The Universe’s Secret Harvest: ALMA Sheds Light on “the Cosmic Grapes”

An artist’s impression of the “Cosmic Grapes” galaxy, composed of at least 15 massive star forming clumps—far more than current theoretical models predict could exist within a single rotating disk at this early time. Image credit NSF/AUI/NSF NRAO/B.Saxton.Credit: NSF/AUI/NSF NRAO/B. Saxton. Hi-Res File

The Cosmic Grapes initially appeared in past HST data as a typical galaxy with a smooth stellar disk (left). However, deep, high-resolution follow-up observations by JWST (middle) and ALMA (right) revealed that it actually consists of numerous compact stellar clumps embedded within a smooth, rotating gas disk. The red and blue colors in the right panel represent redshifted and blueshifted gas motions, respectively, tracing the rotation of the disk. Credit: NSF/AUI/NSF NRAO/B. Saxton. Hi-Res File

The Cosmic Grapes initially appeared in past HST data as a typical galaxy with a smooth stellar disk (left). However, deep, high-resolution follow-up observations by JWST (middle) and ALMA (right) revealed that it actually consists of numerous compact stellar clumps embedded within a smooth, rotating gas disk. The red and blue colors in the right panel represent redshifted and blueshifted gas motions, respectively, tracing the rotation of the disk. Credit: Data images noted from specific instruments, assemble by NSF/AUI/NSF NRAO/B.Saxton. Hi-Res File

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ALMA and JWST observations unveil unexpected details of rapid growth in a faint, newborn “grape-like” galaxy, similar to galaxies in the early universe following the Big Bang

Astronomers have discovered a remarkably clumpy rotating galaxy that existed just 900 million years after the Big Bang, shedding new light on how galaxies grew and evolved in the early universe. Nicknamed the “Cosmic Grapes,” the galaxy appears to be composed of at least 15 massive star-forming clumps—far more than current theoretical models predict could exist within a single rotating disk at this early time.

The discovery was made possible by an extraordinary combination of observations from the Atacama Large Millimeter/submillimeter Array (ALMA) and the James Webb Space Telescope (JWST), all focused on a single galaxy that happened to be perfectly magnified by a foreground galaxy cluster through gravitational lensing. In total, more than 100 hours of telescope time were dedicated to this single system, making it one of the most intensively studied galaxies from the early universe.

Although the galaxy had appeared as a smooth, single disk-like object in previous Hubble images, the powerful resolution of ALMA and JWST, enhanced by gravitational lensing, revealed a dramatically different picture: a rotating galaxy teeming with massive clumps, resembling a cluster of grapes. The finding marks the first time astronomers have linked small-scale internal structures and large-scale rotation in a typical galaxy at cosmic dawn, reaching spatial resolutions down to just 10 parsecs (about 30 light-years).

This galaxy does not represent a rare or extreme system. It lies squarely on the “main sequence” of galaxies in terms of its star forming activity, mass, size, chemical composition—meaning it is likely representative of a broader population. If so, many other seemingly smooth galaxies seen by current facilities may actually be made up of similar unseen substructures, hidden by the limits of current resolution.

Because existing simulations fail to reproduce such a large number of clumps in rotating galaxies at early times, this discovery raises key questions about how galaxies form and evolve. It suggests that our understanding of feedback processes and structure formation in young galaxies may need significant revision. The Cosmic Grapes now offer a unique window into the birth and growth of galaxies — and may be just the first of many. Future observations will be key to revealing whether such clumpy structures were common in the universe’s youth.

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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A sea monster and a Tarantula

A nebula. The top-left is dense with layers of fluffy pink and greenish clouds. Long strands of green clouds stretch out from here; a faint layer of translucent blue dust combines with them to create a three-dimensional scene. A sparse network of dark dust clouds in the foreground adds reddish-black patches atop the nebula. Blue-white and orange stars, from our galaxy and beyond, are spread amongst the clouds. Credit: ESA/Hubble & NASA, C. Murray

A scene from a star-forming factory shines in this NASA/ESA Hubble Space Telescope Picture of the Week. This Hubble picture captures incredible details in the dusty clouds in a star-forming region called the Tarantula Nebula. What’s possibly the most amazing aspect of this detailed image is that this nebula isn’t even in our galaxy. Instead, it’s in the Large Magellanic Cloud, a dwarf galaxy that is located about 160 000 light-years away in the constellations Dorado and Mensa.

The Large Magellanic Cloud is the largest of the dozens of small satellite galaxies that orbit the Milky Way. The Tarantula Nebula is the largest and brightest star-forming region not just in the Large Magellanic Cloud, but in the entire group of nearby galaxies to which the Milky Way belongs.

The Tarantula Nebula is home to the most massive stars known, some of which are roughly 200 times as massive as our Sun. The scene pictured here is located away from the centre of the nebula, where there is a super star cluster called R136, but very close to a rare type of star called a Wolf–Rayet star. Wolf–Rayet stars are massive stars that have lost their outer shell of hydrogen and are extremely hot and luminous, powering dense and furious stellar winds.

This nebula is a frequent target for Hubble, whose multiwavelength capabilities are critical for capturing sculptural details in the nebula’s dusty clouds. The data used to create this image come from an observing programme called Scylla, named for a multi-headed sea monster from the Greek myth of Ulysses. The Scylla programme was designed to complement another Hubble observing programme called ULYSSES (Ultraviolet Legacy library of Young Stars as Essential Standards). ULYSSES targets massive young stars in the Small and Large Magellanic Clouds, while Scylla investigates the structures of gas and dust that surround these stars.

Source: ESA/Hubble/potw

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A fresh look at a classic deep field

An area of deep space with thousands of galaxies in various shapes and sizes on a black background. Most are circles or ovals, with a few spirals. More distant galaxies are smaller, down to being mere dots, while closer galaxies are larger and some appear to be glowing. Red and orange galaxies contain more dust or more stellar activity. Credit: ESA/Webb, NASA & CSA, G. Östlin, P. G. Perez-Gonzalez, J. Melinder, the JADES Collaboration, the MIDIS collaboration, M. Zamani (ESA/Webb)

This image from the NASA/ESA/CSA James Webb Space Telescope revisits one of the most iconic regions of the sky, the Hubble Ultra Deep Field, through the eyes of two of Webb’s instruments. The result is a detailed view that reveals thousands of distant galaxies, some dating back to the earliest periods of cosmic history.

The field shown here, known as the MIRI Deep Imaging Survey (MIDIS) region, was observed with the three shortest-wavelength filters of Webb’s Mid-Infrared Instrument (MIRI) for nearly 100 hours in total. This included Webb's longest observation of an extragalactic field in one filter so far, producing one of the deepest views ever obtained of the Universe. Combined with data from Webb’s Near-Infrared Camera (NIRCam), this image allows astronomers to explore how galaxies formed and evolved over billions of years.

These deep observations have revealed more than 2500 sources in this tiny patch of sky. Among them are hundreds of extremely red galaxies — some of which are likely massive, dust-obscured systems or evolved galaxies with mature stars that formed early in the Universe’s history. Thanks to Webb’s sharp resolution, even at mid-infrared wavelengths, researchers can resolve the structures of many of these galaxies and study how their light is distributed, shedding light on their growth and evolution.

