Signs of a Supermassive Black Hole Merger in NGC 4486B

This Hubble Space Telescope image shows two galaxies in the process of merging. When two galaxies merge, their respective supermassive black holes can form a binary that eventually merges as well. Credit: ESA/Hubble & NASA, W. Keel, SDSS; CC BY 4.0

The galaxy NGC 4486B appears calm and collected, but its center may have been roiled by a recent merger of supermassive black holes. New modeling explores the stellar dynamics that support this hypothesis.

Kinematic maps of NGC 4486B showing the locations of the two peaks of its double nucleus.
Adapted from Tahmasebzadeh et al 2026

Strange Center

Astronomers have known for 30 years that NGC 4486B, a compact elliptical galaxy near the center of the Virgo cluster, has a double nucleus. More recently, JWST observations revealed that the galaxy houses a black hole of 360 million solar masses, which is unusually large compared to the galaxy’s stellar mass of 9 billion solar masses. The two nuclei are roughly 40 light-years from the apparent center of the galaxy, and the black hole also appears to be offset from the galactic center by 20 light-years.

Now, a team led by Behzad Tahmasebzadeh (University of Michigan; Villanova University) has investigated the possibility that NGC 4486B’s double nucleus and off-center black hole can be traced to the aftermath of a supermassive black hole merger.

Estimated black hole kick magnitude as a function of the initial mass ratio of the black hole binary.
Tahmasebzadeh et al. 2026

Simulating Kinematics

In this scenario, the black hole is displaced from the galaxy’s center because of a “kick” it received when it underwent a merger. The double nucleus is a sign of an eccentric nuclear disk: a central disk of stars on aligned elliptical orbits created when merging supermassive black holes disturb an initially orderly disk of stars.

Tahmasebzadeh and collaborators performed dynamical modeling to test this hypothesis and understand what types of stellar orbits would be necessary to reproduce the kinematic signature of NGC 4486B’s center seen with JWST. The simulation results called for a blend of prograde and retrograde stellar orbits that closely resembled what is expected for an eccentric nuclear disk. From the properties of the simulated stellar disk, the team estimated that the mass ratio of the merging black holes was >0.15.

To explore this scenario further, the team carried out N-body simulations of the post-merger black hole’s behavior. These simulations showed that after being booted from the galactic center by the post-merger kick, the black hole returns to the center quickly — within 10–80 million years, depending on the kick strength. Because NGC 4486B’s supermassive black hole is notably off center, this suggests that the merger occurred recently.

Galaxy Merger Versus Black Hole Merger

Tahmasebzadeh’s team tested two other theories that could explain the appearance of NGC 4486B’s nucleus: dynamical buoyancy and a pre-merger supermassive black hole binary. Neither of these scenarios could reproduce the offsets seen in the center of the galaxy.

The team noted that NGC 4486B appears to be in equilibrium, with no sign of a recent merger that could have plunked a second supermassive black hole into the galaxy. How can this fact be reconciled with the evidence for a recent black hole merger? Turning again to simulations, the team found that if the black hole binary’s orbit was aligned with the galaxy’s rotation, the binary could have become trapped in a resonance that greatly delayed the merger of the black holes. This makes it possible that NGC 4486B underwent a galaxy merger in the distant past, but its central black hole merged only recently, leaving signs of a long-ago merger that has otherwise faded from view.

By Kerry Hensley

Citation

“JWST Observations of the Double Nucleus in NGC 4486B: Possible Evidence for a Recent Binary SMBH Merger and Recoil,” Behzad Tahmasebzadeh et al 2026 ApJL 1001 L14. doi:10.3847/2041-8213/ae52ef

Source: American Astronomical Society/AAS-Nova

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JWST Spies Once-hidden Treasures in the W51 Starbirth Crèche

A mid-infrared view of M51 provided by the James Webb Space Telescope's MIRI instrument. Swirls of interstellar gas are being illuminated by massive young newborn stars.Credit: NASA, ESA, CSA, Yoo & Ginsburg (UF). Image processing: A Pagan (STScI)

Star formation is a dramatic and complex process that erupts throughout the Universe. Yet, a lot of that action gets hidden by clouds of gas and dust. That's where observatories such as the James Webb Telescope JWST and the Atacama Large Millimeter Array (ALMA) come in handy. They use infrared light and radio waves respectively, to pierce the veil surrounding the process of starbirth.

A team led by University of Florida doctoral candidate Taehwa Yoo recently used to JWST to make observations of the giant Milky Way starbirth region Westerhout 51 (W51). It lies about 17,000 light-years away from Earth in the direction of the constellation Sagittarius. The images and data they collected revealed many fine details of the star-formation activity going on there. “With optical and ground-based infrared telescopes, we can’t see through the dust to see the young stars,” said Adam Ginsburg, Ph.D., a professor of astronomy at UF. “Now we can.”

An overview of W51A region. The composite image is produced by combining NIRCam F360M (blue), F410M (green), and MIRI F560W (red) on JWST. The north and east directions in ICRS coordinates are marked as arrows at the upper left corner. Courtesy Yoo, et al.

Despite the impressive images and data, some aspects of star birth remain hidden away behind clouds too dense even for JWST to pierce. The team compared their JWST images to observations of the same region made by the ALMA, and found that only a fraction of stars are detectable by both telescopes. The observations that JWST did make, however, showed a lot of detail in the structures it could see. And that provides astronomers with new insights into the starbirth process. "Because of James Webb, we can see those hidden, young massive stars forming in this star-forming region," Yoo said. "By looking at them, we can study their formation mechanisms."

Cutout images of specific regions in W51. (a) A dust filament around W51-E. (b) W51-IRS2 protocluster. (c) Cometary objects around W51-IRS2 (these are globules of dust that look like comets, sculpted by radiation from nearby stars). (d) W51-E protocluster. (e) A bar at the edge of IRS1 H II region. (An HII region is a cloud of mostly hydrogen gas from which stars can form.) (f) W51 IRS1 H II region shell structure. (g) W51b1 H II region. (h) W51b2 H II region and YSOs. (i) W51e7 H II region. (j) W51c1 H II region. (k) and (l) Newly discovered H II regions. Courtesy Yoo, et al.

