Friday, January 23, 2026

NASA Webb Finds Young Sun-Like Star Forging, Spewing Common Crystals

NASA’s James Webb Space Telescope’s 2024 NIRCam image shows protostar EC 53 circled. Researchers using new data from Webb’s MIRI proved that crystalline silicates form in the hottest part of the disk of gas and dust surrounding the star — and may be shot to the system’s edges. Credit Image: NASA, ESA, CSA, STScI, Klaus Pontoppidan (NASA-JPL), Joel Green (STScI); Image Processing: Alyssa Pagan (STScI)

This illustration represents half the disk of gas and dust surrounding the protostar EC 53. Stellar outbursts periodically form crystalline silicates, which are launched up and out to the edges of the system, where comets and other icy rocky bodies may eventually form. Credit Illustration: NASA, ESA, CSA, Elizabeth Wheatley (STScI)

This image of protostar EC 53 in the Serpens Nebula, captured by the James Webb Space Telescope’s Near Infrared Camera (NIRCam), shows compass arrows, scale bar, and color key for reference. Credit Image: NASA, ESA, CSA, STScI, Klaus Pontoppidan (NASA-JPL), Joel Green (STScI); Image Processing: Alyssa Pagan (STScI)



Astronomers have long sought evidence to explain why comets at the outskirts of our own solar system contain crystalline silicates, since crystals require intense heat to form and these “dirty snowballs” spend most of their time in the ultracold Kuiper Belt and Oort Cloud. Now, looking outside our solar system, NASA’s James Webb Space Telescope has returned the first conclusive evidence that links how those conditions are possible. The telescope clearly showed for the first time that the hot, inner part of the disk of gas and dust surrounding a very young, actively forming star is where crystalline silicates are forged. Webb also revealed a strong outflow that is capable of carrying the crystals to the outer edges of this disk. Compared to our own fully formed, mostly dust-cleared solar system, the crystals would be forming approximately between the Sun and Earth.

Webb’s sensitive mid-infrared observations of the protostar, cataloged EC 53, also show that the powerful winds from the star’s disk are likely catapulting these crystals into distant locales, like the incredibly cold edge of its protoplanetary disk where comets may eventually form.

“EC 53’s layered outflows may lift up these newly formed crystalline silicates and transfer them outward, like they’re on a cosmic highway,” said Jeong-Eun Lee, the lead author of a new paper in Nature and a professor at Seoul National University in South Korea. “Webb not only showed us exactly which types of silicates are in the dust near the star, but also where they are both before and during a burst.”

The team used Webb’s MIRI (Mid-Infrared Instrument) to collect two sets of highly detailed spectra to identify specific elements and molecules, and determine their structures. Next, they precisely mapped where everything is, both when EC 53 is “quiet” (but still gradually “nibbling” at its disk) and when it’s more active (what’s known as an outburst phase).

This star, which has been studied by this team and others for decades, is highly predictable. (Other young stars have erratic outbursts, or their outbursts last for hundreds of years.) About every 18 months, EC 53 begins a 100-day, bombastic burst phase, kicking up the pace and absolutely devouring nearby gas and dust, while ejecting some of its intake as powerful jets and outflows. These expulsions may fling some of the newly formed crystals into the outskirts of the star’s protoplanetary disk.

“Even as a scientist, it is amazing to me that we can find specific silicates in space, including forsterite and enstatite near EC 53,” said Doug Johnstone, a co-author and a principal research officer at the National Research Council of Canada. “These are common minerals on Earth. The main ingredient of our planet is silicate.” For decades, research has also identified crystalline silicates not only on comets in our solar system, but also in distant protoplanetary disks around other, slightly older stars — but couldn’t pinpoint how they got there. With Webb’s new data, researchers now better understand how these conditions might be possible.

“It’s incredibly impressive that Webb can not only show us so much, but also where everything is,” said Joel Green, a co-author and an instrument scientist at the Space Telescope Science Institute in Baltimore, Maryland. “Our research team mapped how the crystals move throughout the system. We’ve effectively shown how the star creates and distributes these superfine particles, which are each significantly smaller than a grain of sand.”

Webb’s MIRI data also clearly shows the star’s narrow, high-velocity jets of hot gas near its poles, and the slightly cooler and slower outflows that stem from the innermost and hottest area of the disk that feeds the star. The image above, which was taken by another Webb instrument, NIRCam (Near-Infrared Camera), shows one set of winds and scattered light from EC 53’s disk as a white semi-circle angled toward the right. Its winds also flow in the opposite direction, roughly behind the star, but in near-infrared light, this region appears dark. Its jets are too tiny to pick out.

Look ahead

EC 53 is still “wrapped” in dust and may be for another 100,000 years. Over millions of years, while a young star’s disk is heavily populated with teeny grains of dust and pebbles, an untold number of collisions will occur that may slowly build up a range of larger rocks, eventually leading to the formation of terrestrial and gas giant planets. As the disk settles, both the star itself and any rocky planets will finish forming, the dust will largely clear (no longer obscuring the view), and a Sun-like star will remain at the center of a cleared planetary system, with crystalline silicates “littered” throughout.

EC 53 is part of the Serpens Nebula, which lies 1,300 light-years from Earth and is brimming with actively forming stars.

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).




Related Links

Read more: Webb’s Star Formation Discoveries

Explore more: Image Tour: Herbig-Haro 46/47

Read more: First-of-Its-Kind Detection Made in Striking New Webb Image

Read more: Infographic: Recipe for planet formation

Explore more: Star formation in the Eagle Nebula

Video: Exploring Star and Planet Formation

More Webb News

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Webb Science Themes

Webb Mission Page



Location: NASA Goddard Space Flight Center

Contact Media:

Laura Betz
NASA’s Goddard Space Flight Center
Greenbelt, Maryland

laura.e.betz@nasa.gov

Claire Blome
Space Telescope Science Institute
Baltimore, Maryland

Christine Pulliam
Space Telescope Science Institute
Baltimore, Maryland



Intricacies of Helix Nebula Revealed With NASA’s Webb

This new image of a portion of the Helix Nebula from NASA’s James Webb Space Telescope highlights comet-like knots, fierce stellar winds, and layers of gas shed off by a dying star interacting with its surrounding environment. Credit Image: NASA, ESA, CSA, STScI; Image Processing: Alyssa Pagan (STScI)

This image of the Helix Nebula from the ground-based Visible and Infrared Telescope for Astronomy (left) shows the full view of the planetary nebula, with a box highlighting Webb’s field of view (right). Credit Image: ESO, VISTA, NASA, ESA, CSA, STScI, J. Emerson (ESO); Acknowledgment: CASU

This image of the Helix Nebula, captured by the NIRCam (Near-Infrared Camera) instrument on Webb, includes compass arrows, scale bar, and color key for reference. Credit Image: NASA, ESA, CSA, STScI; Image Processing: Alyssa Pagan (STScI)

This video compares images of the Helix Nebula from three NASA observatories: Hubble’s image in visible light, Spitzer’s infrared view, and Webb’s high-resolution near-infrared look. Credit Video: NASA, ESA, CSA, STScI, Alyssa Pagan (STScI); Acknowledgment: NASA/JPL-Caltech, ESO, VISTA, CASU, Joseph Hora (CfA), J. Emerson (ESO). (Video)



NASA’s James Webb Space Telescope has zoomed into the Helix Nebula to give an up-close view of the possible eventual fate of our own Sun and planetary system. In Webb’s high-resolution look, the structure of the gas being shed off by a dying star comes into full focus. The image reveals how stars recycle their material back into the cosmos, seeding future generations of stars and planets, as NASA explores the secrets of the universe and our place in it.