In this image, the colours that have been assigned to different kinds of infrared light highlight the fine distinctions astronomers can make with this deep data. Orange and red represent the longest mid-infrared wavelengths. The galaxies in these colours have extra features — such as high concentrations of dust, copious star formation, or an active galactic nucleus (AGN) at their centre — which emit more of this farther infrared light. Small, greenish-white galaxies are particularly distant, with high redshift. This shifts their light spectrum into the peak mid-infrared wavelengths of the data, which are depicted in white and green. Most of the galaxies in this image lack any such mid-infrared boosting features, leaving them most bright at shorter near-infrared wavelengths, which are depicted with blue and cyan colours.

By returning to this legacy field first made famous by the NASA/ESA Hubble Space Telescope, Webb is continuing and expanding the deep field tradition — revealing new details, uncovering previously hidden galaxies, and offering fresh insights into the formation of the first cosmic structures.

The MIRI observations were taken as part of the Webb programmes #1283 and #6511 (PI: G. Östlin).

Source: ESA/Webb/potm

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Link

• Science paper (G. Östlin et al.)
• Slider Tool
• Pan Video
• Transition video (with Hubble Ultra Deep Field)

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The Milky Way could be teeming with more satellite galaxies than previously thought

The dark matter distribution of a Milky Way mass halo in a Lambda-cold dark matter (LCDM) cosmological simulation. This is the highest resolution simulation of a MW-mass dark matter halo ever performed, called Aquarius-A-L1. The MW halo (in the centre) is surrounded by myriad substructures, a key prediction of the "cold dark matter” model. Some of these subhalos host a satellite galaxy within them that could be observable. Credit: The Aquarius simulation, the Virgo Consortium/Dr Mark Lovell
Licence type: Attribution (CC BY 4.0)

The Milky Way could have many more satellite galaxies than scientists have previously been able to predict or observe, according to new research.

Cosmologists at Durham University used a new technique combining the highest-resolution supercomputer simulations that exist, alongside novel mathematical modelling, predicting the existence of missing "orphan" galaxies.

Their findings suggest that there should be 80 or perhaps up to 100 more satellite galaxies surrounding our home galaxy, orbiting at close distances.

If these galaxies are seen by telescopes then it could provide strong support for the Lambda Cold Dark Matter (LCDM) theory which explains the large-scale structure of the universe and how galaxies form.

This ongoing research is being presented today (Friday 11 July) at the Royal Astronomical Society's National Astronomy Meeting at Durham University.

The research is based on the LCDM model where ordinary matter in the form of atoms represents only 5 per cent of the universe’s total content, 25 per cent is cold dark matter (CDM), and the remaining 70 per cent is dark energy.

In this model, galaxies form in the centre of gigantic clumps of dark matter called halos. Most galaxies in the universe are low-mass dwarf galaxies, the majority of which are satellites orbiting around a more massive galaxy, such as our Milky Way.

The existence of these enigmatic objects has long posed challenges to LCDM – otherwise known as the standard model of cosmology. According to LCDM theory, many more Milky Way companion galaxies should exist than cosmological simulations have so far produced, or astronomers have been able to see.

An artist’s concept of the Milky Way galaxy.
NASA/JPL-Caltech
Licence type: Attribution (CC BY 4.0)

This included the Aquarius simulation, produced by the Virgo Consortium. Aquarius is the highest resolution simulation of a Milky Way dark matter halo ever created and is used to understand the fine-scale structure predicted around the Milky Way.

It also included the GALFORM model, a cutting-edge code developed at Durham over the past two decades which follows the detailed physical processes that are responsible for the formation and evolution of galaxies.

Their results showed that halos of dark matter, which may host a satellite galaxy, have been orbiting around the central Milky Way halo for most of the age of the universe, leading to the stripping of their dark matter and stellar mass, and rendering them extremely small and faint.

As a result, the research predicts that the total number of satellite galaxies – of any brightness – likely to exist around the Milky Way is around 80 or potentially up to 100 more than currently known.

The research puts particular emphasis on the approximately 30 newly discovered tiny Milky Way satellite candidates that are extremely faint and small.

Scientists are unclear if these are dwarf galaxies embedded in a dark matter halo, or globular clusters, collections of self-gravitating stars.

The Durham researchers argue that these objects could be a subset of the faint population of satellite galaxies they predict should exist.

Co-researcher Professor Carlos Frenk, of the Institute for Computational Cosmology, Department of Physics, Durham University said: "If the population of very faint satellites that we are predicting is discovered with new data, it would be a remarkable success of the LCDM theory of galaxy formation.

"It would also provide a clear illustration of the power of physics and mathematics. Using the laws of physics, solved using a large supercomputer, and mathematical modelling we can make precise predictions that astronomers, equipped with new, powerful telescopes, can test. It doesn't get much better than this."

The research is funded by the European Research Council through an Advanced Investigator grant to Professor Frenk, and by the Science and Technology Facilities Council (STFC). The calculations were performed on the Cosmology Machine (COSMA), a supercomputer supported by the STFC's Distributed Infrastructure for Research using Advanced Computing (DiRAC) project, and hosted by Durham University. The new research shows that the Milky Way's missing satellites are extremely faint galaxies stripped almost entirely of their parent dark matter halos by the gravity of the Milky Way’s halo. These so-called "orphan" galaxies are lost in most simulations, but should have survived in the real universe.

Using their new technique, the Durham researchers were able to track the abundance, distribution, and properties of these Milky Way orphan galaxies – showing that many more Milky Way satellites should exist and be observable today. It is hoped that new advances in telescopes and instruments like the Rubin Observatory LSST camera (which recently saw its first light), will give astronomers the ability to detect these very faint objects, bringing them into our view for the first time.

The dark matter distribution of a Milky Way mass halo in a Lambda-cold dark matter (LCDM) cosmological simulation. This is the highest resolution simulation of a MW-mass dark matter halo ever performed, called Aquarius-A-L1. The MW halo (in the centre) is surrounded by myriad substructures, a key prediction of the "cold dark matter” model. Some of these subhalos host a satellite galaxy within them that could be observable. The new predicted Milky Way “orphan satellite” galaxies are marked with an 'x' symbol. The Aquarius simulation, the Virgo Consortium/Dr Mark Lovell

Licence type: Attribution CC BY 4.0)

Lead researcher Dr Isabel Santos-Santos, in the Institute for Computational Cosmology, Department of Physics, Durham University, said: "We know the Milky Way has some 60 confirmed companion satellite galaxies, but we think there should be dozens more of these faint galaxies orbiting around the Milky Way at close distances.

"If our predictions are right, it adds more weight to the Lambda Cold Dark Matter theory of the formation and evolution of structure in the universe.

"Observational astronomers are using our predictions as a benchmark with which to compare the new data they are obtaining.

"One day soon we may be able to see these 'missing' galaxies, which would be hugely exciting and could tell us more about how the universe came to be as we see it today."

