thought to be all alone in the universe, surrounded by nothing but a featureless band of gas and dust known as a protoplanetary disc. In most cases, the material inside a protoplanetary disc condenses to form new planets around the star, leaving large gaps where the gas and dust used to be. These features are seen in almost every disc — but not in MP Mus’.

When astronomers first observed it with the Atacama Large Millimeter/submillimeter Array (ALMA), they saw a smooth, planet-free disc, shown here in the right image. The team, led by Álvaro Ribas, an astronomer at the University of Cambridge, UK, gave this star another chance and re-observed it with ALMA at longer wavelengths that probe even deeper into the protoplanetary disc than before. These new observations, shown in the left image, revealed a gap and a ring that had been obscured in previous observations, suggesting that MP Mus might have company after all.

Meanwhile, another piece of the puzzle was being revealed in Germany as Miguel Vioque, an astronomer at ESO, studied this same star with the European Space Agency’s (ESA’s) Gaia mission. Vioque noticed something suspicious — the star was wobbling. A bit of gravitational detective work, together with insights from the new disc structures revealed by ALMA, showed that this motion could be explained by the presence of a gas giant exoplanet.

Both teams presented their joint results in a new paper published in Nature Astronomy. In what they describe as “a beautiful merging of two groups approaching the same object from different angles”, they show that MP Mus isn’t so boring after all.

Scientific Paper

Source: ALMA (Atacama Large Millimeter/submillimeter Array)/Science Blog

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Additional information

This text was adapted from a Picture of the Week published by the European Southern Observatory (ESO), an ALMA partner on behalf of Europe.

The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of the European Southern Observatory (ESO), the U.S. National Science Foundation (NSF), and the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Republic of Chile. ALMA is funded by ESO on behalf of its Member States, by NSF in cooperation with the National Research Council of Canada (NRC) and the National Science and Technology Council (NSTC) in Taiwan, and by NINS in cooperation with the Academia Sinica (AS) in Taiwan and the Korea Astronomy and Space Science Institute (KASI).

ALMA construction and operations are led by ESO on behalf of its Member States; by the National Radio Astronomy Observatory (NRAO), managed by Associated Universities, Inc. (AUI), on behalf of North America; and by the National Astronomical Observatory of Japan (NAOJ) on behalf of East Asia. The Joint ALMA Observatory (JAO) provides the unified leadership and management of ALMA's construction, commissioning, and operation.

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Contacts:

Nicolás Lira
Education and Public Outreach Officer
Joint ALMA Observatory, Santiago - Chile
Phone: +56 2 2467 6519
Cel: +56 9 9445 7726
Email: nicolas.lira@alma.cl

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Astronomers spot mysterious gamma-ray explosion, unlike any detected before

PR Image eso2514a
GRB 250702B, an unusually long and repeating gamma-ray burst

PR Image eso2514b
Wider view of the area around the gamma-ray burst GRB 250702B

PR Image eso2514c
Evolution of the gamma-ray burst GRB 250702B

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Videos


PR Video eso2514a
Zooming into an unusually long and repeating explosion


PR Video eso2514b
Time-lapse of the gamma-ray burst GRB 250702B

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Astronomers have detected an explosion of gamma rays that repeated several times over the course of a day, an event unlike anything ever witnessed before. The source of the powerful radiation was discovered to be outside our galaxy, its location pinpointed by the European Southern Observatory’s Very Large Telescope (VLT). Gamma-ray bursts (GRBs) are the most powerful explosions in the Universe, normally caused by the catastrophic destruction of stars. But no known scenario can completely explain this new GRB, whose true nature remains a mystery.

This GRB is “unlike any other seen in 50-years of GRB observations,” according to Antonio Martin-Carrillo, astronomer at University College Dublin, Ireland, and co-lead author of a study on this signal recently published in The Astrophysical Journal Letters.

GRBs are the most energetic explosions in the Universe. They are produced in catastrophic events like massive stars dying in powerful blasts or being ripped apart by black holes, among other events. They usually last milliseconds to minutes, but this signal — GRB 250702B [1] — lasted about a day. "This is 100-1000 times longer than most GRBs,” says Andrew Levan, astronomer at Radboud University, The Netherlands, and co-lead author of the study.

“More importantly, gamma-ray bursts never repeat since the event that produces them is catastrophic,” says Martin-Carrillo. The initial alert about this GRB came on 2 July from NASA’s Fermi Gamma-ray Space Telescope. Fermi detected not one but three bursts from this source over the course of several hours. Retrospectively, it was also discovered that the source had been active almost a day earlier, as seen by the Einstein Probe, an X-ray space telescope mission by the Chinese Academy of Sciences with the European Space Agency (ESA) and the Max Planck Institute for Extraterrestrial Physics. Such a long and repeating GRB has never been seen before

These observations only provided an approximate location for the GRB, which was towards the plane of our galaxy, crowded with stars. Therefore, the team turned to ESO’s VLT to pinpoint the actual source within this area. “Before these observations, the general feeling in the community was that this GRB must have originated from within our galaxy. The VLT fundamentally changed that paradigm,” says Levan, who is also affiliated with the University of Warwick, UK.

Using the VLT’s HAWK-I camera, they found evidence that the source may actually reside in another galaxy. This was later confirmed by the NASA/ESA Hubble Space Telescope. “What we found was considerably more exciting: the fact that this object is extragalactic means that it is considerably more powerful,” says Martin-Carrillo. The size and brightness of the host galaxy suggest it may be located a few billion light-years away, but more data are needed to refine this distance.

The nature of the event that caused this GRB is still unknown. One possible scenario is a massive star collapsing onto itself, releasing vast amounts of energy in the process. “If this is a massive star, it is a collapse unlike anything we have ever witnessed before,” says Levan, as in that case the GRB would have lasted just a few seconds. Alternatively, a star being ripped apart by a black hole could produce a day-long GRB, but to explain other properties of the explosion would require an unusual star being destroyed by an even more unusual black hole. [2]

To learn more about this GRB, the team has been monitoring the aftermath of the explosion with different telescopes and instruments, including the VLT’s X-shooter spectrograph and the James Webb Space Telescope, a joint project of NASA, ESA and the Canadian Space Agency. Finding that this explosion took place in another galaxy will be key to deciphering what caused it. “We are still not sure what produced this, but with this research we have made a huge step forward towards understanding this extremely unusual and exciting object,” says Martin-Carrillo.

Source: ESO/News

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Notes

[1] Also known as GRB 250702BDE. GRBs are named with a number denoting the date when they were detected, followed by a letter if more than one burst was found that day. Bursts B, D and E are all linked to the same object.