In the image from Webb’s NIRCam (Near-Infrared Camera), pillars that look like comets with extended tails trace the circumference of the inner region of an expanding shell of gas. Here, blistering winds of fast-moving hot gas from the dying star are crashing into slower moving colder shells of dust and gas that were shed earlier in its life, sculpting the nebula’s remarkable structure.

The iconic Helix Nebula has been imaged by many ground- and space-based observatories over the nearly two centuries since it was discovered. Webb’s near-infrared view of the target brings these knots to the forefront compared to the ethereal image from NASA’s Hubble Space Telescope, while its increased resolution sharpens focus from NASA’s retired Spitzer Space Telescope’s snapshot. Additionally, the new near-infrared look shows the stark transition between the hottest gas to the coolest gas as the shell expands out from the central white dwarf.

A blazing white dwarf, the leftover core of the dying star, lies right at the heart of the nebula, out of the frame of the Webb image. Its intense radiation lights up the surrounding gas, creating a rainbow of features: hot ionized gas closest to the white dwarf, cooler molecular hydrogen farther out, and protective pockets where more complex molecules can begin to form within dust clouds. This interaction is vital, as it’s the raw material from which new planets may one day form in other star systems.

In Webb’s image of the Helix Nebula, color represents the temperature and chemistry. A touch of a blue hue marks the hottest gas in this field, energized by intense ultraviolet light from the white dwarf. Farther out, the gas cools into the yellow regions where hydrogen atoms join into molecules. At the outer edges, the reddish tones trace the coolest material, where gas begins to thin and dust can take shape. Together, the colors show the star’s final breath transforming into the raw ingredients for new worlds, adding to the wealth of knowledge gained from Webb about the origin of planets.

Spitzer’s studies of the Helix Nebula hinted at the formation of more complex molecules, but Webb’s resolution shows how they form in shielded zones of the scene. In the Webb image, look for dark pockets of space amid the glowing orange and red.

The Helix Nebula is located 650 light-years away from Earth in the constellation Aquarius. It remains a favorite among stargazers and professional astronomers alike due to its relative proximity to Earth, and its similar appearance to the “Eye of Sauron.”

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).




Related Links

Read more: NASA’s Webb Traces Details of Complex Planetary Nebula

Explore more: ViewSpace Star Death: Helix Nebula

Explore more: ViewSpace Celestial Tour: Planetary Nebulae—Sculptures in the Sky

Explore more:Stellar Evolution Flipbook Activity Guide

More Webb News

More Webb Images

Webb Science Themes

Webb Mission Page



Location: NASA Goddard Space Flight Center

Contact Media:

Laura Betz
NASA’s Goddard Space Flight Center
Greenbelt, Maryland

laura.e.betz@nasa.gov

Hannah Braun
Space Telescope Science Institute
Baltimore, Maryland


Christine Pulliam
Space Telescope Science Institute
Baltimore, Maryland



Thursday, January 22, 2026

ALMA Reveals Teenage Years of New Worlds

This ARKS gallery of faint debris disks reveals details about their shape: belts with multiple rings, wide smooth halos, sharp edges, and unexpected arcs and clumps, which hint at the presence of planets shaping these disks; and chemical make-up: the amber colors highlight the location and abundance of the dust in the 24 disks surveyed, while the blue their carbon monoxide gas location and abundance in the six gas-rich disks. Credit: Sebastian Marino, Sorcha Mac Manamon, and the ARKS collaboration. Hi-Res File



New astronomical survey captures previously unknown growing pains in the lives of planets

Astronomers have, for the first time, captured a detailed snapshot of planetary systems in an era long shrouded in mystery. The ALMA survey to Resolve exoKuiper belt Substructures (ARKS), using the Atacama Large Millimeter/submillimeter Array (ALMA), has produced the sharpest images ever of 24 debris disks, the dusty belts left after planets finish forming. These disks are the cosmic equivalent of the teenage years for planetary systems—somewhat more mature than newborn, planet-forming disks, but not yet settled into adulthood.

A Missing Link in Planetary Family Albums

“We’ve often seen the ‘baby pictures’ of planets forming, but until now, the ‘teenage years’ have been a missing link,” says Meredith Hughes, an Associate Professor of Astronomy at Wesleyan University and co-PI of this study.

Our own Solar System’s counterpart to this phase is the Kuiper Belt, a ring of icy debris beyond Neptune that preserves a record of massive collisions and planetary migrations from billions of years ago. By studying 24 exoplanetary debris belts, the ARKS team has opened a window into what our Solar System went through as the Moon was forming and as planets jostled for their final places, and sometimes trading orbits!

Teenage Disks: Hard to “Photograph,” Impossible to Ignore

Debris disks are faint, hundreds or even thousands of times dimmer than the bright, gas-rich disks where planets are born. The ARKS team overcame these challenges and produced images of these disks in unprecedented detail. Like teenagers dodging the camera, these faint disks have managed to hide from astronomers for years. But, thanks to ALMA, astronomers can now see their complex structures: belts with multiple rings, wide smooth halos, sharp edges, and even unexpected arcs and clumps.

“We’re seeing real diversity—not just simple rings, but multi-ringed belts, halos, and strong asymmetries, revealing a dynamic and violent chapter in planetary histories,” adds Sebastián Marino, program lead for ARKS, and an Associate Professor at the University of Exeter.

Highlights and Firsts from ARKS
  • A New Benchmark: ARKS is the largest, highest-resolution survey of debris disks, akin to a ‘DSHARP-for-debris-disks’, setting a new gold standard.

  • A Dynamic, Violent Youth: About one-third of observed disks show clear substructures (multiple rings or distinct gaps) suggesting legacy features left from earlier, planet-building stages or sculpted by planets over much longer timescales.

  • Unexpected Diversity: While some disks inherit intricate structures from their earlier years, others mellow out and spread into broad belts, similar to how we expect the Solar System to have developed.

  • Clues to Planetary ‘Stirring’: Many disks show evidence for zones of calm and chaos, with vertically “puffed-up” regions, akin to our Solar System’s own mix of serene classical Kuiper Belt objects and those scattered by Neptune’s long-ago migration.

  • Surprising Gas Survivors: Several disks retain gas much longer than expected. In some systems, lingering gas may shape the chemistry of growing planets, or even push dust into wide halos.

  • Asymmetries and Arcs: Many disks are lopsided, with bright arcs or eccentric shapes, hinting at gravitational shoves from unseen planets, leftover birth scars from planetary migration, or interactions between the gas and dust.

  • Public Data Release: All ARKS observations and processed data are being made freely available to astronomers worldwide, enabling further discoveries.

Implications: Your Solar System Was Once a Wild Ride

The ARKS results show this teenage phase is a time of transition and turmoil. “These disks record a period when planetary orbits were being scrambled and huge impacts, like the one that forged Earth’s Moon, were shaping young solar systems,” says Luca Matrà, a co-PI on the survey, and Associate Professor at Trinity College Dublin.

By looking at dozens of disks around stars of different ages and types, ARKS helped decode whether chaotic features are inherited, sculpted by planets, or arise from other cosmic forces. Answering these questions could reveal whether our Solar System’s history was unique, or the norm.