Digging Into W51's Starbirth Activity

W51 is divided into several regions of enhanced star formation. As part of the observations, JWST zeroed in on the W51A region, the youngest starbirth crèche in the area. Multiple clouds of ionized gas and warm dust exist there, with some of the dust arranged in filaments. The science team also spotted a good example of a cavity around one of the newborn stars, which indicates that the star is "eating away" at its birthplace. They also studied giant gas bubbles of gas, dark dust filaments (which are likely still-hidden crèches), cometary objects, and protostellar jets streaming away from protostellar objects. Each of these are part of the starbirth process.

The team focused on the massive protoclusters called W51-E and W51-IRS2, using the Near Infrared Camera (NIRCAM) and the Mid-infrared Instrument (MIRI). Most of the stars they were able to observe are still accreting material and hadn't yet reached their full masses. Some have only formed in the past million years or so.

Yoo's group estimates there are about 10,000 solar masses of stars in W51A. Many are very young, massive stars, and not a lot is known about their earliest infancy, which is what fascinates astronomers today. In some areas, those remain hidden by too-thick clouds of gas and dust. Luckily, W51A has a lot to offer based on previous studies made by the Atacama Large Millimeter/submillimeter Array (ALMA). That radio array in Chile detected over 200 compact sources referred to as “PPOs (Pre/Protostellar Objects)” in the region. These are places where stars are actively forming or will start to form in the relatively near future. Astronomers want to know what kickstarts the process of star formation in regions like these, and what stages occur as massive young stars begin to form.

Combined observations from JWST and ALMA show the location of protocluster regions where multiple stars are forming. The locations of the matching sources are marked in the upper panel with the background image of F162M, F210M, and F480M filters on JWST. In the lower panels, W51-E and W51-IRS2 protocluster regions are zoomed in with the background image of the JWST NIRCam filters and ALMA 1.3 mm image combined. Courtesy Yoo, et al.

Starbirth Stages

In a general sense, astronomers know the overall process of starbirth: clouds of gas and dust condense and form hot cores called "young stellar objects." These are where the future star will be born. After a period of accretion, the star reaches a point where it begins fusing hydrogen to helium in its core. That's the point where the star is born. Before that, the star begins as that hot core, and also blows material away from itself via a superheated jet. High-mass stars born like this obviously affect their environment, especially in their birth crèches. They interact with neighboring clouds of gas, which affects the formation of sibling stars in the same region. The radiation from those high-mass stars can even go so far as to rip apart the clouds of gas. That chokes off the available material for new stars to form. From the JWST images and data, it's clear that each of those steps is in process in the W51A cloud.

In a recent paper in the Astrophysical Journal (noted below), Yoo and the team point out that several hot cores with rich chemistry associated with massive protostars exist in W51A. These are very likely sites of maser emissions from several varieties of molecules in the gas clouds crèches, including OH (hydroxide), CH3OH (methanol), SiO (silicon monoxide), NH3 (ammonia), and CS (carbon monosulfide). The presence of these masers acts as a tracer for dense molecular clouds where stars are expected to form (if they aren't doing so already).

In addition to the hot cores that indicate the very early stellar birth process, the team also observed at least one "knot" of emission from a protostellar object. It indicates ionized iron and hydrogen within the cloud. They think it's from a jet streaming from a hot young star that's heating up and affecting the nearby interstellar medium.

This latest look at W51 with JWST gives astronomers a much better idea of what different stages of starbirth look like, stages that are normally hidden from optical observations. The quality of the JWST data revealed more information and showed new structures in the area that astronomers can now use to more fully explain the process of starbirth. “They are not the first photos of this region, but they are the best,” said Ginsburg. “They’re so much better that they essentially are brand new photos. Every time we look at these images, we learn something new and unexpected."

By Carolyn Collins Petersen - April 06, 2026 01:04 AM UTC | Stars

Source: Universe Today

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For More Information

Researchers Use JWST to Reveal Hidden Details of W51 Star Formation

A JWST NIRCam/MIRI view of the W51A high-mass star-forming region

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Carolyn Collins Petersen

Carolyn Collins Petersen is a long-time science writer and former astronomy researcher. She writes about astronomy and space exploration and has written 8 books, countless articles, more than 60 documentaries for planetarium star theaters, and exhibits for Griffith Observatory, NASA/JPL, the California Academy of Sciences, the Shanghai Astronomical Museum, and the Lowell Observatory Dark Sky Planetarium. She is CEO of Loch Ness Productions. You can email Carolyn here.

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NuSTAR Investigates a Pulsar's Unusual Behavior

A hand-drawn artist's impression of the current state of the Her X-1 system, showing gas being pulled from the companion star onto the accretion disk surrounding the neutron star. Its magnetic field lines and rotation axis are marked in black and misaligned with each other, which is what causes pulsations to be seen. Image credit: R. Staubert. Download Image

During the last two months, NuSTAR has responded to the unusual behavior of Hercules X-1, one the most enigmatic binary X-ray pulsars, through a series of short observations. High-energy, all-sky monitoring instruments, including NASA's Swift and JAXA's MAXI missions, had observed the X-ray flux of Her X-1 decrease to a very low level, indicating the source had entered a so-called "anomalous low" state. Such a behavior has been observed only a few times previously, with durations ranging from 70 to 602 days. In response, a small group of Her X-1 enthusiasts succeeded in organizing a coordinated observing campaign, triggering proposed Target of Opportunity observations and obtaining Director's Discretionary Time using several satellites, including NASA's NuSTAR, JAXA's XRISM, and ESA's XMM-Newton observatories. The goal is to understand in detail what is physically happening in Her X-1, and initial analysis of the data indicates that the X-ray source has not actually turned off. The accretion of material from the companion star onto the highly magnetized neutron star continues, but the low X-ray energy radiation is now substantially absorbed by the accretion disk itself, not just at certain phases of the generally observed 35-day modulation, but continuously. It may be possible that precessing accretion disk has either changed its inclination with respect to the binary orbital plane, or has swelled up to a substantially larger thickness. Less certain is whether the rotation of the neutron star itself precesses freely with a period very close to that of the accretion disk, though analysis of the NuSTAR data shows that the neutron star pulsation period of 1.24 seconds appears normal. It is possible that the neutron star and accretion precessional movements are generally locked to each other by physical interactions, which might change at times or even temporarily break down. Monitoring of Her X-1 will continue into the next month.