[2] The authors favour a scenario in which a white dwarf was shredded by a so-called intermediate-mass black hole. A white dwarf is the small, slowly-cooling core that is left behind after a star like our Sun dies. Intermediate-mass black holes are between 100 and 100 000 times more massive than the Sun. Most known black holes have masses significantly greater or lower than that, and intermediate-mass black holes remain a poorly understood type of object.

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More information

This research was presented in the paper "The day long, repeating GRB 250702B: A unique extragalactic transient" (doi: https://doi.org/10.3847/2041-8213/adf8e1) published in The Astrophysical Journal Letters.

The team is composed of A. J. Levan (Department of Astrophysics/IMAPP, Radboud University, The Netherlands [Radboud]), A. Martin-Carrillo (School of Physics and Centre for Space Research, University College Dublin, Ireland [UCD]), T. Laskar (Department of Physics & Astronomy, University of Utah, USA), R. A. J. Eyles-Ferris (School of Physics and Astronomy, University of Leicester, UK [Leicester]), A. Sneppen (Niels Bohr Institute, University of Copenhagen [NBI] and The Cosmic Dawn Centre [DAWN], Denmark), M. E. Ravasio (Radboud and INAF-Osservatorio Astronomico di Brera, Italy [INAF-Brera]), J. C. Rastinejad (Center for Interdisciplinary Exploration and Research in Astrophysics [CIERA] and Department of Physics and Astronomy, Northwestern University, USA), J. S. Bright (Astrophysics, Department of Physics, University of Oxford, UK), F. Carotenuto (INAF-Osservatorio Astronomico di Roma, Italy [INAF-Roma]), A. A. Chrimes (European Space Agency [ESA], European Space Research and Technology Centre [ESTEC], The Netherlands, and Radboud), G. Corcoran (UCD), B. P. Gompertz (School of Physics and Astronomy and Institute for Gravitational Wave Astronomy, University of Birmingham, UK [UBham]), P. G. Jonker (Radboud), G. P. Lamb (Astrophysics Research Institute, Liverpool John Moores University, UK), D. B. Malesani (NBI and DAWN), A. Saccardi (Université Paris-Saclay, Université Paris Cité, CEA, CNRS, France), J. Sánchez-Sierras (Radboud), B. Schneider (Aix Marseille Univ., CNRS, CNES, LAM, France [amU]), S. Schulze (CIERA), N. R. Tanvir (Leicester), S. D. Vergani (LUX, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, France), D. Watson (NIB and DAWN), J. An (National Astronomical Observatories, Chinese Academy of Sciences [NAOC] and School of Astronomy and Space Science, University of Chinese Academy of Sciences, Chinese Academy of Sciences, China), F. E. Bauer (Instituto de Alta Investigación, Universidad de Tarapacá, Chile), S. Campana (INAF-Brera), L. Cotter (UCD), J. N. D. van Dalen (Radboud), V. D’Elia (Space Science Data Center - Agenzia Spaziale Italiana, Italy), M. De Pasquale (MIFT Department, University of Messina, Italy), A. de Ugarte Postigo (amU), Dimple (UBham), D. H. Hartmann (Clemson University, Department of Physics and Astronomy, USA), J. Hjorth (DARK, NIB), L. Izzo (INAF, Osservatorio Astronomico di Capodimonte, Italy and DARK, NIB), P. Jakobsson (Centre for Astrophysics and Cosmology, Science Institute, University of Iceland, Iceland), A. Kumar (Department of Physics, Royal Holloway - University of London, UK), A. Melandri (INAF-Roma), P. O’Brien (Leicester), S. Piranomonte (INAF-Roma), G. Pugliese (Anton Pannekoek Institute of Astronomy, University of Amsterdam, The Netherlands), J. Quirola-Vásquez (Radboud), R. Starling (Leicester), G. Tagliaferri (INAF-Brera), D. Xu (NAOC) and M. E. Wortley (UBham).

The European Southern Observatory (ESO) enables scientists worldwide to discover the secrets of the Universe for the benefit of all. We design, build and operate world-class observatories on the ground — which astronomers use to tackle exciting questions and spread the fascination of astronomy — and promote international collaboration for astronomy. Established as an intergovernmental organisation in 1962, today ESO is supported by 16 Member States (Austria, Belgium, Czechia, Denmark, France, Finland, Germany, Ireland, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom), along with the host state of Chile and with Australia as a Strategic Partner. ESO’s headquarters and its visitor centre and planetarium, the ESO Supernova, are located close to Munich in Germany, while the Chilean Atacama Desert, a marvellous place with unique conditions to observe the sky, hosts our telescopes. ESO operates three observing sites: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope and its Very Large Telescope Interferometer, as well as survey telescopes such as VISTA. Also at Paranal, ESO will host and operate the south array of the Cherenkov Telescope Array Observatory, the world’s largest and most sensitive gamma-ray observatory. Together with international partners, ESO operates ALMA on Chajnantor, a facility that observes the skies in the millimetre and submillimetre range. At Cerro Armazones, near Paranal, we are building “the world’s biggest eye on the sky” — ESO’s Extremely Large Telescope. From our offices in Santiago, Chile we support our operations in the country and engage with Chilean partners and society.

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Links

• Research paper
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Contacts:

Andrew Levan
Department of Astrophysics, Radboud University
Nijmegen, The Netherlands
Email: a.levan@astro.ru.nl

Antonio Martin-Carrillo
School of Physics and Centre for Space Research, University College Dublin
Dublin, Ireland
Email: antonio.martin-carrillo@ucd.ie

Bárbara Ferreira
ESO Media Manager
Garching bei München, Germany
Tel: +49 89 3200 6670
Cell: +49 151 241 664 00
Email: press@eso.org

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NASA Webb Looks at Earth-Sized, Habitable-Zone Exoplanet TRAPPIST-1 e

Trappist-1 e (Artist's Concept)

The Earth-size exoplanet TRAPPIST-1 e, depicted at the lower right, is silhouetted as it passes in front of its flaring host star in this artist’s concept of the TRAPPIST-1 system. Scientists call this event a transit, when valuable data can be gathered as the exoplanet passes between the star and the telescope and starlight illuminates the atmosphere, if one is present. NASA’s James Webb Space Telescope has made initial observations of planets b, c, d, and e during their transits, with additional observations of planet e underway. While the star’s frequent flares make it difficult to detect an atmosphere, each transit builds up more and more information for scientists to get a more complete picture of these distant worlds. Credits/Artwork: NASA, ESA, CSA, STScI, Joseph Olmsted (STScI)

TRAPPIST-1 e Transmission Spectrum (NIRSpec)

This transmission spectrum graph compares data collected by the NIRSpec (Near-Infrared Spectrograph) instrument on NASA’s James Webb Space Telescope with computer models of exoplanet TRAPPIST-1 e with (blue) and without (orange) an atmosphere. Narrower, darker colored bands show the most likely locations of data points for each model while wider, more transparent bands show areas that are less likely but still permitted by the models. The gray region shows where those two models overlap. Researchers can’t yet confidently rule out an atmosphere since many of the data points fit either scenario. As Webb makes additional observations of the exoplanet, researchers will be able to further refine and characterize the atmospheric readings. However, the existing data does indicate that the exoplanet does not have a thick, hydrogen-rich atmosphere because multiple prominent spikes would be detectable if hydrogen were present. Credits/Illustration: NASA, ESA, CSA, STScI, Joseph Olmsted (STScI)

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Scientists are in the midst of observing the exoplanet TRAPPIST-1 e with NASA’s James Webb Space Telescope. Careful analysis of the results so far presents several potential scenarios for what the planet’s atmosphere and surface may be like, as NASA science missions lay key groundwork to answer the question, “are we alone in the universe?”