The concept of LCDM is the cornerstone of our understanding of the universe. It has led to the Standard Model of Cosmology and is the most widely accepted model for describing the universe's evolution and structure on large scales.

The model has passed multiple tests but has recently been challenged by puzzling observational data on dwarf galaxies.

The Durham researchers say that even the best existing cosmological simulations (which include gas and star formation, in addition to dark matter) do not have the resolution needed to study galaxies as faint as those astronomers are starting to discover close to the Milky Way.

These simulations also lack the precision required to follow the evolution of the small dark matter halos that host the dwarf galaxies as they orbit around the Milky Way over billions of years.

This leads to the artificial disruption of some halos, leaving galaxies "orphaned". Although the simulations lose the halos of "orphan" galaxies, such galaxies should survive in the real universe.

An artist’s concept of the Milky Way galaxy. Credit: NASA/JPL-Caltech
Licence type: Attribution (CC BY 4.0)

The Durham researchers combined cosmological supercomputer simulations with analytical models to overcome these numerical issues.

This included the Aquarius simulation, produced by the Virgo Consortium. Aquarius is the highest resolution simulation of a Milky Way dark matter halo ever created and is used to understand the fine-scale structure predicted around the Milky Way.

It also included the GALFORM model, a cutting-edge code developed at Durham over the past two decades which follows the detailed physical processes that are responsible for the formation and evolution of galaxies.

Their results showed that halos of dark matter, which may host a satellite galaxy, have been orbiting around the central Milky Way halo for most of the age of the universe, leading to the stripping of their dark matter and stellar mass, and rendering them extremely small and faint.

As a result, the research predicts that the total number of satellite galaxies – of any brightness – likely to exist around the Milky Way is around 80 or potentially up to 100 more than currently known.

The research puts particular emphasis on the approximately 30 newly discovered tiny Milky Way satellite candidates that are extremely faint and small.

Scientists are unclear if these are dwarf galaxies embedded in a dark matter halo, or globular clusters, collections of self-gravitating stars.

The Durham researchers argue that these objects could be a subset of the faint population of satellite galaxies they predict should exist.

Co-researcher Professor Carlos Frenk, of the Institute for Computational Cosmology, Department of Physics, Durham University said: "If the population of very faint satellites that we are predicting is discovered with new data, it would be a remarkable success of the LCDM theory of galaxy formation.

"It would also provide a clear illustration of the power of physics and mathematics. Using the laws of physics, solved using a large supercomputer, and mathematical modelling we can make precise predictions that astronomers, equipped with new, powerful telescopes, can test. It doesn't get much better than this."

The research is funded by the European Research Council through an Advanced Investigator grant to Professor Frenk, and by the Science and Technology Facilities Council (STFC).

The calculations were performed on the Cosmology Machine (COSMA), a supercomputer supported by the STFC's Distributed Infrastructure for Research using Advanced Computing (DiRAC) project, and hosted by Durham University.

 

Submitted by Sam Tonkin

Source: Royal Astronomical Society (RAS)/News and Press

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Media contacts:

Sam Tonkin
Royal Astronomical Society
Mob: +44 (0)7802 877 700
press@ras.ac.uk

Dr Robert Massey
Royal Astronomical Society
Mob: +44 (0)7802 877 699
press@ras.ac.uk

Megan Eaves
Royal Astronomical Society
press@ras.ac.uk

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Science contacts:

Dr Isabel Santos
Durham University
isabel.santos@durham.ac.uk

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Further information

The talk ‘The contribution of "orphan" galaxies to the ultrafaint population of MW satellites’ will take place at NAM at 10:15 BST on Friday 11 July 2025 in room TLC106. Find out more at: https://conference.astro.dur.ac.uk/event/7/contributions/515/

Notes for editors

The NAM 2025 conference is principally sponsored by the Royal Astronomical Society and Durham University.

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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

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About the Science and Technology Facilities Council

The Science and Technology Facilities Council (STFC), part of UK Research and Innovation (UKRI), is the UK’s largest public funder of research into astronomy and astrophysics, particle and nuclear physics, and space science. We operate five national laboratories across the UK which, supported by a network of additional research facilities, increase our understanding of the world around us and develop innovative technologies in response to pressing scientific and societal issues. We also facilitate UK involvement in a number of international research activities including the ELT, CERN, the James Webb Space Telescope and the Square Kilometre Array Observatory.

linkedin.com/company/stfc

ukri.org/councils/stfc

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About Durham University

Durham University is a globally outstanding centre of teaching and research based in historic Durham City in the UK.

We are a collegiate university committed to inspiring our people to do outstanding things at Durham and in the world.

We conduct research that improves lives globally and we are ranked as a world top 100 university with an international reputation in research and education (QS World University Rankings 2026).

We are a member of the Russell Group of leading research-intensive UK universities and we are consistently ranked as a top five university in national league tables (Times and Sunday Times Good University Guide and The Complete University Guide).

For more information about Durham University visit: www.durham.ac.uk/about/

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Gravitational Waves from Stars Stripped by Supermassive Black Holes?

Formation of the System

Cartoon of the system's key evolutionary stages. Top left: a binary enters the supermassive black hole's Hill sphere and is disrupted. One star is captured on an eccentric orbit, the other ejected as a hyper-velocity star. Top right: the captured star's orbit shrinks and circularizes via gravitational wave emission. Bottom left: the sub-giant star begins stable mass transfer onto the supermassive black hole. Bottom right: after losing its hydrogen envelope, the compact core continues inspiraling via gravitational wave emission, eventually becoming a loud LISA-band source. Adopted from Olejak et al. 2025.

Imagine a star not crashing into a supermassive black hole in a fiery explosion, but instead slowly spiraling in, circling closer and closer to its horizon. This is the story of a sub-giant star that is stripped of its hydrogen layer by a black hole companion with a few million solar masses. The left-over helium core is gently drawn in due to strong gravitational wave emission and can be placed so close to the supermassive black hole that it becomes a promising gravitational wave source for the future detector LISA (Laser Interferometer Space Antenna). This scenario has been recently investigated by a team at MPA.

The story begins with two stars in a binary system that drift too close to a supermassive black hole. The black hole’s powerful gravity tears them apart through the so-called Hills mechanism (see Fig. 1): One star is flung out at incredible speed (a so-called hyper-velocity star), while the other star is captured to orbit the black hole on a highly eccentric orbit. If the separation of the captured star is in a certain regime, gravitational waves will lead to gradual circularization and decay of the orbit (see Fig.1). As a consequence, the star will finally start to transfer mass onto the supermassive black hole on a relatively circular orbit.

If the captured star is a so called sub-giant, relatively soon after its main sequence phase (i.e. the end of its core hydrogen burning), it has already developed a helium core. Such a star may lose its outer layers to the supermassive black hole companion and be stripped – slowly but steadily – down to its helium-rich core (Fig.1).