Looking Ahead: Hunting for Planetary Architects

The ARKS survey’s findings are a treasure trove for astronomers hunting for young planets and seeking to understand how planet families, like our own, are built and rearranged.

“This project gives us a new lens for interpreting the craters on the Moon, the dynamics of the Kuiper Belt, and the growth of planets big and small. It’s like adding the missing pages to the Solar System’s family album,” adds Hughes.

The ARKS survey is the work of an international team of approximately 60 scientists, led by the University of Exeter, Trinity College Dublin, and Wesleyan University. For more information, visit https://arkslp.org/.




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.



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.



Leadership Team

S. Marino (University of Exeter), A. M. Hughes (Wesleyan University), and L. Matrà (Trinity College Dublin)


Collaboration Members

Y. Han (Caltech), B. Zawadzki (Wesleyan University), S. Mac Manamon (Trinity College Dublin), J. Milli (IPAG), J. B. Lovell (Center for Astrophysics, Harvard & Smithsonian), A. Brennan (Trinity College Dublin), P. Weber (Usach, Núcleo Milenio YEMS), M. R. Jankovic (University of Belgrade), M. C. Wyatt (University of Cambridge), T. Löhne (Friedrich-Schiller-Universität Jena), P. Ábrahám (Konkoly Observatory), M. Bonduelle (IPAG), A. S. Hales (NRAO), M. Booth (UKATC), C. del Burgo (Universidad de La Laguna; Instituto de Astrofísica de Canarias), J. M. Carpenter (ALMA), G. Cataldi (NAOJ), E. Chiang (Berkeley), E. Choquet (LAM), S. Ertel (University of Arizona), A. Fehr (Center for Astrophysics, Harvard & Smithsonian), J. Olofsson (ESO), Th. Henning (MPIA), J. Jennings (Flatiron Institute), G. M. Kennedy (Victoria University), Á. Kóspál (Konkoly Observatory), A. V. Krivov (Friedrich-Schiller-Universität Jena), P. Luppe (Trinity College Dublin), M. A. MacGregor (Johns Hopkins University), E. Mansell (Wesleyan University), J. P. Marshall (ASIAA), B. C. Matthews (University of Victoria), A. Moór (Konkoly Observatory), K. Öberg (Center for Astrophysics, Harvard & Smithsonian), N. Pawellek (University of Vienna), T. D. Pearce (University of Warwick), S. Pérez (Usach, Núcleo Milenio YEMS), A. A. Sefilian (University of Arizona), A. G. Sepulveda (UT Law), D. J. Wilner (Center for Astrophysics, Harvard & Smithsonian), C. Baruteau (IRAP), R. Bendahan-West (University of Exeter), A. Bayo (ESO), R. Booth (University of Leeds), F. Castillo (Usach, Núcleo Milenio YEMS), A. Cheruiyot (Wesleyan University), J. Ehrhardt (ESO), Th. M. Esposito (Berkeley), V. Gupta (University of Exeter), J. Hom (University of Arizona), A. Higuchi (Musashino University), C. Hou (Wesleyan University), J. Kittling (KIPAC), Hiroshi Kobayashi (Nagoya University), J. Lee (Wesleyan University), Y. Mpofu (Wesleyan University), R. Nakatani (UNIMI), A. Nurmohamed (Wesleyan University), M. Pan (Center for Astrophysics, Harvard & Smithsonian), V. Squicciarini (University of Exeter), J. Zander (Friedrich-Schiller-Universität Jena).

Funding Acknowledgement

ARKS would not have been possible without the support of ALMA and its partners—the European Southern Observatory representing its member states, the United States National Science Foundation, and the National Institutes of Natural Sciences of Japan, together with the National Research Council of Canada, the Ministry of Science and Technology of Taiwan and the Academia Sinica Institute of Astronomy and Astrophysics, and the Korea Astronomy and Space Science Institute, in cooperation with the Republic of Chile; the Beatriz Galindo grant program; the Brinson Foundation; the Canadian Advanced Network for Astronomy Research supported by the National Research Council of Canada, the Canadian Space Agency, CANARIE, the Canadian Foundation for Innovation, and the Digital Research Alliance of Canada; the Chilean National Agency for Research and Development including the FONDECYT programme and the Millennium Science Initiative Program; the Consejería de Economía, Conocimiento y Empleo of the Government of the Canary Islands; the European Research Council (grants FEED and E-BEANS, numbers 101162711 and 100117693 ); the French National Planetology Program; the French National Research Agency; the Gates Cambridge Trust; the Heising–Simons Foundation; the Hungarian Ministry of Culture and Innovation through the National Research, Development and Innovation Fund; the Irish Research Council; the Institute of Physics Belgrade; Marie Skłodowska-Curie Actions; the NASA Connecticut Space Grant Consortium; the NASA Exoplanet Research Program; the North American ALMA Science Center; the Opticon–RadioNet Pilot funded by the European Union’s Horizon 2020 research and innovation programme; the Royal Society; the Smithsonian Institution; the Simons Foundation; the Space Telescope Science Institute; the Spanish Ministry of Science, Innovation and Universities and the European Regional Development Fund; the United Kingdom node of the European ALMA Regional Centre; United Kingdom Research and Innovation; the United States National Science Foundation; the University of La Laguna; the Warwick Prize Fellowship; the Ministry of Science, Technological Development and Innovations of the Republic of Serbia; and the National Science and Technology Council of Taiwan.


Wednesday, January 21, 2026

Mysterious iron 'bar' discovered in famous nebula

A composite RGB image of the Ring Nebula (also known as Messier 57 and NGC 6720) constructed from four WEAVE/LIFU emission-line images. The bright outer ring is made up of light emitted by three different ions of oxygen, while the ‘bar’ across the middle is due to light emitted by a plasma of four-times-ionised iron atoms. North is up and East is to the left in the image. Credit: University College London
Licence type: Attribution (CC BY 4.0)

A mysterious bar-shaped cloud of iron has been discovered inside the iconic Ring Nebula by a European team led by astronomers at University College London (UCL) and Cardiff University.

The cloud of iron atoms, described for the first time in Monthly Notices of the Royal Astronomical Society, is in the shape of a bar or strip: it just fits inside the inner layer of the elliptically shaped nebula, familiar from many images including those obtained by the James Webb Space Telescope at infrared wavelengths1.

The bar's length is roughly 500 times that of Pluto’s orbit around the Sun and, according to the team, its mass of iron atoms is comparable to the mass of Mars.

The Ring Nebula, first spotted in 1779 in the northern constellation of Lyra by the French astronomer Charles Messier2, is a colourful shell of gas thrown off by a star as it ends the nuclear fuel-burning phase of its life. Our own Sun will expel its outer layers in a similar way in a few billion years' time.3

The iron cloud was discovered in observations obtained using the Large Integral Field Unit (LIFU) mode of a new instrument, the WHT Enhanced Area Velocity Explorer (WEAVE)4, installed on the Isaac Newton Group’s 4.2-metre William Herschel Telescope5.

The LIFU is a bundle of hundreds of optical fibres. It has enabled the team of astronomers to obtain spectra (where light is separated into its constituent wavelengths) at every point across the entire face of the Ring Nebula, and at all optical wavelengths, for the first time.

Lead author Dr Roger Wesson, based jointly at UCL and Cardiff University, said: "Even though the Ring Nebula has been studied using many different telescopes and instruments, WEAVE has allowed us to observe it in a new way, providing so much more detail than before.