“Webb’s infrared instruments are giving us more detail than we’ve ever had access to before, and the initial four observations we’ve been able to make of planet e are showing us what we will have to work with when the rest of the information comes in,” said Néstor Espinoza of the Space Telescope Science Institute in Baltimore, Maryland, a principal investigator on the research team. Two scientific papers detailing the team’s initial results are published in the Astrophysical Journal Letters.

Of the seven Earth-sized worlds orbiting the red dwarf star TRAPPIST-1, planet e is of particular interest because it orbits the star at a distance where water on the surface is theoretically possible — not too hot, not too cold — but only if the planet has an atmosphere. That’s where Webb comes in. Researchers aimed the telescope’s powerful NIRSpec (Near-Infrared Spectrograph) instrument at the system as planet e transited, or passed in front of, its star. Starlight passing through the planet’s atmosphere, if there is one, will be partially absorbed, and the corresponding dips in the light spectrum that reaches Webb will tell astronomers what chemicals are found there. With each additional transit, the atmospheric contents become clearer as more data is collected.

Primary atmosphere unlikely

Though multiple possibilities remain open for planet e because only four transits have been analyzed so far, the researchers feel confident that the planet does not still have its primary, or original, atmosphere. TRAPPIST-1 is a very active star, with frequent flares, so it is not surprising to researchers that any hydrogen-helium atmosphere with which the planet may have formed would have been stripped off by stellar radiation. However many planets, including Earth, build up a heavier secondary atmosphere after losing their primary atmosphere. It is possible that planet e was never able to do this and does not have a secondary atmosphere. Yet researchers say there is an equal chance there is an atmosphere, and the team developed novel approaches to working with Webb’s data to determine planet e’s potential atmospheres and surface environments.

World of (fewer) possibilities

The researchers say it is unlikely that the atmosphere of TRAPPIST-1 e is dominated by carbon dioxide, analogous to the thick atmosphere of Venus and the thin atmosphere of Mars. However, the researchers also are careful to note that there are no direct parallels with our solar system.

"TRAPPIST-1 is a very different star from our Sun, and so the planetary system around it is also very different, which challenges both our observational and theoretical assumptions,” said team member Nikole Lewis, an associate professor of astronomy at Cornell University.

If there is liquid water on TRAPPIST-1 e, the researchers say it would be accompanied by a greenhouse effect, in which various gases, particularly carbon dioxide, keep the atmosphere stable and the planet warm.

“A little greenhouse effect goes a long way,” said Lewis, and the measurements do not rule out adequate carbon dioxide to sustain some water on the surface. According to the team’s analysis, the water could take the form of a global ocean, or cover a smaller area of the planet where the star is at perpetual noon, surrounded by ice. This would be possible because, due to the TRAPPIST-1 planets’ sizes and close orbits to their star, it is thought that they all are tidally locked, with one side always facing the star and one side always in darkness.

Innovative new method

Espinoza and co-principal investigator Natalie Allen of Johns Hopkins University are leading a team that is currently making 15 additional observations of planet e, with an innovative twist. The scientists are timing the observations so that Webb catches both planets b and e transiting the star one right after the other. After previous Webb observations of planet b, the planet orbiting closest to TRAPPIST-1, scientists are fairly confident it is a bare rock without an atmosphere. This means that signals detected during planet b’s transit can be attributed to the star only, and because planet e transits at nearly the same time, there will be less complication from the star’s variability. Scientists plan to compare the data from both planets, and any indications of chemicals that show up only in planet e’s spectrum can be attributed to its atmosphere.

“We are really still in the early stages of learning what kind of amazing science we can do with Webb. It’s incredible to measure the details of starlight around Earth-sized planets 40 light-years away and learn what it might be like there, if life could be possible there,” said Ana Glidden, a post-doctoral researcher at Massachusetts Institute of Technology’s Kavli Institute for Astrophysics and Space Research, who led the research on possible atmospheres for planet e. “We’re in a new age of exploration that’s very exciting to be a part of,” she said.

The four transits of TRAPPIST-1 e analyzed in the new papers published today were collected by the JWST Telescope Scientist Team’s DREAMS (Deep Reconnaissance of Exoplanet Atmospheres using Multi-instrument Spectroscopy) collaboration.

The James Webb Space Telescope is the world’s premier space science observatory. Webb is solving mysteries in our solar system, looking beyond to distant worlds around other stars, and probing the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners, ESA (European Space Agency) and CSA (Canadian Space Agency).

Source: NASA's James Webb Space Telescope/News

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About This Release

Credits:

Media Contact

Leah Ramsay
Space Telescope Science Institute, Baltimore

Hannah Braun
Space Telescope Science Institute, Baltimore

Permissions: Content Use Policy

Contact Us: Direct inquiries to the News Team.

Related Links and Documents

• The science paper by N. Espinoza et al.
• The science paper by A. Glidden et al.
• JWST Telescope Science Team

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Cloudy cluster

Stars in a star cluster shine brightly blue, with four-pointed spikes radiating from them. The centre shows a small, crowded group of stars while a larger group lies out of view on the left. The nebula is mostly thick, smoky clouds of gas, lit up in blue tones by the stars. Clumps of dust hover before and around the stars; they are mostly dark, but lit around their edges where the starlight erodes them. Credit: ESA/Hubble & NASA, C. Murray, J. Maíz Apellániz. Large JPEG

This new NASA/ESA Hubble Space Telescope Picture of the Week features a cloudy starscape from an impressive star cluster. This scene is located in the Large Magellanic Cloud, a dwarf galaxy situated about 160 000 light-years away in the constellations Dorado and Mensa. With a mass equal to 10–20% of the mass of the Milky Way, the Large Magellanic Cloud is the largest of the dozens of small galaxies that orbit our galaxy.