Gravitational wave signal from a sub-giant (with initially 2 solar masses) transferring matter to a 4.3 million solar mass supermassive black hole, plotted against the gravitational wave frequency. The coloured curve shows the signal if the system is in the Milky Way, with time counting back from the final tidal disruption of the core (red star symbol). The colour scale indicates the signal-to-noise ratio of the gravitational wave signal, which can reach up to a million for the final disruption. Gray lines show more distant cases (up to 1 Gpc) and the solid black line (red dashed line) indicates the LISA sensitivity curve for a 4-year mission, showing that such a system would be detectable up to ~1 Gpc. Adopted from Olejak et al. 2025.

A Slow, Steady Spiral Inward

Unlike in the dramatic tidal disruption events often observed in galactic centers, where a star on a highly eccentric orbit might be ripped apart in one go, the mass transfer process investigated in this study happens over hundreds of thousands or millions of years. The star doesn’t disappear right away. Instead, it gradually loses mass, becoming a stripped helium core, and spirals inward.

Such a stripped core is compact enough that it can get very close to the supermassive black hole, at a separation comparable to the size of the black hole’s Schwarzschild radius. As the helium-core star slowly spirals in, it sends out a gravitational wave signal with gradually increasing frequency that space-based detectors like LISA are designed to pick up.

Moreover, every now and then, the core might light up again due to hydrogen reignition on the residual hydrogen-rich surface. Accompanying brief bursts of X-rays might be the visible sign of what’s happening – and a counterpart to the gravitational wave signal. If the spin of the supermassive black hole is sufficiently high, the final disruption of the helium core will happen near the so-called ‘innermost stable orbit’. This could be observable via both electromagnetic and gravitational wave emission, making it a very exciting multi-messenger transient.

These objects could be among the brightest gravitational wave sources in the Milky Way. Due to their loudness, they might also be detectable from large distances in the local Universe (see Fig. 2). In its several-year mission, LISA could detect dozens of them; hopefully even one right at the center of our own galaxy (with a chance of about 1%).

Illustration of a black hole stripping a star.
Credit: NASA/JPL-Caltech

A New Window into the Heart of Galaxies

The system described here is an example of a so-called ‘extreme mass ratio inspiral’ (due to the huge mass asymmetry between the star and the supermassive black hole). Such systems offer a unique opportunity to study the surroundings of supermassive black holes. Detecting one would not only shed light on how stars evolve in these exotic environments, but also on how they can feed black holes over extended timescales. Unlike typical interactions involving stellar-mass black holes, these systems may also produce short X-ray bursts from hydrogen flashes and end in a final tidal disruption.

This makes them promising candidates for multi-messenger astronomy, potentially linking gravitational wave signals with electromagnetic observations and offering a richer, more complete view of our universe.

Source: Max Planck Institute for Astrophysics

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Author:
Image of Dr. Aleksandra Olejak
Olejak, Aleksandra
Postdoc
tel:2231
aolejak@mpa-garching.mpg.de

Original publication

Aleksandra Olejak et al.
Supermassive Black Holes Stripping a Subgiant Star Down to Its Helium Core: A New Type of Multimessenger Source for LISA

2025 ApJL 987 L11

DOI

More Information

LISA
Website of the Laser Interferometer Space Antenna

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NuSTAR Observes a Nearby Supernova

An astrophotographer's optical image of the supernova host galaxy NGC 7331. SN 2025rbs is visible as a bright point close to the galaxy center. An animated GIF showing the appearance of the supernova can be found at: https://ssr.app.astrobin.com/i/pnplmb?r=C. Image credit: GalacticRAVE/M. Steinmetz. Download Image

During the past week, NuSTAR responded to a community target-of-opportunity (ToO) request to observe the young, Type Ia supernova SN 2025rbs, which is located in the galaxy NGC 7331. Type Ia supernovae are the result of a white dwarf accreting material from a companion star until it exceeds the Chandrasekhar mass and explodes. These explosions have regular enough time profiles and overall luminosity that they are regularly used to measure the distance scale of the Universe. However, their underlying physics is relatively poorly understood since there are few Type Ia supernovae that are close enough to study in detail. In their early lives, the supernovae are powered by radioactive decay of material (primarily 56Ni) that releases gamma-rays that thermalize into the supernova atmosphere so that the ejecta glows in optical light. NuSTAR provides a unique capability to study the hard X-ray (>50 keV) emission from these systems, which arises as the ejecta expands and becomes optically thin to the gamma-ray photons so that hard X-rays “leak out” of the ejecta. SN 2025rbs is the closest Type Ia supernova to the Earth since SN 2014J exploded in M82, which NuSTAR observed in January/February 2014 for nearly a month. The NuSTAR ToO observation of SN 2025rbs occurred prior to the optical peak of the emission, only six days after the supernova was classified as a Type Ia and a few days before the optical peak. An Astronomer’s Telegram (ATel) reporting early results was posted the same day the data were received at the NuSTAR Science Operations Center (SOC), thanks to the ability of the SOC to provide “quicklook” unprocessed data products to the community. These data will provide the most stringent limits on any high-energy emission from the supernova explosion.

Authors: Brian Grefenstette (NuSTAR Instrument Scientist, Caltech)

Source:  NASA's Nuclear Spectroscopic Telescope Array (NuSTAR)

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Chandra X-Ray Observatory Captures Breathtaking New Images

 

The images feature data from the Smithsonian Astrophysical Observatory along with a host of other NASA telescopes including the James Webb Space Telescope, Hubble Space Telescope and more.

Top row:

N79 is a giant region of star formation in the Large Magellanic Cloud, a small satellite neighbor galaxy to the Milky Way. Chandra sees the hot gas created by young stars, which helps astronomers better understand how stars like our Sun formed billions of years ago. [X-rays from Chandra (purple) and infrared data from Webb (blue, grey and gold)]

NGC 2146 is a spiral galaxy with one of its dusty arms obscuring the view of its center from Earth.. X-rays from Chandra reveal double star systems and hot gas being expelled from the galaxy by supernova explosions and strong winds from giant stars. [X-rays from Chandra (pink and purple), optical data from Hubble and the Las Cumbres Observatory in Chile and infrared data from NSF’s Kitt Peak (red, green and blue)]

IC 348 is a star-forming region in our Milky Way galaxy. The wispy structures that dominate the image are interstellar material that reflects light from the cluster’s stars. The point-like sources in Chandra’s X-ray data are young stars forming in the cluster. [X-rays from Chandra (red, green and blue) and Webb infrared data (pink, orange and purple)]

Middle row:

M83, a spiral galaxy similar to the Milky Way, is oriented face-on toward Earth, providing an unobstructed view of its entire structure that is often not possible with galaxies viewed atdifferent angles. Chandra has detected the explosions of stars, or supernovas, and their aftermath across M83. [X-rays from Chandra (red, green and blue) with ground-based optical data (pink, gold and gray)].