Author: Ruediger Staubert (Professor of Astrophysics, University of Tuebingen, Germany)

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

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Rubin Observatory Early Data from NSF–DOE Vera C. Rubin Observatory Reveals Over 11,000 New Asteroids

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3D rendering of asteroids discovered by NSF–DOE Rubin Observatory

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Asteroids discovered by NSF–DOE Rubin Observatory infographic

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3D rendering of trans-Neptunian objects discovered by NSF–DOE Rubin Observatory

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Distribution of new asteroids discovered by NSF–DOE Rubin Observatory

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3D model of asteroids discovered by NSF–DOE Rubin Observatory (polar view)

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Videos


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3D animation of asteroids discovered by NSF–DOE Rubin Observatory (close)


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3D animation of asteroids discovered by NSF–DOE Rubin Observatory

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Rubin’s largest asteroid haul yet, gathered before the Legacy Survey of Space and Time even begins, is just the “tip of the iceberg”

Scientists at NSF–DOE Vera C. Rubin Observatory, jointly funded by the U.S. National Science Foundation and the U.S. Department of Energy's Office of Science, have submitted an unprecedented set of asteroid detections to the IAU Minor Planet Center, including hundreds of distant worlds beyond Neptune and 33 previously unknown near-Earth asteroids.

Using preliminary data from NSF–DOE Vera C. Rubin Observatory, scientists have discovered over 11,000 new asteroids [1]. The data were confirmed by the International Astronomical Union’s Minor Planet Center (MPC), making this the largest single batch of asteroid discoveries submitted in the past year. The discoveries were made using data from Rubin’s early optimization surveys and offer a powerful preview of the observatory’s transformative impact on Solar System science.

Rubin Observatory is a joint program of NSF NOIRLab and DOE’s SLAC National Accelerator Laboratory, who cooperatively operate Rubin. NOIRLab is managed by the Association of Universities for Research in Astronomy (AURA).

The submission to MPC comprises approximately one million observations, taken over the span of a month and a half, of over 11,000 new asteroids and more than 80,000 already known asteroids, including some that had previously been observed but were later “lost” because their orbits were too uncertain to predict their future locations. You can interact with all of Rubin’s asteroid discoveries in the Rubin Orbitviewer, which uses real data to provide an intuitive way to explore the structure of our cosmic backyard in three dimensions and in real time. Also, visit the Rubin Asteroid Discoveries Dashboard to learn about the new objects Rubin has uncovered.

“This first large submission after Rubin First Look is just the tip of the iceberg and shows that the observatory is ready,” says Mario Juric, faculty at the University of Washington and Rubin Solar System Lead Scientist. “What used to take years or decades to discover, Rubin will unearth in months. We are beginning to deliver on Rubin’s promise to fundamentally reshape our inventory of the Solar System and open the door to discoveries we haven’t yet imagined.”

Among the newly identified objects are 33 previously unknown near-Earth objects (NEOs), which are small asteroids and comets whose closest approach to the Sun is less than 1.3 times the distance between Earth and the Sun. None of the newly discovered NEOs pose a threat to Earth, and the largest is about 500 meters wide. Objects larger than 140 meters are closely tracked as they could cause significant regional damage if they impact, yet scientists estimate that only about 40% of these mid-sized NEOs have been identified so far.

Once operating fully in survey mode, Rubin is expected to reveal an additional nearly 90,000 new NEOs, some of which may be potentially hazardous, and to nearly double the number of known NEOs larger than 140 meters to around 70%. By enabling early detection and continuous monitoring of these objects, Rubin will be a powerful tool for planetary defense.

The dataset also contains roughly 380 trans-Neptunian objects (TNOs) — icy bodies orbiting beyond Neptune. Two of the newly discovered TNOs — provisionally named 2025 LS₂ and 2025 MX₃₄₈ — have been found to be on extremely large and elongated, or stretched out, orbits. At their most distant points, these two objects reach roughly 1000 times farther away from the Sun than the Earth is, placing them among the 30 most distant minor planets known.

This animation shows the inner Solar System populated with known asteroids in dark blue and asteroids discovered by Rubin in light teal. Read morehere. Credit: NSF–DOE Vera C. Rubin Observatory/NOIRLab/SLAC/AURA/R. Proctor. Star map: NASA/Goddard Space Flight Center Scientific Visualization Studio. Gaia DR2: ESA/Gaia/DPAC. Image Processing: M. Zamani (NSF NOIRLab)

The discoveries were enabled by Rubin Observatory’s unique combination of a large mirror, the world’s most powerful astronomical digital camera, and highly sophisticated, software-driven pipelines designed to detect faint, fast-moving objects against a crowded sky. Rubin can survey the southern sky at roughly six times the sensitivity of most current asteroid searches, allowing it to detect smaller and more distant objects than ever before. These capabilities will allow Rubin to build the most detailed census of our Solar System ever, and all of the discoveries will help scientists work out the story of the Solar System’s history.

“Rubin’s unique observing cadence required a whole new software architecture for asteroid discovery,” says Ari Heinze, University of Washington, who, together with Jacob Kurlander, a graduate student at the University of Washington, built the software that detected them. “We built it, and it works. Even with just early, engineering-quality data, Rubin discovered 11,000 asteroids and measured more precise orbits for tens of thousands more. It seems pretty clear this observatory will revolutionize our knowledge of the asteroid belt.”