The Large Magellanic Cloud is home to several massive stellar nurseries where gas clouds, like those strewn across this image, coalesce into new stars. Today’s image depicts a portion of the galaxy’s second-largest star-forming region, which is called N11. (The most massive and prolific star-forming region in the Large Magellanic Cloud, the Tarantula Nebula, is a frequent target for Hubble.) We see bright, young stars lighting up the gas clouds and sculpting clumps of dust with powerful ultraviolet radiation.

This image marries observations made roughly 20 years apart, a testament to Hubble’s longevity. The first set of observations, which were carried out in 2002–2003, capitalised on the exquisite sensitivity and resolution of the then-newly-installed Advanced Camera for Surveys. Astronomers turned Hubble toward the N11 star cluster to do something that had never been done before at the time: catalogue all the stars in a young cluster with masses between 10% of the Sun’s mass and 100 times the Sun’s mass.

The second set of observations came from Hubble’s newest camera, the Wide Field Camera 3. These images focused on the dusty clouds that suffuse the cluster, bringing a new perspective on cosmic dust.

Source: ESA/Hubble/potw

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Dusty wisps round a dusty disc

A wide-field image of IRAS 16594-4656 taken by the James Webb Space Telescope. The nebula’s bright core is split by a narrow dark band, with expansive rainbow lobes of light and colour radiating outward. Numerous background galaxies and stars are visible across the field. redit: ESA/Webb, NASA & CSA, M. Villenave et al. Hi-rs image

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

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

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

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

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

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

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

Source: ESA/Webb/potm

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Links:

• Close-up view of IRAS 04302+2247
• Science paper (M. Villenave et al.)
• Pan video
• Image on ESA website

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Glittering Glimpse of Star Birth From NASA's Webb Telescope

Pismis 24 (NIRCam Image)

Webb captured this sparkling scene of star birth in Pismis 24, a young star cluster about 5,500 light-years from Earth in the constellation Scorpius. This region is one of the best places to explore the properties of hot young stars and how they evolve. Read the full image description. Credits/Image: NASA, ESA, CSA, STScI. Image Processing: Alyssa Pagan (STScI)

Pismis 24 (NIRCam Compass Image)

This image of Pismis 24, also called NGC 6357, was captured by the James Webb Space Telescope’s NIRCam (Near-Infrared Camera). For reference, it shows compass arrows, scale bar, and color key. 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 to the direction arrows on a map of the ground (as seen from above). The scale bar is labeled 1 light-year, which is the distance that light travels in one Earth-year. (One light-year is equal to about 5.88 trillion miles or 9.46 trillion kilometers.) This image shows invisible near-infrared wavelengths of light that have been translated into visible-light colors. The color key shows which NIRCam filters were used when collecting the light. The color of each filter name is the visible light color used to represent the infrared light that passes through that filter. Credits/Image: NASA, ESA, CSA, STScI. Image Processing: Alyssa Pagan (STScI)

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Expedition to Star Cluster Pismis 24
Credits/Video: NASA, ESA, CSA, STScI, Leah Hustak (STScI), Christian Nieves (STScI)
Image Processing: Alyssa Pagan (STScI) - Script Writer: Frank Summers (STScI)
Narration: Frank Summers (STScI) - Music: Christian Nieves (STScI)
Audio: Danielle Kirshenblat (STScI) - Producer: Greg Bacon (STScI) - Acknowledgment: VISTA

Zoom to Pismis 24

 Credits/Video: NASA, ESA, CSA, STScI, Alyssa Pagan (STScI) - Narration: Frank Summers (STScI)
Script Writer: Frank Summers (STScI) - Music: Christian Nieves (STScI) - Audio: Danielle Kirshenblat (STScI)
Producer: Greg Bacon (STScI) - Acknowledgment: VISTA, Akira Fujii, DSS

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This is a sparkling scene of star birth captured by NASA’s James Webb Space Telescope. What appears to be a craggy, starlit mountaintop kissed by wispy clouds is actually a cosmic dust-scape being eaten away by the blistering winds and radiation of nearby, massive, infant stars.

Called Pismis 24, this young star cluster resides in the core of the nearby Lobster Nebula, approximately 5,500 light-years from Earth in the constellation Scorpius. Home to a vibrant stellar nursery and one of the closest sites of massive star birth, Pismis 24 provides rare insight into large and massive stars. Its proximity makes this region one of the best places to explore the properties of hot young stars and how they evolve.

At the heart of this glittering cluster is the brilliant Pismis 24-1. It is at the center of a clump of stars above the jagged orange peaks, and the tallest spire is pointing directly toward it. Pismis 24-1 appears as a gigantic single star, and it was once thought to be the most massive known star. Scientists have since learned that it is composed of at least two stars, though they cannot be resolved in this image. At 74 and 66 solar masses, respectively, the two known stars are still among the most massive and luminous stars ever seen.

Captured in infrared light by Webb’s NIRCam (Near-Infrared Camera), this image reveals thousands of jewel-like stars of varying sizes and colors. The largest and most brilliant ones with the six-point diffraction spikes are the most massive stars in the cluster. Hundreds to thousands of smaller members of the cluster appear as white, yellow, and red, depending on their stellar type and the amount of dust enshrouding them. Webb also shows us tens of thousands of stars behind the cluster that are part of the Milky Way galaxy.

Super-hot, infant stars –some almost 8 times the temperature of the Sun – blast out scorching radiation and punishing winds that are sculpting a cavity into the wall of the star-forming nebula. That nebula extends far beyond NIRCam’s field of view. Only small portions of it are visible at the bottom and top right of the image. Streamers of hot, ionized gas flow off the ridges of the nebula, and wispy veils of gas and dust, illuminated by starlight, float around its towering peaks.

Dramatic spires jut from the glowing wall of gas, resisting the relentless radiation and winds. They are like fingers pointing toward the hot, young stars that have sculpted them. The fierce forces shaping and compressing these spires cause new stars to form within them. The tallest spire spans about 5.4 light-years from its tip to the bottom of the image. More than 200 of our solar systems out to Neptune’s orbit could fit into the width its tip, which is 0.14 lightyears.

In this image, the color cyan indicates hot or ionized hydrogen gas being heated up by the massive young stars. Dust molecules similar to smoke here on Earth are represented in orange. Red signifies cooler, denser molecular hydrogen. The darker the red, the denser the gas. Black denotes the densest gas, which is not emitting light. The wispy white features are dust and gas that are scattering starlight.

The James Webb Space Telescope is the world’s premier space science observatory. Webb is solving mysteries in our solar system, looking beyond to distant worlds around other stars, and probing the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners, ESA (European Space Agency) and CSA (Canadian Space Agency).

Source: NASA's James Webb Space Telescope/News

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About This Release

Credits:

Media Contact

Ann Jenkins
Space Telescope Science Institute, Baltimore

Christine Pulliam
Space Telescope Science Institute, Baltimore

Permissions: Content Use Policy

Contact Us: Direct inquiries to the News Team.