"By obtaining a spectrum continuously across the whole nebula, we can create images of the nebula at any wavelength and determine its chemical composition at any position.

"When we processed the data and scrolled through the images, one thing popped out as clear as anything – this previously unknown 'bar' of ionized iron atoms, in the middle of the familiar and iconic ring."

An illustrative set of 8 individual WEAVE LIFU emission-line images of the Ring Nebula. The colour in each panel tracks the brightness of emission, with brown-red being the most intense, shading through yellow and green to blue for the faintest emission. North is up and east, left. Credit: University College London
Licence type: Attribution (CC BY 4.0)

How the iron bar formed is currently a mystery, the authors say. They will need further, more detailed observations to unravel what is going on. There are two potential scenarios: the iron bar may reveal something new about how the ejection of the nebula by the parent star progressed, or (more intriguingly) the iron might be an arc of plasma resulting from the vaporisation of a rocky planet caught up in the star’s earlier expansion.

Co-author Professor Janet Drew, also based at UCL, said: "We definitely need to know more – particularly whether any other chemical elements co-exist with the newly-detected iron, as this would probably tell us the right class of model to pursue. Right now, we are missing this important information."

The team are working on a follow-up study, and plan to obtain data using WEAVE's LIFU at higher spectral resolution to better understand how the bar might have formed.

WEAVE is carrying out eight surveys over the next five years, targeting everything from nearby white dwarfs to very distant galaxies. The Stellar, Circumstellar and Interstellar Physics strand of the WEAVE survey, led by Professor Drew, is observing many more ionized nebulae across the northern Milky Way.

"It would be very surprising if the iron bar in the Ring is unique," explains Dr. Wesson. "So hopefully, as we observe and analyse more nebulae created in the same way, we will discover more examples of this phenomenon, which will help us to understand where the iron comes from."

Professor Scott Trager, WEAVE Project Scientist based at the University of Groningen, added: "The discovery of this fascinating, previously unknown structure in a night-sky jewel, beloved by sky watchers across the Northern Hemisphere, demonstrates the amazing capabilities of WEAVE.

"We look forward to many more discoveries from this new instrument."




Media contacts:

Sam Tonkin
Royal Astronomical Society
Mob: +44 (0)7802 877 700

press@ras.ac.uk

Mark Greaves
University College London
Mob: +44 (0)7990 675 947

m.greaves@ucl.ac.uk

Science contacts:

Dr Roger Wesson
University College London/Cardiff University

rw@nebulousresearch.org

Professor Janet Drew
University College London

j.drew@ucl.ac.uk



Images & captions

Figure 1: A composite RGB image of the Ring Nebula (also known as Messier 57 and NGC 6720) constructed from four WEAVE/LIFU emission-line images. The bright outer ring is made up of light emitted by three different ions of oxygen, while the ‘bar’ across the middle is due to light emitted by a plasma of four-times-ionised iron atoms. North is up and East is to the left in the image.

RGB key:- Red: the bar-shaped emission from four-times-ionized iron atoms in the [Fe V] spectral line at a wavelength of 4227 Angstrom (422.7 nm). Also shown in red, in the main ring, is emission in the [O I] 6300 Angstrom auroral line produced by neutral oxygen atoms. Green: emission in the [O II] 3727 Angstrom line pair emitted by singly-ionized oxygen atoms. Blue: emission in the [O III] 4959 Angstrom line of doubly-ionized oxygen atoms.

The angular dimensions of the image are 120 x 110 arcseconds on the sky (E-W x N-S), corresponding to physical dimensions of 95,000 x 87,000 Astronomical Units (AU) for the 787 parsec distance to the Ring Nebula. An Astronomical Unit is the mean distance from the Sun to the Earth.Credit: University College London


Figure 2: An illustrative set of 8 individual WEAVE LIFU emission-line images of the Ring Nebula. The colour in each panel tracks the brightness of emission, with brown-red being the most intense, shading through yellow and green to blue for the faintest emission. North is up and east, left.

The 4 emission line images that are combined in Figure 1 are shown separately in the top row. Left to right, the emission lines are: the [Fe V] 4227 Angstrom (422.7 nm) line due to four-times-ionized iron atoms; the [O I] 6300 Angstrom auroral line due to neutral oxygen atoms; the [O II] 3727 Angstrom line pair due to singly-ionized oxygen atoms; the [O III] 4959 Angstrom line due to twice-ionized oxygen atoms.

Bottom row, from left to right: emission in the 4861-Angstrom line that is produced as ionized hydrogen atoms recombine in the nebula; emission in the [N II] 6548 Angstrom line of singly-ionized nitrogen; emission in the C II 4267 Angstrom line resulting from the recombination of twice-ionized carbon atoms; emission in the [Ar V] 6435 Angstrom line by four-times-ionized argon.

Notice the very different appearance of the emission from four times ionized iron atoms (top left) compared to the emission from four-times-ionized argon atoms (bottom right) – usually, these ions of argon and iron arise in the same volume, as they require the same physical conditions.

The angular dimensions of each of the 8 frames are 120 x 110 arcseconds on the sky (E-W x N-S), corresponding to physical dimensions of 95,000 x 87,000 Astronomical Units (AU) at the 787 parsec distance of the Ring Nebula. An Astronomical Unit is the mean distance from the Sun to the Earth. Credit: University College London




Further information

The paper ‘WEAVE imaging spectroscopy of NGC 6720: an iron bar in the Ring’ by R. Wesson et al. has been published in Monthly Notices of the Royal Astronomical Society. DOI: 10.1093/mnras/staf2139.

See e.g. https://www.ucl.ac.uk/news/2023/aug/second-james-webb-image-ring-nebula-hints-dying-stars-companion

https://www.cardiff.ac.uk/news/view/2739414-astronomers-spy-structures-that-no-previous-telescope-could-detect-in-new-images-of-dying-star

2 The Ring Nebula is also known as M 57 – the 57th listing in Messier’s catalogue of ‘Nebulae and Star Clusters’. John L E Dreyer also included it in his New General Catalogue, first published in 1888 by the Royal Astronomical Society, where it appears as NGC 6720.

3 Once a star like the Sun runs out of hydrogen fuel, it expands to become an extreme red giant and sheds its outer layers, which then coast out to form a glowing shell. A shell created in this way is known in astronomy as a planetary nebula. The leftover stellar core becomes a white dwarf, which, though no longer burning any fuel, continues to shine as it slowly cools over billions of years. The Ring Nebula is a planetary nebula located 2,600 light years (or 787 parsec) away, that is thought to have formed about 4,000 years ago. Planetary nebula ejection returns matter forged in a star to interstellar space and is the source of much of the Universe’s carbon and nitrogen – key building blocks of life on Earth. Stars more than about eight times the mass of the Sun age differently, ending life abruptly in a powerful explosion called a supernova as they collapse to form a black hole or neutron star.

4 Funding for the WEAVE facility has been provided by UKRI STFC, the University of Oxford, NOVA, NWO, Instituto de Astrofísica de Canarias (IAC), the Isaac Newton Group partners (STFC, NWO, and Spain, led by the IAC), INAF, CNRS-INSU, the Observatoire de Paris, Région Île-de-France, CONACYT through INAOE, the Ministry of Education, Science and Sports of the Republic of Lithuania, Konkoly Observatory (CSFK), Max-Planck-Institut für Astronomie (MPIA Heidelberg), Lund University, the Leibniz Institute for Astrophysics Potsdam (AIP), the Swedish Research Council, the European Commission, and the University of Pennsylvania. The WEAVE Survey Consortium consists of the ING, its three partners, represented by UKRI STFC, NWO, and the IAC, NOVA, INAF, GEPI, INAOE, Vilnius University, FTMC – Center for Physical Sciences and Technology (Vilnius), and individual WEAVE Participants. The WEAVE website can be found at https://weave-project.atlassian.net/wiki/display/WEAVE and the full list of granting agencies and grants supporting WEAVE can be found at https://weave-project.atlassian.net/wiki/display/WEAVE/WEAVE+Acknowledgements.