Particularly striking is the rapid growth of the TNO population. The 380 candidates discovered by Rubin in less than two months add to the 5000 discovered over the past three decades. As with less distant asteroids, finding the TNOs depended critically on developing new sophisticated algorithms.

“Searching for a TNO is like searching for a needle in a field of haystacks — out of millions of flickering sources in the sky, teaching a computer to sift through billions of combinations and identify those that are likely to be distant worlds in our Solar System required novel algorithmic approaches,” says Matthew Holman, a Senior Astrophysicist at the Center for Astrophysics | Harvard & Smithsonian and former Director of the Minor Planet Center, who spearheaded the work on the TNO discovery pipeline.

“Objects like these offer a tantalizing probe of the Solar System’s outermost reaches, from telling us how the planets moved early on in the Solar System’s history, to whether a hitherto undiscovered 9th large planet may still be out there,” says Kevin Napier, a research scientist at the Harvard-Smithsonian Center for Astrophysics who, with Holman, developed the algorithms to detect distant Solar System objects with Rubin data.

The MPC's verification of this large group of discoveries enables the entire global community to access the data, refine orbits, and begin analysis immediately. And these ~11,000 asteroids are just the start. Once the decade-long Legacy Survey of Space and Time (LSST) begins later this year, scientists expect Rubin to discover this many asteroids every two to three nights during the early years of the survey. This will ultimately triple the number of known asteroids and increase the number of known TNOs by nearly an order of magnitude.

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

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Notes

[1] The new asteroid discoveries reported here are in addition to the ~1500 asteroid discoveries announced as part of Rubin First Look. When originally announced, 2104 of the asteroids were registered as new. Since then, 600 of the asteroids have been connected to earlier observations by the IAU Minor Planet Center, and hence reclassified as “recovered asteroids” and not discoveries.

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More information

This research is available at the Rubin Asteroid Discoveries Dashboard.

The team is composed (in alphabetical order) of P. H. Bernardinelli (UW and USP, Brazil), S. Eggl (UIUC), A. Heinze (UW), M. Holman (CfA), M. Juric (UW), J. Kurlander (UW), J. Moeyens (B612 Asteroid Institute), K. Napier (CfA), and E. Nourbakhsh (Princeton).

NSF–DOE Vera C. Rubin Observatory, funded by the U.S. National Science Foundation and the U.S. Department of Energy’s Office of Science, is a groundbreaking new astronomy and astrophysics observatory on Cerro Pachón in Chile. It is named after astronomer Vera Rubin, who provided the first convincing evidence for the existence of dark matter. Using the largest camera ever built, Rubin will repeatedly scan the sky for 10 years to create an ultra-wide, ultra-high-definition, time-lapse record of our Universe.

NSF–DOE Vera C. Rubin Observatory is a joint initiative of the U.S. National Science Foundation (NSF) and the U.S. Department of Energy’s Office of Science (DOE/SC). Its primary mission is to carry out the Legacy Survey of Space and Time, providing an unprecedented data set for scientific research supported by both agencies. Rubin is operated jointly by NSF NOIRLab and SLAC National Accelerator Laboratory. NSF NOIRLab is managed by the Association of Universities for Research in Astronomy (AURA) and SLAC is operated by Stanford University for the DOE. France provides key support to the construction and operations of Rubin Observatory through contributions from CNRS/IN2P3. Rubin Observatory is privileged to conduct research in Chile and gratefully acknowledges additional contributions from more than 40 international organizations and teams.

The U.S. National Science Foundation (NSF) is an independent federal agency created by Congress in 1950 to promote the progress of science. NSF supports basic research and people to create knowledge that transforms the future

The DOE’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time.

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

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

SLAC National Accelerator Laboratory explores how the Universe works at the biggest, smallest and fastest scales and invents powerful tools used by researchers around the globe. As world leaders in ultrafast science and bold explorers of the physics of the Universe, we forge new ground in understanding our origins and building a healthier and more sustainable future. Our discovery and innovation help develop new materials and chemical processes and open unprecedented views of the cosmos and life’s most delicate machinery. Building on more than 60 years of visionary research, we help shape the future by advancing areas such as quantum technology, scientific computing and the development of next-generation accelerators. SLAC is operated by Stanford University for the U.S. Department of Energy’s Office of Science.

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Links

• Check out Rubin’s current Solar System census in the Rubin Orbitviewer
• Explore the Rubin Asteroid Discoveries Dashboard
• Vera C. Rubin Observatory website
• Vera C. Rubin Observatory image gallery
• More Rubin images
• More Rubin videos
• Check out other NOIRLab Science Releases

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Contacts:

Mario Juric
Rubin Solar System Lead Scientist
University of Washington
Email: mjuric@uw.edu

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

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X-ray panorama of the “Manatee Nebula” by SRG/eROSITA

Figure 1 shows a composite X-ray image of the radio nebula W50 taken with the eROSITA telescope. The surface brightness of the X-ray emission is colour-coded in the 0.5–1 keV (red), 1–2 keV (green), and 2–4 keV (blue) energy bands. The white arrows depict the projection of the SS433 jets' precession cone extrapolated to distances of more than 100 pc. The hard and soft X-ray diffuse emission can be convincingly split into two components: softer filamentary emission (red-yellow) and harder (green-blue) emission from EXJs. Additionally, there are numerous nearby compact sources, such as active stars and accreting white dwarfs, as well as distant compact sources, mostly AGN. For distant sources, absorption by Milky Way gas suppresses emission below 1 or 2 keV, giving them a blue colour. © MPA; eROSITA/SRG