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Gemini South Captures Growing Tail of Interstellar Comet 3I/ATLAS During Educational Observing Program

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Growing Tail of Interstellar Comet 3I/ATLAS

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Growing Tail of Interstellar Comet 3I/ATLAS

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Videos


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Growing Tail of Interstellar Comet 3I/ATLAS


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Growing Tail of Interstellar Comet 3I/ATLAS

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New images of the famous interstellar visitor were captured live from the Gemini South telescope control room in Chile during Shadow the Scientists program

Astronomers and students working together through a unique educational initiative have obtained a striking new image of the growing tail of interstellar Comet 3I/ATLAS. The observations reveal a prominent tail and glowing coma from this rare celestial visitor, while also providing new scientific measurements of its colors and composition.

On 27 August 2025, researchers used the Gemini Multi-Object Spectrograph (GMOS) on Gemini South at Cerro Pachón in Chile to obtain deep, multi-color images of interstellar comet Comet 3I/ATLAS. Gemini South is one half of the International Gemini Observatory, partly funded by the U.S. National Science Foundation (NSF) and operated by NSF NOIRLab.

These observations were taken as part of a public outreach initiative organized by NSF NOIRLab in collaboration with Shadow the Scientists, an initiative created to connect the public with scientists to engage in authentic scientific experiments, such as astronomy observing experiences on world-class telescopes [1]. The scientific program was led by Karen Meech, astronomer at the University of Hawai‘i Institute for Astronomy (UH IfA) [2].

In the images captured during the session [3], the comet displays a broad coma — a cloud of gas and dust that forms around the comet’s icy nucleus as it gets closer to the Sun — and a tail spanning about 1/120th of a degree in the sky (where one degree is about the width of a pinky finger on an outstretched arm) and pointing away from the Sun. These features are significantly more extended than they appeared in earlier images of the comet, showing that 3I/ATLAS has become more active as it travels through the inner Solar System.

Members of the public, including students from Hawai‘i and La Serena, Chile, were invited to remotely join the Gemini South control room in a special two-hour Zoom session where they could interact directly with astronomers, ask questions about interstellar cometary science, and follow the progress of the observations in real time. The event was followed across the world with people joining from Europe, New Zealand, and South America.

More than just capturing stunning images, the main scientific motivation of the observing session was to collect the comet’s spectrum, which refers to the wavelengths of light that it emits. A spectrum can tell scientists information about the comet's composition and chemistry, which allows them to understand how the comet changes as it passes through the Solar System.

The interstellar object was first detected on 1 July 2025 by ATLAS (Asteroid Terrestrial-impact Last Alert System). The new observations suggest that the dust and ice of 3I/ATLAS are broadly similar to those of comets native to our Solar System, hinting at shared processes in the formation of planetary systems around other stars.

During the observing session, Bin Yang, assistant professor at the Instituto de Estudios Astrofísicos (IEA) at Universidad Diego Portales, guided participants through the interpretation of the spectral data, while Meech led a discussion about the importance of interstellar objects for understanding the formation and evolution of planetary systems.

“The primary objectives of the observations were to look at the colors of the comet, which provide clues to the composition and sizes of the dust particles in the coma, and to take spectra for a direct measure of the chemistry,” says Meech. “We were excited to see the growth of the tail, suggesting a change in the particles from the previous Gemini images, and we got our first glimpse of the chemistry from the spectrum.”

Interstellar comets are extraordinarily rare: 3I/ATLAS is only the third confirmed example after Comet 1I/ʻOumuamua in 2017 and Comet 2I/Borisov in 2019. Unlike comets bound to the Sun, 3I/ATLAS is traveling on a hyperbolic orbit that will eventually carry it back into interstellar space. Its brief passage through the Solar System gives astronomers a once-in-a-lifetime opportunity to study material that formed around a distant star.

This effort builds on NOIRLab’s tradition of combining cutting-edge science with public engagement, ensuring that remarkable cosmic events are shared as widely as possible. By involving learners directly in observing sessions and data collection, programs like this one not only advance knowledge but also inspire the next generation of explorers.

“As 3I/ATLAS speeds back into the depths of interstellar space, this image is both a scientific milestone and a source of wonder,” says Meech. “It reminds us that our Solar System is just one part of a vast and dynamic galaxy — and that even the most fleeting visitors can leave a lasting impact.”

Also present during the observing session and lending his scientific expertise was Bryce Bolin, research scientist from Eureka Scientific. “These observations provide both a breathtaking view and critical scientific data,” he says. “Every interstellar comet is a messenger from another star system, and by studying their light and color, we can begin to understand the diversity of worlds beyond our own.” In November 2025, when Comet 3I/ATLAS reemerges from behind the Sun, Bolin will host a follow-up Shadow the Scientists observing session, this time bringing the public into the control room of the Gemini North telescope in Hawai‘i [4].

Source: NSF’s National Optical-Infrared Astronomy Research Laboratory (NOIRLab)/News

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Notes

[1] The Shadow the Scientists initiative is made possible through the Creating Equity in STEAM (CrEST) program at the University of California, Santa Cruz, as well as support from the Heising-Simons Foundation.

[2] The observing strategy for the session was planned by Karen Meech, Bin Yang, assistant professor at the Instituto de Estudios Astrofísicos (IEA) at Universidad Diego Portales, and Jan Kleyna, a postdoctoral scholar at UH IfA.

[3] All data are available for download from the Gemini Archive. A full recording of the session can be found here.

[4] When available, information about this session will be posted here.

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More information

NSF NOIRLab, the U.S. National Science Foundation center for ground-based optical-infrared astronomy, operates the International Gemini Observatory (a facility of NSF, NRC–Canada, ANID–Chile, MCTIC–Brazil, MINCyT–Argentina, and KASI–Republic of Korea), NSF Kitt Peak National Observatory (KPNO), NSF Cerro Tololo Inter-American Observatory (CTIO), the Community Science and Data Center (CSDC), and NSF–DOE Vera C. Rubin Observatory (in cooperation with DOE’s SLAC National Accelerator Laboratory). It is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with NSF and is headquartered in Tucson, Arizona.

The scientific community is honored to have the opportunity to conduct astronomical research on I’oligam Du’ag (Kitt Peak) in Arizona, on Maunakea in Hawai‘i, and on Cerro Tololo and Cerro Pachón in Chile. We recognize and acknowledge the very significant cultural role and reverence of I’oligam Du’ag to the Tohono O’odham Nation, and Maunakea to the Kanaka Maoli (Native Hawaiians) community.