5The William Herschel Telescope is the leading telescope of the Isaac Newton Group (ING), which in turn is part of the Roque de los Muchachos Observatory on La Palma, in the Canary Islands. The ING is jointly operated by the United Kingdom (STFC-UKRI), the Netherlands (NWO) and Spain (IAC, funded by the Spanish Ministry of Science, Innovation and Universities).



Notes for editors

About the Royal Astronomical Society

The Royal Astronomical Society (RAS), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science.

The RAS organises scientific meetings, publishes international research and review journals, recognises outstanding achievements by the award of medals and prizes, maintains an extensive library, supports education through grants and outreach activities and represents UK astronomy nationally and internationally. Its more than 4,000 members (Fellows), a third based overseas, include scientific researchers in universities, observatories and laboratories as well as historians of astronomy and others.

The RAS accepts papers for its journals based on the principle of peer review, in which fellow experts on the editorial boards accept the paper as worth considering. The Society issues press releases based on a similar principle, but the organisations and scientists concerned have overall responsibility for their content.



Keep up with the RAS on Instagram, Bluesky, LinkedIn, Facebook and YouTube.

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Submitted by Sam Tonkin on Fri, 16/01/2026 - 00:01


Tuesday, January 20, 2026

ALMA and the NSF VLA Use a Cosmic Lens to Reveal a Hyperactive Cradle of a Future Galaxy Cluster

The galaxy cluster lens J0846 in optical light (bottom right), the ALMA view of dust-enshrouded, star-forming galaxies strongly lensed into bright arcs (top right), and a composite view (left) revealing at least 11 dusty galaxies in a compact protocluster core more than 11 billion light-years away, magnified by the foreground cluster’s gravity. Credit: NSF/AUI/NSF NRAO/B. Saxton; NSF/NOIRLab



ALMA observations, together with NSF VLA, uncover the first strongly lensed protocluster core, revealing an intense burst of galaxy growth in the early universe

Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA), together with the U.S. National Science Foundation Very Large Array (NSF VLA), have uncovered a rare, extraordinarily active region of the early universe where a future galaxy cluster is rapidly forming. By exploiting a powerful natural phenomenon known as gravitational lensing, ALMA revealed a compact, dust-enshrouded swarm of young galaxies forming stars at an exceptional rate more than 11 billion years ago.

The discovery marks the first strongly lensed protocluster core ever identified, providing an unprecedented, magnified view of one of the universe’s earliest large-scale structures in formation. Complementary observations with the NSF VLA helped characterize both the distant galaxies and the massive foreground cluster responsible for the lensing effect.

Galaxy clusters are the largest gravitationally bound structures in the universe. Their ancestors, known as protoclusters, are regions where galaxies are still assembling, rapidly converting gas into stars and growing in mass. Studying these systems allows astronomers to trace how today’s massive clusters emerged from much smaller, denser environments in the early cosmos.

ALMA’s high-resolution observations revealed that what initially appeared as a single bright source in all-sky survey data is actually a tightly packed group of at least 11 dusty, star-forming galaxies. These galaxies are confined to a region only a few hundred thousand light-years across — remarkably compact on cosmic scales — and are experiencing intense bursts of star formation.

Because these galaxies are heavily shrouded in dust, most of their visible light is absorbed and re-emitted at millimeter and submillimeter wavelengths. ALMA’s sensitivity to this cold dust and molecular gas allowed astronomers to detect the raw material fueling star formation and to measure the dynamics of the system with exceptional clarity.

The protocluster lies behind a massive foreground galaxy cluster whose gravity acts as a cosmic magnifying glass, bending and amplifying the light from the more distant system. This gravitational lensing effect dramatically boosts ALMA and the NSF VLA’s ability to resolve individual galaxies and study their properties in detail, effectively turning the universe itself into a telescope.

ALMA detected carbon monoxide (CO) emission, a key tracer of molecular gas, helping confirm that the galaxies share a common distance and form a physically connected structure. These observations show that the protocluster core contains enormous gas reservoirs capable of sustaining vigorous star formation and driving the rapid buildup of stellar mass.

Complementary observations with the NSF VLA provided radio-frequency data that helped map the foreground cluster and identify radio emission associated with both star formation and energetic processes within the system, strengthening the interpretation of the lensing configuration and the nature of the galaxies involved.

“Galaxy clusters are akin to a sprawling modern metropolis that was built upon an ancient civilization from the past. For example, if an archaeologist digs deeper into the ground, then they uncover an earlier civilization. Similarly, when astronomers observe objects farther away, they can look further back in time. In this way, the study of this distant protocluster gives us a glimpse into how one of the earliest ‘settlements’ of galaxies grew and evolved into the mature structures such as that foreground galaxy cluster that we observe today,” said Nicholas Foo, a graduate student at Arizona State University.

Protoclusters like this one represent the earliest construction phases of galaxy clusters seen in the present-day universe. By combining ALMA’s detailed view of cold gas and dust with complementary radio observations from the NSF VLA, astronomers can investigate how galaxies grow, interact, and evolve in the densest environments of the early cosmos.

This rare alignment of a young protocluster and a massive foreground lens provides an exceptional opportunity to test theories of galaxy and cluster formation. Future ALMA observations will further explore how these compact, dust-rich systems evolve and how their extreme environments shape the galaxies that will eventually populate massive clusters billions of years later.




Additional Information

The results of this research appear as "PASSAGES: The Discovery of a Strongly Lensed Protocluster Core Candidate at Cosmic Noon" in the Astrophysical Journal by N. foo et al.

The original press release was published by the National Radio Astronomy Observatory of the United States, an ALMA partner, on behalf of North America.

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.



Contacts:

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

Jill Malusky
Public Information Officer
NRAO
Phone:
+1 304-456-2236
Email:jmalusky@nrao.edu

Bárbara Ferreira
ESO Media Manager
Garching bei München, Germany
Phone:
+49 89 3200 6670
Email: press@eso.org

Yuichi Matsuda
Education and Public Outreach Officer
NAOJ
Email:
yuichi.matsuda@nao.ac.jp


Monday, January 19, 2026

'Reborn' black hole spotted 'erupting like cosmic volcano'

This LOFAR DR2 image of J1007+3540 superimposed over an optical image by Pan-STARRS shows a compact, bright inner jet, indicating the reawakening of what had been a ‘sleeping’ supermassive black hole at the heart of the gigantic radio galaxy. Credit: LOFAR/Pan-STARRS/S. Kumari et al.
Licence type: Attribution (CC BY 4.0)

One of the most vivid portraits of “reborn” black hole activity – likened to the eruption of a “cosmic volcano” spreading almost one million light-years across space – has been captured in a gigantic radio galaxy.

The dramatic scene was uncovered when astronomers spotted the supermassive black hole at the heart of J1007+3540 restarting its jet emission after nearly 100 million years of silence.