Figure 2 shows a schematic summary of the W50 nebula superimposed on a composite X-ray (red and green) and radio (VLA at 1.4 GHz, blue) image. Radio emission most likely arises at the outer, shell-like boundary of the nebula, while soft X-ray emission (0.3–0.9 keV) traces shock-heated interstellar medium (ISM) gas behind it, filling almost the entire interior of the nebula. The harder X-ray emission (0.9–2.7 keV in this case) is of a non-thermal (synchrotron) nature and may be produced by ultrarelativistic electrons that are accelerated at the shocks in the axial outflows from the system. The central part of the nebula, within 25 pc of SS433 (dashed circle), is likely to be of very low density and could be a wind-blown cavity created by an almost spherically symmetric outflow with a kinetic luminosity close to the Eddington limit. © MPA; eROSITA/SRG

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Rare or unusual astrophysical objects are used to test the limits of theoretical models because of their extreme properties. The bright X-ray source SS433 in our galaxy undoubtedly belongs to this category. Initially identified as an Hα emitter, it was later recognised as a black hole in a binary system. Since then, SS433, which emits strongly in the radio and X-ray bands, has been targeted by almost every space- and ground-based observatory, leading to a flurry of discoveries.  In contrast, the surrounding huge W50 nebula, spanning more than two degrees, is much fainter and difficult to study. The complete radio image earned W50 the nickname 'Manatee Nebula', while X-ray maps were mostly patches from different observatories or lacked spatial or energy resolution. This shortcoming has finally been overcome by the recently published SRG/eROSITA map of W50 in multiple X-ray colours, which reveals a beautiful blend of thermal and non-thermal processes within an elongated cocoon.

At the core of the W50 nebula lies a compact source (most likely a stellar-mass black hole) that accretes matter from a companion star at an astonishingly high rate — thousands of times greater than the amount the black hole can digest. This limiting rate (known as the Eddington accretion rate) arises due to the pressure exerted by the radiation produced by the infalling gas. This configuration has an immediate impact on the observational appearance of the compact source and its large-scale environment. The key prediction of the accretion theory is that most of the gas supplied to the black hole will be expelled from the system, depositing a large amount of energy into the ambient medium in the process (see Highlight September 2024).

The W50 nebula is well known in radio astronomy for its croissant-like shape. Mapping this large nebula in X-rays used to be problematic due to the limited field of view of space telescopes. Additionally, strong and inhomogeneous absorption by gas and dust occurs in the direction of W50, which is located just two degrees away from the Galactic Plane. These problems can be resolved by using a telescope with a large field of view and high sensitivity to diffuse emission — the very characteristics of the eROSITA telescope on board the SRG observatory.

The full-size X-ray map of the W50 nebula is shown in Fig. 1. The central bright spot is the black hole that powers the entire nebula. It appears extended because it is much brighter than the nebula emission, causing the central part of the image to become saturated.

The 'X-ray colours' in this figure serve the same role as red, green, and blue colours in visible light. Specifically, red corresponds to X-ray photons with a longer wavelength, while green and blue correspond to progressively shorter wavelengths. Remarkably, this simple approach immediately reveals the nature of the X-ray emission: red and yellow colours dominate where thermal plasma with a temperature of 2–10 million degrees is present. Conversely, in the bluer regions, non-thermal emission from relativistic particles dominates.

The nebula is clearly asymmetric, most likely due to a gradient in the ambient gas density surrounding it. The most remarkable feature is the so-called 'Extended X-ray Jets' (EXJs), which have sharp inner edges located around 25 parsecs from the central black hole SS433. Their spectra do not have the emission lines characteristic of thermal plasma. Rather, they must be due to the emission of relativistic particles accelerated by shocks powered by SS433’s outflows. These structures have recently been detected at TeV energies; each TeV photon carries a billion times more energy than a soft X-ray photon at keV energies.

These new X-ray data support the idea that the energy flow from SS433 evolves through three distinct stages:

1) an invisible 'dark' flow of energy between the black hole and the EXJs, presumably carried by a cold wind from the binary system;

2) a 'non-thermal' flow of energy over some 30 pc in the form of EXJs; and

3) a thermal flow (i.e., shock-heated interstellar medium (ISM)) that envelops the EXJs.

The thermal part of the W50 X-ray emission can be reasonably well described by a shock-heated plasma that has not yet reached temperature and ionisation equilibrium. Such emission is typical of middle-aged or old supernova remnants (SNRs). The outer radio boundary of the nebula also resembles SNR shocks (see Fig. 2).

In contrast, the 'extended X-ray jets' are the most remarkable features of this system on tens-of-pc scales. Their sharp inner edges plausibly correspond to extreme shocks that accelerate particles and power the X-ray (synchrotron) and TeV emission, which is 9–10 orders of magnitude more energetic. The W50/SS433 system clearly illustrates the important role that hyper-Eddington accretors might play in the energetics of the interstellar medium in galaxies at different redshifts, as well as in the production of ultra-high-energy particles.

Source: Max Planck Institute for Astrophysics/Research Highlights

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Authors:

Rashid Sunyaev
Emeritus Director
Tel: 2244
Email: rsunyaev@mpa-garching.mpg.de

Eugene Churazov
Scientific Staff
Tel: 2219
Email: echurazov@mpa-garching.mpg.de

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Original publication

Sunyaev R., Khabibullin I., Churazov E., Gilfanov M., Medvedev P., Sazonov S.
X-ray panorama of the SS433/W50 complex by SRG/eROSITA
A&A, in press

DOI

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New Leibniz ScienceCampus SCALES advances innovative modelling approaches in astrophysics and climate physics

>Overview of the physical systems studied within the Leibniz ScienceCampus SCALES focusing on astrophysical topics and topics related to climate physics and Earth system modelling.

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March 25, 2026 // With the approval of the new Leibniz ScienceCampus “Multiscale Challenges: from Astrophysics to Climate Models,” the Leibniz Association is launching an ambitious initiative to bring together leading expertise from astrophysics, climate science, and applied mathematics. At the same time, the funding marks a milestone for Brandenburg: emerging from the successful initiative of the Leibniz Institute for Astrophysics Potsdam (AIP), this establishes the first ever Leibniz ScienceCampus in the state.