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Links

• Explore Gemini South’s image of Comet 3I/ATLAS in more detail
• Shadow the Scientists webpage
• Gemini North Observes Comet 3I/ATLAS 15 July 2025
• Check out other NOIRLab Photo Releases

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Contacts:

Karen Meech
Astronomer
University of Hawai‘i Institute for Astronomy
Email: meech@hawaii.edu

Josie Fenske
Public Information Officer
NSF NOIRLab
Email: josie.fenske@noirlab.edu

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Neighboring Star’s Warped Ring Shaped by Evolving Planets

The bright star in the center, Fomalhaut, is surrounded by an ancient debris disk of uneven brightness. The disk is closer to the star in the south, where the disk is wider and fainter, and further from the star in the north, where the disk is narrower and brighter. The dotted ring shows the possible orbit of a planet implied by Lovell et al. Credit: NSF/AUI/NSF NRAO/B.Saxton. Hi-Res File

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Unusual shape of Fomalhaut’s debris ring shows evidence of sculpting by ancient planets, rewriting story of planetary system evolution

Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) have made the highest resolution image to date, revealing new insights into the unusual and mysterious architecture of the debris disk encircling Fomalhaut, one of the brightest and most well-studied stars in our cosmic neighborhood. Debris disks are vast belts of dust and rocky bodies, similar to our Solar System’s asteroid belt—but much larger. The lopsidedness (or eccentricity) of Fomalhaut’s disk has fascinated astronomers for nearly two decades.

An international research team, led by astronomers at the Center for Astrophysics | Harvard & Smithsonian and Johns Hopkins University, published two papers analyzing these new observations in the Astrophysical Journal/Astrophysical Journal Letters. They have now found that Fomalhaut’s disk is not just eccentric—its eccentricity changes with distance from the star. Unlike previous models assuming a uniform or “fixed” eccentricity, their new data-driven model shows that the disk’s shape grows less stretched (or less eccentric) the farther a segment is from Fomalhaut. This morphology is known as a negative eccentricity gradient. You can imagine the offsets between the star and the ring’s center, much like Saturn’s rings, if Saturn wasn’t sitting neatly in the middle.

“Our observations show, for the first time, that the disk’s eccentricity isn’t constant,” said lead author of one of the papers, Joshua Bennett Lovell, a Submillimeter Array Fellow with the Harvard-Smithsonian Center for Astrophysics. “It steadily drops off with distance, a finding that has never before been conclusively demonstrated in any debris disk.” Lovell is also an ALMA Ambassador with the U.S. National Science Foundation National Radio Astronomy Observatory’s North American ALMA Science Center.

Using high-resolution ALMA images at 1.3mm wavelengths, the team fitted a new model setup to the data, one that accounts for the disk’s radius, width, and asymmetries, with an eccentric ring model that can alter its eccentricity with distance from the star. The best-fitting model pointed to a steep decline in eccentricity with distance, as predicted by dynamical theories of how planets can shape debris disks, but as-yet seen anywhere in the universe.

This negative gradient offers clues about hidden planets, currently unseen by astronomers, orbiting Fomalhaut. The new model suggests a massive planet orbiting inside of Fomalhaut’s disk may have sculpted its eccentricity profile early in the extrasolar system’s history. The unusual shape of the debris disk may have formed in the system’s youth, during the protoplanetary disk phase, and has remained this way for more than 400 million years, thanks to the continued push, and pull of this planet.

In the second paper, led by Graduate Student Jay Chittidi at Johns Hopkins University, the team exhausted the possibility that the ring’s eccentricity is fixed with the distance from the star. “Although the shift in brightness from the pericenter side of the disk, nearest to the star, to the apocenter side, furthest from the star, between the JWST and ALMA data was expected, the precise shifts that we measured in the disk brightness and the ring’s width could not be explained by the old models,” said Jay. “Simply put: we couldn’t find a model with a fixed eccentricity that could explain these peculiar features in Fomalhaut’s disk. Comparing the old and new models, we are now able to better interpret this disk, and reconstruct the history and present state of this dynamic system.”

Researchers hope this new model will be further tested with more ALMA observations, which were recently approved, “And hopefully we’ll find new clues that will help us uncover that planet!” adds Lovell. The team has shared the eccentricity model code developed for this newly published research to enable other astronomers to apply it to similar systems.

Source: National Radio Astronomy Observatory (NRAO)/News

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About NRAO

The National Radio Astronomy Observatory (NRAO) is a facility of the U.S. National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

About ALMA

The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of the European Southern Observatory (ESO), the U.S. National Science Foundation (NSF) and the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Republic of Chile. ALMA is funded by ESO on behalf of its Member States, by NSF in cooperation with the National Research Council of Canada (NRC) and the National Science and Technology Council (NSTC) in Taiwan and by NINS in cooperation with the Academia Sinica (AS) in Taiwan and the Korea Astronomy and Space Science Institute (KASI).

ALMA construction and operations are led by ESO on behalf of its Member States; by the National Radio Astronomy Observatory (NRAO), managed by Associated Universities, Inc. (AUI), on behalf of North America; and by the National Astronomical Observatory of Japan (NAOJ) on behalf of East Asia. The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

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NASA's Chandra Reveals Star's Inner Conflict Before Explosion

X-ray Image of Cassiopeia A
Credit: X-ray: NASA/CXC/Meiji Univ./T. Sato et al.; Image Processing: NASA/CXC/SAO/N. Wolk

JPEG (218 kb) -Large JPEG (3.6 MB) - Tiff (12 MB) - More Images

A Tour of Cassiopeia A - More Videos

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This graphic features data from NASA’s Chandra X-ray Observatory of the Cassiopeia A (Cas A) supernova remnant, a frequent target of the telescope for more than a quarter century. New Chandra data continues to reveal fresh insight into this debris field from an exploded star. In the latest result, astronomers have now used Chandra to learn that the star’s interior violently rearranged itself mere hours before it exploded, as outlined in our press release. This discovery helps scientists better understand how massive stars explode and what happens to their remains afterward.

The main panel of this graphic is Chandra data that has been selected to show the location of different elements in the remains of the explosion: silicon (red), sulfur (yellow), calcium (green) and iron (purple). The blue color reveals the highest-energy X-ray emission detected by Chandra in Cas A, with the blue outer ring highlighting the expanding blast wave from the original explosion hundreds of years ago.

The inset to the upper left zooms in a smaller region of Cas A. This reveals data collected by Chandra that picks up relative amounts of silicon and neon. Areas with large amounts of silicon but smaller amounts of neon are labeled as Silicon-rich and Neon-poor, respectively, and are colored red. Alternatively, areas where Chandra detects the opposite — large amounts of neon but smaller amounts of silicon (Neon-rich and Silicon-poor) — are blue.