Radio images revealed the galaxy locked in a messy, chaotic struggle between the black hole's newly ignited jets and the crushing pressure of the massive galaxy cluster in which it resides.

They have been published today in Monthly Notices of the Royal Astronomical Society after being obtained using highly sensitive radio interferometers – the Low Frequency Array (LOFAR) in the Netherlands and India’s upgraded Giant Metrewave Radio Telescope (uGMRT).

Most galaxies host a supermassive black hole, but only a few produce vast jets of radio-emitting magnetised plasma. J1007+3540 is unique, the international team of researchers behind the new study say, because it shows clear evidence of multiple eruptions – proof that its central engine has turned on, shut down, and restarted after long periods of quiet.

The radio images show a compact, bright inner jet, which lead researcher Shobha Kumari, of Midnapore City College in India, said was the unmistakable sign of the black hole’s recent awakening. Just outside it lies a cocoon of older, faded plasma – leftover debris from the black hole’s past eruptions, distorted and squeezed by the hostile environment around it.

“It’s like watching a cosmic volcano erupt again after ages of calm – except this one is big enough to carve out structures stretching nearly a million light-years across space”, Kumari added.

“This dramatic layering of young jets inside older, exhausted lobes is the signature of an episodic AGN – a galaxy whose central engine keeps turning on and off over cosmic timescales.”

The research was carried out by Kumari and co-authors Dr Sabyasachi Pal, of Midnapore City College, Dr Surajit Paul, associate professor at the Manipal Centre for Natural Sciences in India, and Dr Marek Jamrozy, of Jagiellonian University in Poland.

“J1007+3540 is one of the clearest and most spectacular examples of episodic AGN with jet-cluster interaction, where the surrounding hot gas bends, compresses, and distorts the jets,” Dr Pal said.

The same images with labels showing the compressed northern lobe, curved backflow signature of plasma and the inner jet of the black hole. Credit: LOFAR/Pan-STARRS/S. Kumari et al.
Licence type: Attribution (CC BY 4.0)

J1007+3540 lives inside a massive galaxy cluster filled with extremely hot gas. This environment creates enormous external pressure – far higher than what most radio galaxies experience. As the revived jets push outward, they are bent, squeezed, and distorted by the interaction with the dense medium.

The LOFAR image reveals that the northern lobe is compressed and dramatically distorted, the authors say, showing a curved backflow signature of plasma that seems to be shoved sideways by the surrounding gas.

The uGMRT image also shows that this compressed region has an ultra-steep radio spectrum, meaning the particles there are extremely old and have lost much of their energy – another sign of the cluster’s harsh influence.

The long, faint tail of diffuse emission stretching to the southwest tells an equally dramatic story, the researchers say. It shows that magnetised plasma is being dragged in a large extension through the cluster environment, leaving behind a wispy trail millions of years old. This, they add, suggests the galaxy is not just producing jets, it is also being shaped and sculpted by the powerful environment around it.

Systems such as J1007+3540 are extremely valuable to astronomers. They reveal how black holes turn on and off, how jets evolve over millions of years, and how cluster environments can reshape the entire morphological structure of a radio galaxy.

The combination of restarted activity, giant scale, and strong environmental pressure makes J1007+3540 a useful example of galaxy evolution in action. The authors say it shows that the growth of galaxies is not peaceful or gradual but rather a battle between the explosive power of black holes and the crushing pressure of the environments they live in.

By studying this galaxy, astronomers are gaining rare insight into:

  • How often black holes switch between active and quiet phases

  • How old radio plasma interacts with hot cluster gas

  • How repeated eruptions can transform a galaxy’s surroundings over cosmic time

The research team now plans to use more sensitive, high-resolution observations to zoom even deeper into the core of J1007+3540 and track how the restarted jets propagate through this turbulent environment.

Understanding systems like J1007+3540 helps scientists piece together how galaxies grow, shut down, and awaken again, and how huge cosmic environments can shape, bend, distort, and even suffocate the jets that try to escape from their central engine.




Media contacts:

Sam Tonkin
Royal Astronomical Society
Mob: +44 (0)7802 877 700

press@ras.ac.uk

Science contacts:

Shobha Kumari
Midnapore City College in India

shobhakumari@mcconline.org.in



Further information

The paper ‘Probing AGN duty cycle and cluster-driven morphology in a giant episodic radio galaxy’ by S. Kumari et al. has been published in Monthly Notices of the Royal Astronomical Society. DOI: 10.1093/mnras/staf2038.



Notes for editors

About the Royal Astronomical Society

The Royal Astronomical Society (RAS), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science.

The RAS organises scientific meetings, publishes international research and review journals, recognises outstanding achievements by the award of medals and prizes, maintains an extensive library, supports education through grants and outreach activities and represents UK astronomy nationally and internationally. Its more than 4,000 members (Fellows), a third based overseas, include scientific researchers in universities, observatories and laboratories as well as historians of astronomy and others.

The RAS accepts papers for its journals based on the principle of peer review, in which fellow experts on the editorial boards accept the paper as worth considering. The Society issues press releases based on a similar principle, but the organisations and scientists concerned have overall responsibility for their content.

Keep up with the RAS on Instagram, Bluesky, LinkedIn, Facebook and YouTube.

Download the RAS Supermassive podcast

Submitted by Sam Tonkin on Thu, 15/01/2026 - 10:42


Sunday, January 18, 2026

When Winds Collide: Predicting the Effects of Stream Interaction Regions

Illustration of the solar wind interacting with Earth's magnetic field.
Credit:
NASA's Goddard Space Flight Center

The Solar Heliospheric Observatory (SOHO) took this coronagraphic image of a coronal mass ejection on 20 April 1998.
Credit:
SOHO (ESA & NASA)

What happens when pileups of solar wind plasma collide with Earth’s protective magnetosphere? New work uses machine learning to examine how strongly these events affect our planet’s magnetic field.

Plasma Pileups

Geomagnetic storms driven by solar activity paint night skies with glowing aurorae, but they also threaten spacecraft electronics with showers of high-energy particles. While immense eruptions of solar plasma and magnetic fields called coronal mass ejections are the most infamous example of solar activity, a team led by Yudong Ye (Sun Yat-Sen University) recently focused on another, less destructive form of activity: stream interaction regions.

Stream interaction regions arise when slow-moving solar wind is struck from behind by faster-moving solar wind emitted later. The collision of the two solar wind streams creates a tangle of compressed plasma and strong magnetic fields capable of peeling back Earth’s protective magnetosphere and dumping in high-energy charged particles, with beautiful yet harmful results.

Illustration of the authors’ support vector machine framework. The optimal hyperplane is the boundary that best divides the data by maximizing the distance between the boundary and the data points nearest to it; these points are called support vectors. Square and triangle symbols represent two classes of data. Click to enlarge. Credit: Ye et al. 2025

Machine Learning Method

Though stream interaction regions are less disruptive than coronal mass ejections, they’re far more common; they frequently needle Earth’s magnetosphere, especially during the calmer years of the Sun’s activity cycle. Predicting how strongly a stream interaction region will influence Earth’s magnetosphere — in other words, how geoeffective it is — is challenging, however. When two streams of solar wind collide, their properties combine in complex and nonlinear ways that traditional statistical investigations have struggled to pin down.

Now, Ye and collaborators have used machine learning to study the properties and impact of stream interaction regions in a physically meaningful way. They performed their study on a sample of 879 stream interaction events for which there is abundant information, such as temperature, magnetic field strength and direction, and solar wind conditions before and after the event.