The Senate of the Leibniz Association approved funding for a new Leibniz ScienceCampus, “Multiscale Challenges: from Astrophysics to Climate Models” on March 24, 2026. The Campus will be jointly funded by the participating Leibniz institutes, the Leibniz Association, the University of Potsdam, and the state of Brandenburg, with a total budget of 4.12 million euros.

Under the leadership of the AIP, the Campus is being established in close collaboration with the University of Potsdam as well as the participating Leibniz institutes — the Potsdam Institute for Climate Impact Research and the Weierstrass Institute for Applied Analysis and Stochastics. Additional partners include the Deutsche Elektronen-Synchrotron DESY, the Max Planck Institute for Gravitational Physics, and the German Center for Astrophysics. The initiative will be coordinated by Prof. Dr. Christoph Pfrommer (AIP), who serves as a spokesman together with Prof. Dr. Tim Dietrich from University of Potsdam.

Brandenburg's Minister of Science, Dr. Manja Schüle, offers her congratulations: “A milestone for Brandenburg’s scientific community: we are establishing our first Leibniz ScienceCampus. This is a substantive win, as the interdisciplinary research approach integrates state-of-the-art simulation techniques across both small and large scales. This enables researchers to better understand and predict complex phenomena – from galaxy formation to climate change – by bringing together expertise in astrophysics, climate science, and applied mathematics. It’s also a structural win for our state, as the AIP, the University of Potsdam, and the Potsdam Institute for Climate Impact Research will be able to pool their expertise. Strengthening collaboration will be a central pillar of our forthcoming research strategy – and the Leibniz ScienceCampus ‘Multiscale Challenges: from Astrophysics to Climate Models’ is already anticipating this direction and putting it into practice. This is what a forward-looking research ecosystem ‘made in Brandenburg’ looks like.”

“Many of the most pressing scientific questions arise from the interplay of processes operating across vastly different spatial and temporal scales. Whether in galaxies or here on Earth, small-scale processes shape large-scale behavior. The ScienceCampus brings together expertise from astrophysics and Earth system science to develop new computational and data-driven approaches that model these interactions more consistently and precisely across all scales, ultimately enabling better predictions,” says Prof. Dr. Christoph Pfrommer.

At its core are next-generation simulation techniques, hybrid modelling strategies, and the use of artificial intelligence, particularly neural networks that learn physical laws. The goal is to significantly improve the representation of subscale processes in both astrophysical and climate models. In climate research, this will enable more precise projections and more robust strategies for the mitigation of and adaptation to climate change. In astrophysics, the Campus will advance our understanding of key phenomena such as galaxy formation, neutron star mergers, and exoplanet atmospheres, thereby bridging the gap to climate physics.

“The new ScienceCampus provides a unique platform to integrate methods and perspectives from different disciplines and to advance truly interdisciplinary research. By combining observational data, theoretical modelling, and state-of-the-art computational techniques, we can generate new insights into complex systems. This collaborative approach will not only strengthen the Potsdam–Berlin research region but also enhance international visibility and contribute to tackling urgent societal issues like climate change,” says Prof. Dr. Tim Dietrich.

Leibniz ScienceCampuses promote strategic, thematically focused collaboration between Leibniz institutes, universities, and external partners within a regional context. They strengthen interdisciplinarity, pool scientific excellence, and create internationally visible research centers. Through this program, the Leibniz Association deepens long-term cooperation among its member institutions and their partners, enhances regional networking, and further expands its international scientific visibility.

Source: Leibniz Institute for Astrophysics Potsdam (AIP)/News

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The Leibniz Institute for Astrophysics Potsdam (AIP) is dedicated to astrophysical questions ranging from the study of our sun to the evolution of the cosmos. The key areas of research focus on stellar, solar and exoplanetary physics as well as extragalactic astrophysics. A considerable part of the institute's efforts aims at the development of research technology in the fields of spectroscopy, robotic telescopes, and e-science. The AIP is the successor of the Berlin Observatory founded in 1700 and of the Astrophysical Observatory of Potsdam founded in 1874. The latter was the world’s first observatory to emphasize explicitly the research area of astrophysics. The AIP has been a member of the Leibniz Association since 1992.

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Prof. Dr.
Christoph Pfrommer
Science contact
Phone: +49 331 7499 513
cpfrommer@aip.de

Tilo Bergemann
Media contact
Phone: +49 331 7499 803
presse@aip.de

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Leibniz Institute for Astrophysics Potsdam (AIP)
An der Sternwarte 16
14482 Potsdam, Germany
Phone: +49 (0) 331 74 99 0
Fax: +49 (0) 331 74 99 209
info@aip.de
[Contact]

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Elliptical Galaxy NGC 7458

NGC 7458
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NGC 7458 is a bright and well-defined elliptical galaxy located in the constellation Cetus. Elliptical galaxies are characterized by a strong concentration of light toward their centers that fades rapidly outward, and they lack the distinct structures seen in spiral galaxies. The overall reddish color of NGC 7458 indicates that it is composed predominantly of old stars. Elliptical galaxies in the present-day Universe are known to contain many very old stars, often more than 10 billion years old.

Distance from Earth: 240 million light-years
Instrument: Hyper Suprime-Cam (HSC)

Source: Subaru Telescope

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Where spiral arms and star formation meet

IC 486

A face-on view of the barred spiral galaxy IC 486, showing a bright, elongated central bar and softly curving, ring-like spiral arms with subtle blue star-forming regions and dark dust lanes, set against a black background dotted with distant galaxies and a few foreground stars.

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A luminous swirl set against the deep black of space, the barred spiral galaxy IC 486 glows with a soft, ethereal light in this new ESA/Hubble Picture of the Month image.

IC 486 lies right on the edge of the constellation Gemini (the Twins), around 380 million light-years from Earth. Classified as a barred spiral galaxy, it features a bright central bar-shaped structure from which its spiral arms unfurl, wrapping around the core in a smooth, almost ring-like pattern.