Cassiopeia A: A labeled version of the main image showing the relative abundances of silicon and neon in the inset. Credit: X-ray: NASA/CXC/Meiji Univ./T. Sato et al.; Image Processing: NASA/CXC/SAO/N. Wolk

These different regions provide crucial information about the supernova's progenitor, the star that exploded to form Cas A. They give evidence that just a few hours before it exploded, the progenitor's onion-like layers of elements in its interior were disrupted. The researchers think that part of an inner layer with large amounts of silicon traveled outwards and broke into a neighboring layer with lots of neon. This upheaval not only caused material rich in silicon to travel outwards, it also forced material rich in neon to travel inwards. Clear traces of these outward silicon flows and inward neon flows in Cas A are shown in the inset image, corresponding to the Silicon-rich and Neon-poor regions, and the Neon-rich and Silicon-poor regions, respectively.

Cassiopeia A: Schematic Illustration

This illustrated figure shows a cross-section of a massive star similar to the one that created the Cas A supernova remnant. The onion-like layers are dominated by heavier and heavier elements, beginning with hydrogen, and extending to helium, carbon, oxygen, silicon and iron in the center of the star. The cross-section is shown a few hours before the star's explosion as a supernova. Silicon-rich material made in nuclear reactions involving oxygen (in the narrow "O-burning shell"), are buoyant and push outwards in silicon-rich plumes, forcing neon-rich material further out to flow inwards. The motion of these silicon-rich and neon-rich materials disrupt the narrow shell where carbon and neon are undergoing nuclear reactions (the narrow "C-/Ne-burning shell"). Credit: NASA/CXC/Meiji Univ./T. Sato et al.

Because Chandra observes the elements are not smoothly mixed in the remnant now, it suggests there was not complete mixing of the silicon and neon with other elements immediately before or after the explosion.

These results have been published in the latest issue of The Astrophysical Journal and are available online. The authors of the study are Toshiki Sato (Meiji University in Japan), Kai Matsunga (Kyoto University in Japan), Hiroyuki Uchida (Kyoto), Satoru Katsuda (Saitama University in Japan), Koh Takahashi (National Astronomical Observatory of Japan), Hideyuki Umeda (University of Toyko in Japan), Tomoya Takiwaki (NAOJ), Ryo Sawada (University of Toyko), Takashi Yoshida (Kyoto), Ko Nakamura (Fukuoka University in Japan), Yui Kuboike (Meiji), Paul Plucinsky (Center for Astrophysics | Harvard & Smithsonian), and Jack Hughes (Rutgers University).

NASA's Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program. The Smithsonian Astrophysical Observatory's Chandra X-ray Center controls science operations from Cambridge, Massachusetts, and flight operations from Burlington, Massachusetts.

Quick Look: NASA's Chandra Reveals Star's Inner Conflict Before Explosion

Source: NASA’s Chandra X-ray Observatory

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Visual Description:

This release features a composite image of Cassiopeia A, a donut-shaped supernova remnant located about 11,000 light-years from Earth. Included in the image is an inset closeup, which highlights a region with relative abundances of silicon and neon.

Over three hundred years ago, Cassiopeia A, or Cas A, was a star on the brink of self-destruction. In composition it resembled an onion with layers rich in different elements such as hydrogen, helium, carbon, silicon, sulfur, calcium, and neon, wrapped around an iron core. When that iron core grew beyond a certain mass, the star could no longer support its own weight. The outer layers fell into the collapsing core, then rebounded as a supernova. This explosion created the donut-like shape shown in the composite image. The shape is somewhat irregular, with the thinner quadrant of the donut to the upper left of the off-center hole.

In the body of the donut, the remains of the star's elements create a mottled cloud of colors, marbled with red and blue veins. Here, sulfur is represented by yellow, calcium by green, and iron by purple. The red veins are silicon, and the blue veins, which also line the outer edge of the donut-shape, are the highest energy X-rays detected by Chandra and show the explosion's blast wave.

The inset uses a different color code and highlights a colorful, mottled region at the thinner, upper left quadrant of Cas A. Here, rich pockets of silicon and neon are identified in the red and blue veins, respectively. New evidence from Chandra indicates that in the hours before the star's collapse, part of a silicon-rich layer traveled outwards, and broke into a neighboring neon-rich layer. This violent breakdown of layers created strong turbulent flows and may have promoted the development of the supernova's blast wave, facilitating the star's explosion. Additionally, upheaval in the interior of the star may have produced a lopsided explosion, resulting in the irregular shape, with an off-center hole (and a thinner bite of donut!) at our upper left.

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Fast Facts for Cassiopeia A:

Scale: Image is about 12.2 arcmin (39 light-years) across.
Category: Supernovas & Supernova Remnants
Coordinates (J2000): RA 23h 23m 26.7s | Dec +58° 49´ 03.00"
Constellation: Cassiopeia
Observation Dates: Nine observations in 2004: Feb 8, Apr 14, 18, 20, 22, 25 28, May 01, 05
Observation Time: 278 hours (11 days 14 hours)
Obs. ID: 4634-4639, 5196, 5319-5320
Instrument: ACIS
Also Known As: Cas A
References: Sato, T. et al, 2025, Accepted; arXiv:2507.07563.
Color Code: X-ray: red, green, blue; Inset: red, white, blue
Distance Estimate: About 11,000 light-years

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All Alone With No AGN to Call Home? New Results for Little Red Dots

JWST images of six very distant galaxies dubbed "little red dots."
Credit: NASA, ESA, CSA, STScI, Dale Kocevski (Colby College)

Among the discoveries JWST has made since its 2021 launch, “little red dots” are one of the most perplexing. Named for their compact size and red color, the origins of these distant galaxies remain unknown. A recent article explores some little red dots’ spectral energy distributions and local environments to better understand what may be lighting up these tiny torches.

Little Red Dot Dilemma

Along with their size and color, little red dots exhibit “V”-shaped spectral energy distributions (how they emit light across wavelengths), broad hydrogen emission lines, and no observed X-ray emission. These properties land them in an untapped parameter space with some similarities to both active galactic nuclei (AGNs) and stellar populations. Some previous investigations have suggested that little red dots contain AGNs, reddened by a dusty accretion disk scattering or blocking AGN light. Other studies have found that models for stellar populations can also fit certain little red dot spectra well.

Adding to the ambiguity, observations and theory predict AGNs to show broad spectral lines, which are present in little red dots — but if little red dots are AGNs, this implies a much higher density of AGNs in the early universe than previously predicted by ground-based surveys. Furthermore, AGNs are expected to emit in the X-ray and show photometric variability, but neither property has been detected definitively thus far for a little red dot. With a clear dilemma arising for the origins of little red dots, astronomers are still prodding at these curious sources.

Comparison of AGN versus non-AGN fits using the Bayesian information criterion (BIC). Positive values of ΔBIC favor a non-AGN fit, and ~70% of little red dots have positive ΔBIC. Credit: Carranza-Escudero et al 2025

AGN or Not?