M82 is a so-called starburst galaxy where stars are forming at rates tens to hundreds of times higher than normal galaxies. Chandra sees supernovas that produce expanding bubbles of multimillion-degree gas that extend for millions of light-years away from the galaxy's disk. [X-rays from Chandra (purple) with Hubble optical data (red, green, and blue)]

NGC 1068 is a relatively nearby spiral galaxy containing a black hole at its center that is twice as massive as the one in the Milky Ways. Chandra shows a million-mile-per-hour wind is being driven from NGC 1068’s black hole which lights (?) up the center of the galaxy in X-rays. [X-rays from Chandra (blue), radio data from NSF’s VLA radio data (pink), and optical data from Hubble and Webb (yellow, grey and gold)]

Bottom row:

NGC 346 is a young cluster home to thousands of newborn stars. The cluster’s most massive stars createpowerful winds and produce intense radiation. X-rays from Chandra reveal output from massive stars in the cluster and diffuse emission from a supernova remnant, the glowing debris of an exploded star. [X-rays from Chandra (purple) with optical and ultraviolet from Hubble blue, brown and gold)]

IC 1623 is a system where two galaxies are erging. As the galaxies collide, they trigger new bursts of star formation that glow intensely in certain kinds of light which is detected by Chandara and other telescopesThe merging galaxies may also be in the process of forming a supermassive black hole. [X-rays from Chandra (magenta) with Webb infrared data (red, gold and gray)]

Westerlund 1 is the biggest and closest “super” star cluster to Earth. Data from Chandra and other telescopes is helping astronomers delve deeper into this galactic factory where stars are being produced at extraordinarily high rates. Observations from Chandra have uncovered thousands of individual stars pumping out X-ray emission into the cluster. [X-rays from Chandra (pink, blue, purple and orange) with Webb infrared data (yellow, gold and blue) and Hubble optical data (cyan, grey and light yellow)]

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

Source: Harvard-Smithsonian Center for Astrophysics (CfA)/News

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Media Contact:

Megan Watzke
Chandra X-Ray Observatory
mwatzke@cfa.harvard.edu

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Image Credits:

NGC 2146: X-ray: NASA/CXC/SAO; Optical: NASA/ESA/STScI and NOIRLab/NSF/AURA; Infrared: NSF/NOAO/KPNO; Image Processing: NASA/CXC/SAO/L. Frattare

IC 348: X-ray: NASA/CXC/SAO; Infrared: NASA/ESA/CSA/STScI; Image Processing: NASA/CXC/SAO/J. Major

M83: X-ray: NASA/CXC/SAO; Optical: NASA/ESA/AURA/STScI, Hubble Heritage Team, W. Blair (STScI/Johns Hopkins University) and R. O'Connell (University of Virginia); Image Processing: NASA/CXC/SAO/L. Frattare

M82: X-ray: NASA/CXC/SAO; Optical/IR: NASA/ESA/STScI; Image Processing: NASA/CXC/SAO/J. Major

NGC 1068: X-ray: NASA/CXC/SAO; Optical/IR: NASA/ESA/CSA/STScI (HST and JWST); Radio: NSF/NRAO/VLA; Image Processing: NASA/CXC/SAO/J. Schmidt and N. Wolk

NGC 346: X-ray: NASA/CXC/SAO; Optical/IR: NASA/ESA/CSA/STScI (HST and JWST); Radio: NSF/NRAO/VLA; Image Processing: NASA/CXC/SAO/J. Schmidt and N. Wolk

IC 1623: X-ray: NASA/CXC/SAO; IR: NASA/ESA/CSA/STScI; Image Processing: NASA/CXC/SAO/L. Frattare and J. Major

Westerlund 1: X-ray: NASA/CXC/SAO; Optical: NASA/ESA/STScI; IR: NASA/ESA/CSA/STScI; Image Processing: NASA/CXC/SAO/L. Frattare

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Semi-heavy water ice detected around young Sun-like star

JWST image of the protostellar system L1527 IRS. The protostar is, embedded within a cloud of dust, gas and ice (including semi-heavy water ice), which feeds its growth. © NASA/ESA/CSA/STScI

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For the first time, a team at Leiden University led by Ewine van Dishoek, an external scientific member of MPE, has robustly detected semi-heavy water ice around a young, sun-like star. These results support the theory that some of the water in our solar system originated before the Sun and its planets formed. The researchers used the James Webb Space Telescope to make their discovery, which they have published in The Astrophysical Journal Letters.

One way astronomers trace the origin of water is by measuring its deuteration ratio. Deuterium is a stable isotope of hydrogen whose nucleus contains a neutron as well as the proton. Water composed of one deuterium atom and one hydrogen atom – HDO rather than H₂O – is also known as semi-heavy water. A high fraction of semi-heavy water indicates that the water formed in a very cold place, such as the primitive dark clouds of dust, ice, and gas from which stars are born.

In our oceans, comets, and icy moons, up to one in a couple of thousand water molecules consists of semi-heavy water. This is about ten times higher than expected based on the composition of the Sun. Therefore, astronomers hypothesise that some of the water pin our solar system originated as ice in dark clouds hundreds of thousands of years before the birth of the Sun. To confirm this, they must measure the deuteration ratio of water ice in star-forming regions.

An international team of astronomers has now detected a high ratio of semi-heavy water ice in a protostellar envelope. This is the cloud of material surrounding a star in its embryonic stages.

The astronomers used the James Webb Space Telescope. Prior to its launch, the water deuteration ratio in star-forming regions could only be reliably measured in the gas phase, where chemical alteration occurs."Now, with the unprecedented sensitivity of Webb, we observe a beautifully clear semi-heavy water ice signature toward a protostar," says Katie Slavicinska, the Leiden University (Netherlands) PhD student who led the study.

The L1527 water deuteration ratio is very similar to that of some comets, as well as to the protoplanetary disk of a more evolved young star. This suggests that the water found in all of these objects has similar cold and ancient chemical origins.

"This finding adds to the mounting evidence that the bulk of water ice makes its journey largely unchanged from the earliest to the latest stages of star formation," says co-author Ewine van Dishoeck, a professor of astronomy at Leiden University who has spent much of her career tracing the journey of water through space.

Source:  Max Planck Institute for Extraterrestrial Physics/Press Releases

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Contact:

Ewine van Dishoeck
external scientific member
tel: +49 89 30000-3592
fax: +49 89 30000-3569
ewine@mpe.mpg.de

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Original publication

K. Slavicinska, Ł. Tychoniec, M. G. Navarro, E. F. van Dishoeck, et al.
HDO ice detected toward an isolated low-mass protostar with JWST 2025 ApJL L19

Source | DOI

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More Information

Detection of semi-heavy water ice around young sunlike star

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OJ 287: New image reveals sharply curved plasma jet at heart of mysterious galaxy

A new image of galaxy OJ 287 reveals for the first time the sharply curved, ribbon-like structure of the plasma jet emitted from its center. Credit: Dr Efthalia Traianou, Heidelberg University, IWR

For more than 150 years, the OJ 287 galaxy and its brightness variations five billion light years away has both puzzled and fascinated astronomers, because they suspect two supermassive black holes are merging in the core.

An international research team led by Dr. Efthalia Traianou of Heidelberg University recently succeeded in taking an image of the heart of the galaxy at a special level of detail. The groundbreaking image, taken with the aid of a space radio telescope, shows a heretofore unknown, heavily curved segment of the plasma jet spinning off the galaxy's center. The image provides new insights into the extreme conditions that prevail around supermassive black holes.