Hubble’s keen eye reveals subtle variations in colour across the galaxy. The pale, luminous centre is dominated by older stars, while faint bluish regions in the surrounding disc trace pockets of more recent star formation. Wisps of dust thread through the galaxy’s structure, gently obscuring light and tracing regions of increased molecular gas where new stars are likely to form.

At the galaxy’s centre a noticeable white glow outshines the starlight around it. This is light given off by IC 486’s active galactic nucleus (AGN), powered by a supermassive black hole more than 100 million times the mass of the Sun. Every sufficiently large galaxy hosts a supermassive black hole at its centre, but some of these black holes are particularly ravenous, marshalling vast amounts of gas and dust into swirling accretion discs from which they feed. The intense heat generated by the orbiting disc of material generates intense radiation up to and including X-rays, which can outshine the entire rest of the galaxy. In these cases, the galaxy is known as an active galaxy, with an AGN at its centre.

The data used to make this image comes from two separate observing programmes — #17310 (PI: M. J. Koss) and #15444 (PI: A. J. Barth) — with similar aims: to survey nearby active galaxies like IC 486 and record detailed, high-quality images of their central black holes and the stars near the core of the galaxy. By combining Hubble’s sharp imaging with large comprehensive samples, these programmes are enabling detailed comparisons of how stars, gas, dust, and black holes interact in galaxy centres.

A key goal of this work is to understand how galaxies grow by linking their large-scale structures, such as bars and spiral arms, to activity in their nuclei. To achieve this, the research teams are leveraging both expert classifications and citizen science through Galaxy Zoo, with datasets that will ultimately be released to the public. In parallel, the same images are being used to test how well large language models and other machine learning techniques can reproduce or extend human classifications, offering a new way to scale galaxy morphology studies to the largest surveys that are currently being performed with the Euclid telescope.

Beyond IC 486 itself, the image is peppered with distant background galaxies and foreground stars. Some stars appear with characteristic diffraction spikes, while the more diffuse, reddish smudges are far more distant galaxies scattered across the cosmos.

Though it may appear calm and orderly, IC 486 is a dynamic system shaped by gravity and stellar evolution. Over millions of years, its structure will continue to evolve as stars are born, age, and fade, contributing to the ongoing story of galactic life in the Universe.

Source: ESA/Hubble/potm

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Links

• IC 486 (wide-field view)
• Image on ESA website
• Pan video: IC 486
• Pan video: IC 486 (wide-field view)

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NASA's IXPE and Chandra Take a New Look at an Old Supernova

RCW 86
Credit: X-ray: Chandra: NASA/CXC/SAO, XMM: ESA/XMM-NEWTON, IXPE:NASA/MSFC;
Optical: NSF/NOIRLab; Image Processing: NASA/CXC/SAO/J. Schmidt

JPEG (278.7 kb) - Large JPEG (4.2 MB) - Tiff (21.4 MB) - More Images

Tour: NASA's Chandra Rings in New Year With Champagne Cluster (Video)

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RCW 86 is approximately 8,000 light-years from Earth in the Southern constellation of Circinus, occupying a region of the sky slightly larger than the full moon. In the year 185 AD, Chinese astronomers recorded witnessing a “guest star” in this area of the night sky that remained visible for 8 months.

NASA’s IXPE observed the outer rim of the supernova remnant highlighted in purple at the lower right. When NASA’s Chandra X-ray Observatory targeted RCW 86, they discovered that a large “cavity” region around the system led the supernova to expand larger in a shorter amount of time than expected. The low-density cavity region could have led to RCW 86’s unique shape as well.

The full image puts IXPE’s data into context with legacy observations from two other X-ray telescopes: Chandra and the European Space Agency’s XMM-Newton. The yellow represents low-energy X-rays, while blue shows high-energy X-rays detected by Chandra and XMM-Newton. The starfield in the image comes from the National Science Foundation’s National Optical-Infrared Astronomy Research Laboratory (NOIRlab).

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’s Chandra X-ray Observatory

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Visual Description:

This is an X-ray and optical image of supernova remnant RCW 86, which appears to be two slightly mismatched halves of a broken rough circle. The colors in the image are predominantly blue and gold with a spot of bright purple in the lower right corner. The texture of RCW 86 resembles that of nebulous and patchy fingers, and swirls of gas. This image combines data from four different telescopes to create a multi-wavelength view of the remains of an exploded star. X-ray images from NASA's Chandra X-ray Observatory and the ESA's XMM-Newton are combined to form the blue and gold colors in the image. The X-rays show the interstellar gas that has been heated to millions of degrees by the passage of the shock wave from the supernova. Additional X-ray data from NASA's IXPE are shown in purple, confined to a small circle in the lower right where IXPE observed. A faint starfield, a sprinkling of white stars across the image, from NSF's NOIRlab is also included.

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Fast Facts for RCW 86:

Credit: X-ray: Chandra: NASA/CXC/SAO, XMM: ESA/XMM-NEWTON, IXPE:NASA/MSFC; Optical: NSF/NOIRLab; Image Processing: NASA/CXC/SAO/J. Schmid

Release Date: March 25, 2026
Scale: Image is about 43.5 arcmin (101 light-years) across.
Category: Supernovas & Supernova Remnants
Coordinates (J2000): RA 14h 43m 20.6s | Dec -62° 29´ 52.8"
Constellation: Circinus
Observation Dates: 16 observations from Feb 2001–Jan 2021
Observation Time: 164 hours 10 minutes (6 days 20 hours 10 minutes)
Obs. ID: 1993, 2805, 4611, 7642, 10699, 13748, 14890, 15608-15611, 16952, 23597, 24330, 24331, 24931
Instrument: ACIS
Also Known As: G315.4-2.1
References: Silvestri, S. et al, 2026, ApJ, 988, 172.
Color Code: X-ray: (Chandra and XMM) blue and orange, (IXPE) purple; Optical: red, green, blue
Distance Estimate: About 8,000 light-years from Earth.