Ye’s team based their framework on a support vector machine classifier: a classical machine learning algorithm that draws a mathematical boundary between groups of data while maximizing the distance between the boundary and the data points nearest to the dividing line. The support vector machine algorithm is well-suited to the task of modeling the geoeffectiveness of stream interaction regions because it doesn’t require a particularly vast dataset, can tolerate misclassified events, and allows for a physical interpretation of the results.



Illustration of how the interplanetary magnetic field (IMF) interacts with Earth’s magnetosphere. When the IMF points southward, as it does in this diagram, the impact on Earth’s magnetosphere is increased, with magnetic reconnection occurring in the red areas. Credit: NASA

A Physical Interpretation

The team first reined in the model’s complexity by identifying the most important features in the dataset. They then determined which features or combination of features had the largest contribution to the output — in other words, which physical parameters most strongly determined the geoeffectiveness of the event.

Ye and collaborators found that the strongest determinants of an event’s geoeffectiveness were how long the solar wind was directed southward, the strength of the solar wind electric field, and the average and minimum strengths of the southward-pointing solar wind magnetic field. These results align with the current understanding of how energy is transferred from the solar wind to Earth’s magnetosphere through magnetic reconnection, a release of magnetic energy driven by rearrangement of magnetic fields. This shows how classical machine learning methods can enhance our ability to predict the outcome of oncoming space weather while simultaneously examining the physical drivers of the event.

Citation

“Assessing the Geoeffectiveness of Stream Interaction Regions Through Physically Interpretable Machine Learning,” Yudong Ye et al 2025 ApJ 993 10. doi:10.3847/1538-4357/ae0454



Saturday, January 17, 2026

Do Even Low-mass Dwarf Galaxies Merge? New Clues from the Outer Stars of a Milky Way Satellite

Figure 1: Image of the Ursa Minor dwarf spheroidal galaxy (UMi dSph) observed with Hyper Suprime-Cam, covering three fields of view. The red dashed ellipse indicates the central region of the UMi dSph. Although the galaxy is extremely faint and difficult to identify visually, its member stars extend across the entire image. (Credit: NAOJ)

Figure 2: Spatial distribution of member main-sequence stars of the UMi dSph (central panel), and stellar number density profiles along the major and minor axes (left and right panels, respectively). The color map and contours in the central panel both represent the stellar surface density. The white dashed lines indicate the directions of the major and minor axes of the UMi dSph. The black curves in the side panels show the predicted number density profiles assuming no extended stellar structure. The observed number densities (blue and green points) exceed these predictions along both the major and minor axes, indicating the presence of an extended stellar structure in the outskirts. (Credit: NAOJ)




Using the Subaru Telescope’s wide-field camera, astronomers have discovered a previously unknown structure surrounding a tiny satellite galaxy of the Milky Way. The newly discovered structure exhibits features resembling the remnants of past galaxy mergers. This result provides compelling evidence that even extremely low-mass dwarf galaxies may have experienced mergers in their past.

Numerous small satellite galaxies have long been gravitationally bound to the Milky Way, orbiting around it. These dwarf galaxies are often regarded as "fossil galaxies" formed in the early Universe, and their structures provide valuable clues to understanding how galaxies formed and evolved.

Traditionally, dwarf galaxies have been thought to form through relatively simple processes, such as gas inflow and outflow and internal star formation, meaning that galaxy–galaxy interactions or mergers were considered rare in such low-mass systems. However, recent observations by the European Space Agency’s Gaia mission have revealed that in some dwarf galaxies, stars are distributed beyond their expected outer boundary, known as the tidal radius. Because Gaia observations are limited to relatively bright stars, primarily red giant branch (RGB) stars, it has been difficult to investigate the detailed distribution using numerous faint stars in the outer regions. As a result, it has remained unclear whether these extended structures are the result of tidal interactions with the Milky Way or are intrinsic features formed through past galaxy mergers.

An international research team, led by the National Astronomical Observatory of Japan (NAOJ) and including SOKENDAI (The Graduate University for Advanced Studies), Hosei University, and Tohoku University, observed the Ursa Minor dwarf spheroidal galaxy (UMi dSph), a satellite galaxy of the Milky Way, using Hyper Suprime-Cam (HSC) on the Subaru Telescope. By combining one of the world’s widest fields of view, equivalent to nine full moons, with the powerful light-gathering capability of the 8.2-meter telescope, HSC enabled the team to investigate the faint stellar populations of the galaxy out to its outskirts beyond the nominal tidal radius. As a result, the team detected many faint main-sequence stars that were invisible to Gaia and successfully mapped the stellar distribution extending into the outskirts of the UMi dSph with unprecedented precision.

Their analysis reveals that the stellar distribution extends not only along the major axis, as previously known, but also along the minor axis (Figure 2). The structure along the minor axis shows properties distinct from the elongation along the major axis, which is commonly attributed to tidal forces from the Milky Way. This suggests that the minor-axis structure may have a different origin.

The minor-axis structure discovered around the UMi dSph may have been formed through a merger between dwarf galaxies. These findings suggests that galaxy interactions and mergers may have played a role in the formation and evolution of even extremely low-mass dwarf galaxies, with masses as small as one ten-thousandth that of the Milky Way.

Kyosuke Sato, the lead author of this study and a graduate student at SOKENDAI, says, "We have rarely found evidence of galaxy mergers in the Milky Way’s dwarf galaxies. This discovery offers a new way of thinking about how dwarf galaxies formed."

This study has revealed a previously hidden stellar structure in the outskirts of the UMi dSph, representing an important step toward understanding the formation and evolutionary history of dwarf galaxies. However, to determine whether this structure was formed by tidal interactions with the Milky Way or represents a remnant of a past merger, detailed studies of stellar kinematics and chemical abundances are required. Future observations with the Subaru Telescope’s new spectrograph, ʻŌnohiʻula PFS, are expected to reveal the origin of this structure.

This research has been published in The Astrophysical Journal Letters on October 23, 2025 (Sato et al., "The Extended Stellar Distribution in the Outskirts of the Ursa Minor Dwarf Spheroidal Galaxy").

This work was supported by JSPS KAKENHI (Grant Nos. JP18H05875, JP20K04031, JP20H05855, JP25K01047, and JP24K00669) and by JST SPRING, Japan (Grant No. JPMJSP2104). Part of this work was also supported by Oversea Travel Fund (2025) for students of the Astronomical Science Program, The Graduate University for Advanced Studies, SOKENDAI.




About the Subaru Telescope

The Subaru Telescope is a large optical-infrared telescope operated by the National Astronomical Observatory of Japan, National Institutes of Natural Sciences with the support of the MEXT Project to Promote Large Scientific Frontiers. We are honored and grateful for the opportunity of observing the Universe from Maunakea, which has cultural, historical, and natural significance in Hawai`i.