The research is published in the journal Astronomy & Astrophysics.

The core of the OJ 287 galaxy belongs to the class of blazars that exhibit high activity and striking luminosity. The driving forces behind these active galactic cores are black holes. They absorb matter from their surroundings and can fling it off in the form of giant plasma jets comprised of cosmic radiation, heat, heavy atoms, and magnetic fields.

"We have never before observed a structure in the OJ 287 galaxy at the level of detail seen in the new image," emphasizes Dr. Traianou, a postdoctoral researcher in the team of Dr. Roman Gold at the Interdisciplinary Center for Scientific Computing of Heidelberg University.

The image, which penetrates deep into the galaxy's center, reveals the sharply curved, ribbon-like structure of the jet; it also points to new insights into the composition and the behavior of the plasma jet. Some regions exceed temperatures of ten trillion degrees Kelvin—evidence of extreme energy and movement being released in close proximity to a black hole.

The researchers also observed the formation, spread, and collision of a new shock wave along the jet and attribute it to an energy in the trillion-electron volt range from an unusual gamma ray measurement taken in 2017.

The image in the radio range was taken with a ground-space radio interferometer consisting of a radio telescope in Earth's orbit—a ten-meter-long antenna of the RadioAstron mission on board the Spektr-R satellite—and a network of 27 ground observatories distributed across Earth.

In this way, the researchers were able to create a virtual space telescope with a diameter five times greater than the diameter of Earth; its high resolution stems from the distance of the individual radio observatories to one another. The image is based on a method of measurement that takes advantage of the wave nature of light and the associated overlapping waves.

The interferometric image underpins the assumption that a binary supermassive black hole is located inside galaxy OJ 287. It also provides important information on how the movements of such black holes influence the form and orientation of the plasma jets emitted.

"Its special properties make the galaxy an ideal candidate for further research into merging black holes and the associated gravitational waves," states Efthalia Traianou.

Institutions from Germany, Italy, Russia, Spain, South Korea, and the US all contributed to the research.

Source:  Phys.org/News

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More information: E. Traianou et al, Revealing a ribbon-like jet in OJ 287 with RadioAstron, Astronomy & Astrophysics (2025). DOI: 10.1051/0004-6361/202554929

Journal information: Astronomy & Astrophysics

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.Provided by Heidelberg University

by Marietta Fuhrmann-Koch, Heidelberg University

edited by Gaby Clark, reviewed by Robert Egan

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NASA’s Webb Traces Details of Complex Planetary Nebula

Image A: NGC 6072 (NIRCam Image)

NASA’s James Webb Space Telescope’s view of planetary nebula NGC 6072 in the near-infrared shows a complex scene of multiple outflows expanding out at different angles from a dying star at the center of the scene. In this image, the red areas represent cool molecular gas, for example, molecular hydrogen. Credit: NASA, ESA, CSA, STScI

Since their discovery in the late 1700s, astronomers have learned that planetary nebulae, or the expanding shell of glowing gas expelled by a low-intermediate mass star late in its life, can come in all shapes and sizes. Most planetary nebula present as circular, elliptical, or bi-polar, but some stray from the norm, as seen in new high-resolution images of planetary nebulae by NASA’s James Webb Space Telescope.

Webb’s newest look at planetary nebula NGC 6072 in the near- and mid-infrared shows what may appear as a very messy scene resembling splattered paint. However, the unusual, asymmetrical appearance hints at more complicated mechanisms underway, as the star central to the scene approaches the very final stages of its life and expels shells of material, losing up to 80 percent of its mass. Astronomers are using Webb to study planetary nebulae to learn more about the full life cycle of stars and how they impact their surrounding environments.

First, taking a look at the image from Webb’s NIRCam (Near-Infrared Camera), it’s readily apparent that this nebula is multi-polar. This means there are several different elliptical outflows jetting out either way from the center, one from 11 o’clock to 5 o’clock, another from 1 o’clock to 7 o’clock, and possibly a third from 12 o’clock to 6 o’clock. The outflows may compress material as they go, resulting in a disk seen perpendicular to it. Astronomers say this is evidence that there are likely at least two stars at the center of this scene. Specifically, a companion star is interacting with an aging star that had already begun to shed some of its outer layers of gas and dust. The central region of the planetary nebula glows from the hot stellar core, seen as a light blue hue in near-infrared light. The dark orange material, which is made up of gas and dust, follows pockets or open areas that appear dark blue. This clumpiness could be created when dense molecular clouds formed while being shielded from hot radiation from the central star. There could also be a time element at play. Over thousands of years, inner fast winds could be ploughing through the halo cast off from the main star when it first started to lose mass.

Image B: NGC 6072 (MIRI Image)

The mid-infrared view of planetary nebula NGC 6072 from NASA’s James Webb Space Telescope show expanding circular shells around the outflows from the dying central star. In this image, the blue represents cool molecular gas seen in red in the image from Webb’s NIRCam (Near-Infrared Camera) due to color mapping. NASA, ESA, CSA, STScI

The longer wavelengths captured by Webb’s MIRI (Mid-Infrared Instrument) are highlighting dust, revealing the star researchers suspect could be central to this scene. It appears as a small pinkish-whitish dot in this image.

Webb’s look in the mid-infrared wavelengths also reveals concentric rings expanding from the central region, the most obvious circling just past the edges of the lobes.

This may be additional evidence of a secondary star at the center of the scene hidden from our view. The secondary star, as it circles repeatedly around the original star, could have carved out rings of material in a bullseye pattern as the main star was expelling mass during an earlier stage of its life.

The rings may also hint at some kind of pulsation that resulted in gas or dust being expelled uniformly in all directions separated by say, thousands of years.

The red areas in NIRCam and blue areas in MIRI both trace cool molecular gas (likely molecular hydrogen) while central regions trace hot ionized gas.

As the star at the center of a planetary nebula cools and fades, the nebula will gradually dissipate into the interstellar medium — contributing enriched material that helps form new stars and planetary systems, now containing those heavier elements.

Webb’s imaging of NGC 6072 opens the door to studying how the planetary nebulae with more complex shapes contribute to this process.

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).

To learn more about Webb, visit: https://science.nasa.gov/webb

Source: NASA/mission/Webb

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Downloads:

View/Download all image products at all resolutions for this article from the Space Telescope Science Institute.

Media Contacts:

Laura Betz
laura.e.betz@nasa.gov
NASA’s Goddard Space Flight Center, Greenbelt, Md.

Hannah Braun
hbraun@stsci.edu
Space Telescope Science Institute, Baltimore, Md.