Leveraging the wealth of data available from recent JWST surveys, María Carranza-Escudero (University of Manchester) and collaborators built a sample of 124 little red dots spanning redshifts of z ~ 3–10. The authors used both AGN and non-AGN models to fit the spectral energy distribution for each galaxy.

Using a robust statistical analysis, the authors found that AGN models tend to “overfit” the data — with more free parameters, an AGN model can be tweaked in a way that may not actually be physical (e.g., fitting for extremely high dust extinction that would not be possible). Instead, models without AGN components appear to be more appropriate for about 70% of the little red dots in their sample, suggesting that these peculiar objects may have a significant star-forming component powering their emission.

Histograms for two redshift windows showing that little red dots (red) tend to be found in less dense environments than other galaxies (blue) in the same redshift window. Credit: Carranza-Escudero et al 2025

Lonely Neighborhoods

In addition to characterizing little red dots’ emission, the authors analyzed the local environments to compare to other galaxies at similar redshifts. From their analysis, they found that little red dots tend to be found in sparser environments, generally isolated from other galaxies. One explanation for this could be that little red dots in higher-density environments evolve past this peculiar stage faster, which is supported by observations of high-density environments accelerating the evolution of other galaxy types at similar redshifts. However, further investigation is required to better understand the connection between the local environment and little red dot properties.

More little red dots are yet to be discovered, and continued analysis of their emission and environments will uncover more intriguing characteristics. For now, it seems as though little red dots are still a mystery.

By Lexi Gault

Citation

“Lonely Little Red Dots: Challenges to the Active Galactic Nucleus Nature of Little Red Dots through Their Clustering and Spectral Energy Distributions,” María Carranza-Escudero et al 2025 ApJL 989 L50. doi:10.3847/2041-8213/adf73d

Source: American Astronomical Society/AAS-Nova

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QSO MUSEUM: A large atlas of cosmic structures surrounding high-redshift quasars

Figure 1. Nine of the targeted quasars (white circles) and the uncovered cosmic structures as seen in Lyman-alpha emission (blue-green). Each cut-out image is roughly 1 million light years in size. Credit: MPA/Jay Gonzalez Lobos, Fabrizio Arrigoni Battaia

Figure 2: Average surface brightness (top panel) and velocity dispersion (bottom panel) of the Lyman-alpha emission as a function of distance from each of the 120 targeted quasars. The curves are colour-coded according to the luminosity of each quasar. Credit: MPA/Jay Gonzalez Lobos

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Quasars are active supermassive black holes located at the centres of massive galaxies that emit energy levels that far exceed the binding energy of their host galaxies. This substantial amount of energy has the potential to impact the gas within and around the galaxies, thereby influencing their evolution. While the importance of this process is acknowledged, its details are still the subject of significant debate. An international team of researchers led by MPA scientists has now obtained observations of the most extensive sample of hydrogen structures surrounding quasars in the early universe to better understand this feedback process. The data reveal how the gas responds to the energy released by the supermassive black holes over distances of several hundred thousand light years, providing a new way to study the impact of quasars on galaxy evolution.

Quasar feedback plays a key role in shaping the evolution of the most massive galaxies in the universe. As the supermassive black hole at the centre of a galaxy accretes matter, it powers a quasar — a bright, energetic outburst that can blow powerful winds and emit radiation into the surrounding galaxy. This energy can either heat up or sweep away the gas that would otherwise form new stars, thereby effectively shutting down star formation. This explains why giant galaxies stop growing and become filled with older stars. However, in principle, a quasar is not only able to affect its host galaxy's interstellar medium (its local fuel reservoir), but also the surrounding intergalactic gas. This means that a quasar could have an impact also on the fresh fuel for future star formation in the galaxy, thereby accelerating the galaxy quenching. Despite these ideas have been extensively discussed, the details of this feedback process still need to be fully understood.

Since the 1980s, it has been proposed that the impact of quasar energy on the surrounding gas could be assessed by targeting one of the most important lines of the hydrogen atom: the Lyman-alpha line. In a hydrogen atom, the electron can occupy different energy levels, like steps on a ladder. This specific ultraviolet line is emitted when an electron drops from the second energy level to the first. Since hydrogen is the most abundant element in the universe, this transition is ubiquitous and results in such bright emission that it can be seen at distances of billions of light years, enabling us to study galaxies and their surrounding gas in the early universe. Novel wide-field spectrographs, in particular, have opened a new window on the Lyman-alpha emission surrounding quasars. They allow the detection of emitting gas at distances of several hundred thousand light years from their host galaxies with short exposure times (about one hour; see, for example, Highlights from November 2019, May 2022 and January 2025).

Thanks to this new instrumentation — specifically the integral-field spectrograph MUSE on the Very Large Telescope — an international team led by MPA scientists has surveyed the largest sample of quasars to date in order to study their surrounding Lyman-alpha emission. The observations revealed intricate structures enveloping these quasars during cosmic noon, an epoch corresponding to approximately 11.5 billion years ago (examples are shown in Figure 1). Importantly, the 120 targeted quasars cover two orders of magnitude in luminosity, enabling the team to explore the effects of different energy inputs.

The scientists discovered that the surface brightness of the Lyman-alpha emission — how bright the emission appears per unit angular area — depends on quasar luminosity. Brighter quasars are associated with brighter extended emission (see Figure 2, top panel). Similarly, brighter quasars are associated with more turbulent gas reservoirs within about 30 kpc (approximately 100,000 light years; see Figure 2, bottom panel). Both these trends are evidence of the impact of quasar feedback (radiation and winds) on their surroundings. The team is now quantifying these trends in detail. For example, they have found that the velocity dispersion on inner scales varies as a function of quasar luminosity, following a well-defined power law. These findings could be used to test quasar feedback models and how they couple with the gas. Future work will focus on targeting additional line emissions besides Lyman-alpha in order to further constrain the impact of quasars on the gas on such large scales, as well as the physical properties of the emitting gas (e.g. MPA Highlights July 2025).

 Source: Max Planck Institute for Astrophysics/Reasearch Highlghts

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Authors:

Jay González Lobos, Jay
PhD student
Tel: 2030
valegl@mpa-garching.mpg.de

Fabrizio Arrigoni Battaia
Scientific Staff
Tel: 2288
arrigoni@mpa-garching.mpg.de

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Original publication

Jay González Lobos, Fabrizio Arrigoni Battaia, Aura Obreja, Guinevere Kauffmann, Emanuele Paolo Farina, Tiago Costa

QSO MUSEUM III: the circumgalactic medium in Lyα emission around 120 z\sim3 quasars covering the SDSS parameter space. Witnessing the instantaneous AGN feedback on halo scales

Submitted to A&A

Source

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