Friday, January 16, 2026

NASA’s Webb Delivers Unprecedented Look Into Heart of Circinus Galaxy

This artist’s concept depicts the central engine of the Circinus galaxy, visualizing the supermassive black hole fed by a thick, dusty torus that glows in infrared light. Credit Artwork: NASA, ESA, CSA, Ralf Crawford (STScI)

This image from NASA’s Hubble Space Telescope shows the Circinus galaxy. A close-up of its core from NASA’s James Webb Space Telescope shows the inner face of the hole of the donut-shaped disk of gas disk glowing in infrared light. The outer ring appears as dark spots. Credit Image: NASA, ESA, CSA, Enrique Lopez-Rodriguez (University of South Carolina), Deepashri Thatte (STScI); Image Processing: Alyssa Pagan (STScI); Acknowledgment: NSF's NOIRLab, CTIO

This image shows two views of the Circinus galaxy, one captured by the Hubble Space Telescope and the other by the James Webb Space Telescope’s NIRISS (Near-Infrared Imager and Slitless Spectrograph. It shows compass arrows, scale bar, and color key for reference. Credit Image: NASA, ESA, CSA, Enrique Lopez-Rodriguez (University of South Carolina), Deepashri Thatte (STScI); Image Processing: Alyssa Pagan (STScI); Acknowledgment: NSF's NOIRLab, CTIO

This zoom-in video shows the location of the Circinus galaxy on the sky. It begins with a ground-based photo of the constellation Circinus by the late astrophotographer Akira Fujii. The video closes in on the Circinus galaxy, using views from the Digitized Sky Survey and the Dark. Credit Video: NASA, ESA, CSA, Alyssa Pagan (STScI); Acknowledgment: CTIO, NSF's NOIRLab, DSS, Akira Fujii



The Circinus Galaxy, a galaxy about 13 million light-years away, contains an active supermassive black hole that continues to influence its evolution. The largest source of infrared light from the region closest to the black hole itself was thought to be outflows, or streams of superheated matter that fire outward.

Now, new observations by NASA’s James Webb Space Telescope, seen here with a new image from NASA’s Hubble Space Telescope, provide evidence that reverses this thinking, suggesting that most of the hot, dusty material is actually feeding the central black hole. The technique used to gather this data also has the potential to analyze the outflow and accretion components for other nearby black holes.

The research, which includes the sharpest image of a black hole’s surroundings ever taken by Webb, published Tuesday in Nature.

Outflow question

Supermassive black holes like those in Circinus remain active by consuming surrounding matter. Infalling gas and dust accumulates into a donut-shaped ring around the black hole, known as a torus. As supermassive black holes gather matter from the torus’ inner walls, they form an accretion disk, similar to a whirlpool of water swirling around a drain. This disk grows hotter through friction, eventually becoming hot enough to emit light.

This glowing matter can become so bright that resolving details within the galaxy’s center with ground-based telescopes is difficult. It’s made even harder due to the bright, concealing starlight within Circinus. Further, since the torus is incredibly dense, the inner region of the infalling material, heated by the black hole, is obscured from our point of view. For decades, astronomers contended with these difficulties, designing and improving models of Circinus with as much data as they could gather.

“In order to study the supermassive black hole, despite being unable to resolve it, they had to obtain the total intensity of the inner region of the galaxy over a large wavelength range and then feed that data into models,” said lead author Enrique Lopez-Rodriguez of the University of South Carolina.

Early models would fit the spectra from specific regions, such as the emissions from the torus, those of the accretion disk closest to the black hole, or those from the outflows, each detected at certain wavelengths of light. However, since the region could not be resolved in its entirety, these models left questions at several wavelengths. For example, some telescopes could detect an excess of infrared light, but lacked the resolution to determine where exactly it was coming from.

“Since the ‘90s, it has not been possible to explain excess infrared emissions that come from hot dust at the cores of active galaxies, meaning the models only take into account either the torus or the outflows, but cannot explain that excess,” said Lopez-Rodriguez.

Such models found that most of the emission (and, therefore, mass) close to the center came from outflows. To test this theory, then, astronomers needed two things: the ability to filter the starlight that previously prevented a deeper analysis, and the ability to distinguish the infrared emissions of the torus from those of the outflows. Webb, sensitive and technologically sophisticated enough to meet both challenges, was necessary to advance our understanding.

Webb’s innovative technique

To look into the center of Circinus, Webb needed the Aperture Masking Interferometer tool on its NIRISS (Near-Infrared Imager and Slitless Spectrograph) instrument.

On Earth, interferometers usually take the form of telescope arrays: mirrors or antennae that work together as if they were a single telescope. An interferometer does this by gathering and combining the light from whichever source it is pointed toward, causing the electromagnetic waves that make up light to “interfere” with each other (hence, “interfere-ometer”) and creating interference patterns. These patterns can be analyzed by astronomers to reconstruct the size, shape, and features of distant objects with much greater detail than non-interferometric techniques.

The Aperture Masking Interferometer allows Webb to become an array of smaller telescopes working together as an interferometer, creating these interference patterns by itself. It does this by utilizing a special aperture made of seven small, hexagonal holes, which, like in photography, controls the amount and direction of light that enters the telescope’s detectors.

“These holes in the mask are transformed into small collectors of light that guide the light toward the detector of the camera and create an interference pattern,” said Joel Sanchez-Bermudez, co-author based at the National University of Mexico.

With new data in hand, the research team was able to construct an image from the central region's interference patterns. To do so, they referenced data from previous observations to ensure their data from Webb was free of any artifacts. This resulted in the first extragalactic observation from an infrared interferometer in space.

"By using an advanced imaging mode of the camera, we can effectively double its resolution over a smaller area of the sky," Sanchez-Bermudez said. "This allows us to see images twice as sharp. Instead of Webb’s 6.5-meter diameter, it’s like we are observing this region with a 13-meter space telescope."

The data showed that contrary to the models predicting that the infrared excess comes from the outflows, around 87% of the infrared emissions from hot dust in Circinus come from the areas closest to the black hole, while less than 1% of emissions come from hot dusty outflows. The remaining 12% comes from distances farther away that could not previously be told apart.

“It is the first time a high-contrast mode of Webb has been used to look at an extragalactic source,” said Julien Girard, paper co-author and senior research scientist at the Space Telescope Science Institute. “We hope our work inspires other astronomers to use the Aperture Masking Interferometer mode to study faint, but relatively small, dusty structures in the vicinity of any bright object.”

Universe of black holes

While the mystery of Circinus’ excess emissions has been solved, there are billions of black holes in our universe. Those of different luminosities, the team notes, may have an influence on whether most of the emissions come from a black hole’s torus or their outflows.

“The intrinsic brightness of Circinus’ accretion disk is very moderate,” Lopez-Rodriguez said. “So it makes sense that the emissions are dominated by the torus. But maybe, for brighter black holes, the emissions are dominated by the outflow.”

With this research, astronomers now have a tested technique to investigate whichever black holes they want, so long as they are bright enough for the Aperture Masking Interferometer to be useful. Studying additional targets will be essential to building a catalog of emission data to figure out if Circinus’ results were unique or characteristic of a pattern.

“We need a statistical sample of black holes, perhaps a dozen or two dozen, to understand how mass in their accretion disks and their outflows relate to their power,” Lopez-Rodriguez said.

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).




Related Links

Read more: The Modes of Webb’s NIRISS

Explore more: Black Hole Resources from NASA’s Universe of Learning

Read more: Webb’s Scientific Instruments

Video: NASA Animation Sizes Up the Universe’s Biggest Black Holes

More Webb News

More Webb Images

Webb Science Themes

Webb Mission Page



Location: NASA Goddard Space Flight Center

Contact:

Media

Laura Betz
NASA’s Goddard Space Flight Center
Greenbelt, Maryland

laura.e.betz@nasa.gov

Matthew Brown
Space Telescope Science Institute
Baltimore, Maryland


Hannah Braun
Space Telescope Science Institute
Baltimore, Maryland




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