Related Information:

View more: Webb planetary nebula images

Learn more: about planetary nebula

Interactive: Explore the Helix Nebula planetary nebula

Watch: ViewSpace videos about planetary nebulas

More Webb News

More Webb Images

Webb Science Themes

Webb Mission Page

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Spiral Galaxy NGC 958

NGC 958
Low Res. ( 90 KB) / Mid. Res. ( 0.98 MB) / High Res. ( 7.7 MB)
Credit: NAOJ; Image provided by Masayuki Tanaka)

NGC 958 is a spiral galaxy located in the direction of Cetus. We observe the stellar disk at an angle, featuring two prominent grand-design spiral arms and dust lanes (dark lanes) across the disk. These dust lanes consist of interstellar dust that absorbs light, predominantly ultraviolet light from stars, and re-emits its energy as infrared emission. NGC 958 is classified as an ultra-luminous infrared galaxy (ULIRG) because of its exceptional brightness in infrared wavelengths, resulting from the absorption and re-emission processes of dust.

Surrounding NGC 958, you can see many other galaxies. However, it remains unclear whether these galaxies are nearby or unrelated foreground objects.

NGC 958 is a spiral galaxy located in the direction of Cetus. We observe the stellar disk at an angle, featuring two prominent grand-design spiral arms and dust lanes (dark lanes) across the disk. These dust lanes consist of interstellar dust that absorbs light, predominantly ultraviolet light from stars, and re-emits its energy as infrared emission. NGC 958 is classified as an ultra-luminous infrared galaxy (ULIRG) because of its exceptional brightness in infrared wavelengths, resulting from the absorption and re-emission processes of dust.

Distance from Earth: 180 million light-years
Instrument: Hyper S; uprime-Cam (HSC)

Source: Subaru Telescope/Press Release

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An artist's impression of a white dwarf polar system, consisting of a magnetic white dwarf accreting matter from its companion—for EF Eri, this is a star that has lost so much mass that it is now too small to undergo stellar fusion. Image credit: International Gemini Observatory/NOIRLab/NSF/AURA/University of Leicester (UK)/M. A. Garlick. Download Image

During the past week, NuSTAR observed the magnetic Cataclysmic Variable (mCV) EF Eridani, after it awoke from a nearly 30-year-long dormant period. mCVs are binary star systems consisting of a white dwarf and a companion star, where material from the companion is accreted onto the white dwarf. As this material falls, it reaches supersonic speeds, creating a shock wave that heats the material to over 100 million Kelvin and produces intense X-ray emission, detectable by NuSTAR. mCVs are of particular astrophysics interest since they are potential progenitors to Type Ia supernovae, a critical component of the cosmological distance ladder, and because they contribute significantly to the X-ray source population in the Galactic Center. This NuSTAR observation is coordinated with XRISM. NuSTAR’s broadband spectral sensitivity, combined with XRISM's precision spectroscopy, will provide scientists with unique insights into the accretion flow onto EF Eridani, revealing details of the heating, dynamics, and radiative processes that govern mCV systems.

Authors: Gabriel Bridges (PhD Student, Columbia University)

Source: NASA's Nuclear Spectroscopic Telescope Array (NuSTAR)

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A supernova-rich spiral

NGC 1309

A top-down view of a spiral galaxy, showing its brightly shining centre, its broad spiral arms and the faint halo around its disc, as well as distant galaxies and stars on a dark background. Large blue clouds of gas speckled with small stars and strands of dark dust swirl around the galaxy’s disc. A couple of the background galaxies are large enough that their own swirling spiral arms can be seen. Credit: ESA/Hubble & NASA, L. Galbany, S. Jha, K. Noll, A. Riess

Rich with detail, the spiral galaxy NGC 1309 shines in this NASA/ESA Hubble Space Telescope Picture of the Week. NGC 1309 is situated about 100 million light-years away in the constellation Eridanus.

This stunning Hubble image encompasses NGC 1309’s bluish stars, dark brown gas clouds and pearly white centre, as well as hundreds of distant background galaxies. Nearly every smudge, streak and blob of light in this image is an individual galaxy. The only exception to the extragalactic ensemble is a star, which can be identified near the top of the frame by its diffraction spikes. It is positively neighbourly, just a few thousand light-years away in the Milky Way galaxy.

Hubble has turned its attention toward NGC 1309 several times; previous Hubble images of this galaxy were released in 2006 and 2014. Much of NGC 1309’s scientific interest derives from two supernovae, SN 2002fk in 2002 and SN 2012Z in 2012. SN 2002fk was a perfect example of a Type Ia supernova, which happens when the core of a dead star (a white dwarf) explodes.

SN 2012Z, on the other hand, was a bit of a renegade. It was classified as a Type Iax supernova: while its spectrum resembled that of a Type Ia supernova, the explosion wasn’t as bright as expected. Hubble observations showed that in this case, the supernova did not destroy the white dwarf completely, leaving behind a ‘zombie star’ that shone even brighter than it did before the explosion. Hubble observations of NGC 1309 taken across several years also made this the first time the white dwarf progenitor of a supernova has been identified in images taken before the explosion.

Source: ESA/Hubble/potw

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Escaping the Dust Trap: Simulations of Dust Dynamics in Protoplanetary Disks

Radio images of protoplanetary disks where planets form around newly born stars.
Credit: ALMA (ESO/NAOJ/NRAO), S. Andrews et al.; NRAO/AUI/NSF, S. Dagnello; CC BY 4.0

Through detailed simulations of gas and dust, a recent study revealed that the behavior of dust within protoplanetary disks is a bit more complex than previously assumed.

Dust Traps in Protoplanetary Disks

As a planet forms within a protoplanetary disk — dust and gas orbiting a new star — tidal interactions between the budding body and the dusty material surrounding it can create pressure bumps where dust builds up. These dust traps appear as rings in observations of protoplanetary disks.

Dust traps are thought to play a critical role in the disk’s evolution and the early stages of planet formation. Dust traps may prevent solid material from migrating inward, starving the inner disk and impeding planet growth interior to the trap. These reservoirs may also serve as a chemical barrier, keeping volatile materials like water from moving to the inner regions of a disk.

While a perfect dust trap completely isolates material from the rest of the disk, recent observations and 2D simulations have shown that dust traps may be a bit more permeable — leaking smaller sized grains, mixing material, and changing the disk’s appearance. However, these results only account for two dimensions of the complex three-dimensional environment in which dust traps reside. Thus, 3D hydrodynamical simulations are necessary to provide more realistic details of dust dynamics within planet-hosting protoplanetary disks.

Z-axis averaged dust–gas density ratios (top) and dust–gas surface density ratios for the 3D simulations after 1,500 orbits. For the simulations with higher diffusion and lower planet mass, there is clear leaking of dust beyond the dust trap ring (edges marked with dotted red lines). Click to enlarge. Credit: Huang et al 2025

Dusty Simulations

In a recent study, Pinghui Huang (Chinese Academy of Sciences; University of Victoria) and collaborators performed multiple 2D and 3D numerical simulations of gas and dust within a protoplanetary disk with a forming planet. The simulations varied the mass of the planet and the level of turbulent diffusion — how well material and energy flow and mix within the gas. These variations allowed the authors to explore how dust traps behave within different types of systems.

The simulations showed that the embedded planet will perturb the gas and dust, producing density shocks that create gaps and, subsequently, pressure bumps where dust traps coalesce. From their analysis, the authors found that dust traps become leakier at higher levels of diffusion and when the embedded planet is lower in mass. Essentially, if the gas flows and mixes more efficiently, the perturbations of the planet are erased more quickly, and if the planet is sufficiently small, its ability to disrupt the disk is much weaker. Dust remains coupled to the gas, flowing through these weak traps without becoming stuck. Additionally, the 3D simulations show higher amounts of leakage compared to the 2D simulations, which the authors attributed to the asymmetric and complex vertical geometry of the disk.

Flux-trapping ratio (left) and mass-trapping ratio (right) as a function of time for the 2D (top) and 3D (bottom) simulations. The higher-mass planet in Model A causes more flux and mass-trapping than the lower-mass planets and more turbulent systems. Additionally, the 3D simulations show significantly lower flux and mass-trapping than the 2D simulations. Click to enlarge. Credit: Huang et al 2025

Implications and Comparison to Observations

What then are the consequences of leaky dust traps? In planet formation theory, dust traps determine the mass at which a planet creates a sufficient pressure bump that isolates small pebbles and dust exterior to its orbit. For perfect dust traps, this isolation of material from the planet and inner disk creates a clear chemical distinction between the inner and outer disk. However, as shown by the 3D simulations, dust traps are imperfect, allowing small particles to filter through; the authors suggest this may mean that the growing planet slows but does not stop the migration of solid materials in a disk.

Recent observations of protoplanetary disks reveal the presence of larger volatiles within the inner disk. Specifically, the disk PDS 70 shows water emission in its inner disk despite having two confirmed giant planets orbiting in the outer disk. Without leaky dust traps, volatiles like water would be trapped in the pressure bumps created by these planets. However, as the authors have shown, the complex reality of dust dynamics within protoplanetary disks allows heavier elements to leak through, enriching the inner disk. Further observations and detailed 3D simulations will allow astronomers to understand the extent of leaky dust traps and reveal the realistic conditions driving early planet formation.

By Lexi Gault

Citation

“Leaky Dust Traps in Planet-embedded Protoplanetary Disks,” Pinghui Huang et al 2025 ApJ 988 94.
doi:10.3847/1538-4357/addd1f

Source: American Astronomical Society/AAS-Nova

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NASA’s Chandra Finds Baby Exoplanet is Shrinking

X-ray: NASA/CXC/RIT/A. Varga et al.;
Illustration: NASA/CXC/SAO/M. Weiss;
Image Processing: NASA/CXC/SAO/N. Wolk

This transformation is happening as the host star unleashes a barrage of X-rays that is tearing the young planet’s atmosphere away at an enormous rate.

A baby planet is shrinking from the size of Jupiter with a thick atmosphere to a small, barren world, according to a new study from NASA’s Chandra X-ray Observatory.

The planet, named TOI 1227 b, is in an orbit around a red dwarf star about 330 light-years from Earth. TOI 1227 b orbits very close to its star — less than a fifth the distance that Mercury orbits the Sun. The new study shows this planet outside our solar system, or exoplanet, is a “baby” at a mere 8 million years old. By comparison, the Earth is about 5 billion years old, or nearly a thousand times older. That makes it the second youngest planet ever to be observed passing in front of its host star (also called a transit). Previously the planet had been estimated by others to be about 11 million years old.

A research team found that X-rays from its star are blasting TOI 1227 b and tearing away its atmosphere at such a rate that the planet will entirely lose it in about a billion years. At that point the planet will have lost a total mass equal to about two Earth masses, down from about 17 times the mass of Earth now.

“It’s almost unfathomable to imagine what is happening to this planet,” said Attila Varga, a Ph.D. student at the Rochester Institute of Technology (RIT) in New York, who led the study. “The planet’s atmosphere simply cannot withstand the high X-ray dose it’s receiving from its star.”

It is probably impossible for life to exist on TOI 1227 b, either now or in the future. The planet is too close to its star to fit into any definition of a ‘habitable zone,’ a term astronomers use to determine if planets around other stars could sustain liquid water on their surface.

The star that hosts TOI 1227 b, which is called TOI 1227, is only about a tenth the mass of the Sun and is much cooler and fainter in optical light. In X-rays, however, TOI 1227 is brighter than the Sun and is subjecting this planet, in its very close orbit, to a withering assault. The mass of TOI 1227 b, while not well understood, is likely similar to that of Neptune, but its diameter is three times larger than Neptune’s (making it similar in size to Jupiter).

“A crucial part of understanding planets outside our solar system is to account for high-energy radiation like X-rays that they’re receiving,” said co-author Joel Kastner, also of RIT. “We think this planet is puffed up, or inflated, in large part as a result of the ongoing assault of X-rays from the star.”

The team used new Chandra data to measure the amount of X-rays from the star that are striking the planet. Using computer models of the effects of these X-rays, they concluded the X-rays will have a transformative effect, rapidly stripping away the planet’s atmosphere. They estimate that the planet is losing a mass equivalent to a full Earth’s atmosphere about every 200 years.

“The future for this baby planet doesn’t look great,” said co-author Alexander Binks of the Eberhard Karls University of Tübingen in Germany. “From here, TOI 1227 b may shrink to about a tenth of its current size and will lose more than 10 percent of its weight.”

The researchers used different sets of data to estimate the age of TOI 1227 b. One method exploits measurements of how TOI 1227 b’s host star moves through space compared to nearby populations of stars with known ages. A second method compared the brightness and surface temperature of the star with theoretical models of evolving stars.

Of all the exoplanets astronomers have found with ages less than 50 million years, TOI 1227 b stands out for having the longest year and the host planet with the lowest mass.

A paper describing these results has been accepted publication in The Astrophysical Journal, and a preprint is available here.

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.

Source: NASA/NASA’s Chandra X-ray Observatory

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Read more from NASA’s Chandra X-ray Observatory:

Learn more about the Chandra X-ray Observatory and its mission here:https://www.nasa.gov/chandra-https://chandra.si.edu

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Visual Description

This release features an artist’s illustration of a Jupiter-sized planet closely orbiting a faint red star. An inset image, showing the star in X-ray light from Chandra, is superimposed on top of the illustration at our upper left corner.

At our upper right, the red star is illustrated as a ball made of intense fire. The planet, slightly smaller than the star, is shown at our lower left. Powerful X-rays from the star are tearing away the atmosphere of the planet, causing wisps of material to flow away from the planet’s surface in the opposite direction from the star. This gives the planet a slight resemblance to a comet, complete with a tail.

X-ray data from Chandra, presented in the inset image, shows the star as a small purple orb on a black background. Astronomers used the Chandra data to measure the amount of X-rays striking the planet from the star. They estimate that the planet is losing a mass equivalent to a full Earth’s atmosphere about every 200 years, causing it to ultimately shrink from the size of Jupiter down to a small, barren world.

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News Media Contact:

Megan Watzke
Chandra X-ray Center
Cambridge, Mass.
617-496-7998
mwatzke@cfa.harvard.edu

Corinne Beckinger
Marshall Space Flight Center, Huntsville, Alabama
256-544-0034
corinne.m.beckinger@nasa.gov

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