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An Impostor Explosion

An artist's impression of a collision between two neutron stars releasing gravitational and electromagnetic waves.
Credit: NASA's Goddard Space Flight Center/CI Lab

These images from the Hubble Space Telescope show the fading light of the kilonova associated with the gravitational wave event GW170817. Credit: NASA and ESA Acknowledgment: A. Levan (U. Warwick), N. Tanvir (U. Leicester), and A. Fruchter and O. Fox (STScI)

Over many centuries of observing the night sky, astronomers have found only a single visible afterglow of a collision between neutron stars. For a few days in the summer of 2025, it seemed like observers may have found another of these treasured but elusive prizes; unfortunately, the promising candidate turned out to be a supernova in disguise.

A Rare Prize

When two neutron stars (the ultra-dense remnants of massive stellar explosions) spiral together and collide, the cataclysm is energetic enough to release strong gravitational waves, forge heavy elements, and briefly glow across the electromagnetic spectrum. These events are called kilonovae, and they’re quite rare; while we may have detected a handful at high energies, there is only one event for which astronomers managed to record both gravitational waves and an optical transient.

That one kilonova, found back in 2017, taught astronomers much about how heavy elements are formed and left the scientific community hungry for more data. Since then, each time a gravitational wave detector like LIGO reports that it may have spotted a neutron star merger, telescopes across the world scramble to look in the probable region of the sky, hoping to find the short-lived electromagnetic counterpart.

Too Good to Be True

On 18 August 2025, the LIGO/Virgo/KAGRA collaboration sent out an alert that it may have detected a neutron star–neutron star merger. The odds that their signal was real weren’t great, and the researchers gave it just a 29% chance of being a genuine astrophysical signal. Still, given the potential payoff of finding the next kilonova, several telescopes quickly began searches for the optical counterpart. The gravitational wave signal suggested that the event likely came from a curved patch of sky delightfully referred to as the “northern banana,” and after trawling that region for a few nights, astronomers hauled in 47 new transients. Any one of these could have been the kilonova, and all of them received extensive follow-up observations.

A team led by James Gillanders (University of Oxford) recently summarized some of these follow-up observations carried out with the Pan-STARRS and ATLAS telescopes. In the initial exciting few days after the alert went out, one candidate transient stood out as the most promising. Named AT2025ulz, it was first spotted by the Zwicky Transient Facility and initially started fading rapidly and changing colors, just as models of kilonovae predict. For four days, it seemed like the world may have witnessed its second-ever kilonova. But then the telescopes began their fifth night of observations.

The light curve of SN2025ulz. Note that the source appeared to grow brighter again after about 5 days.
Credit: Gillanders et al. 2025

Supernova Unmasked

A scatter plot showing a rapidly fading, then reversing and spiking, light curve.

The light curve of AT2025ulz, after fading steadily in the preceding days, suddenly turned upwards; in other words, whatever was causing the transient got brighter. Models of kilonova evolution predict no such brightening, but Type IIb supernovae are known to follow just this behavior. AT2025ulz showed itself to be another run-of-the-mill stellar explosion, not the sought-after fireworks of two neutron stars slamming together.

Frustrating as this particular result may be, the effort was far from wasted. The team could use their non-detection of the true kilonova to place limits on its timing and peak magnitude, assuming it existed in the first place. And, as gravitational wave detectors grow more sensitive and alerts like this more common, hindsight will likely frame this scramble as a dress rehearsal for an ultimately successful kilonova recovery effort. Until then, astronomers will keep searching, and will keep their guard up against cosmic impostors.

By Ben Cassese

Citation

“Pan-STARRS Follow-Up of the Gravitational-Wave Event S250818k and the Light Curve of SN2025ulz,” J. H. Gillanders et al 2025 ApJL 995 L27. doi: 10.3847/2041-8213/ae2125

Source: American Astronomical Society - AAS-Nova

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Galactic warming: The ‘car engine-like’ effect heating our Milky Way

An artist’s impression of the Milky Way, with two of its satellite galaxies – the Large Magellanic Cloud and the Small Magellanic Cloud – in the bottom left. Credit: ESA/Gaia/DPAC, S. Payne-Wardenaar, L. McCallum et al (2025), Kevinmloch, F. Fraternali.

Licence type: Attribution (CC BY 4.0)

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Our Milky Way's halo of hot gas is warmer to the 'south' than the 'north' because of an internal combustion engine-like effect that is compressing the gas like a piston, a new study has found.

Computer simulations reveal that the Large Magellanic Cloud – a satellite galaxy below, or on the south side, of our own – attracts the Milky Way, causing gas in the southern half of the halo to compress and heat up.

This, a team of scientists led by the University of Groningen say, explains why the southern half of the halo is up to 12 per cent warmer than the northern part above the Milky Way's disc, a discrepancy which was measured in 2024 by the X-ray observatory eROSITA mounted on a German-Russian space telescope.

Their findings are published today in Monthly Notices of the Royal Astronomical Society.

Many galaxies, including our own, are surrounded by a vast sphere of thin and warm matter, also known as a halo of hot gas.

Scientists estimate that our Milky Way's gaseous halo has a mass of 100 billion solar masses, meaning there is more matter in the halo than in the galactic disc. The halo, which has a temperature of about 2 million degrees kelvin (a few hundred times hotter than the surface of the Sun), is the 'building material' of the much more compact and cooler disc of gas and stars – including the Sun – at the centre of it.

The Milky Way in the computer simulations is made of three 'components': the rotating disc with relatively cold gas, the much warmer gas around it and a large halo consisting of dark matter.

The so-called hydrodynamic simulation calculates movements of these three components caused by the gravitational attraction of the Magellanic Clouds, which are passing close by the Milky Way, over the course of about one billion years.

The results show that the Milky Way's cold disc is currently moving towards the satellite galaxies at about 40 kilometres per second because of the gravity of the Large Magellanic Cloud. In this process, the Milky Way compresses the gas at the bottom and the material heats up 13 to 20 per cent, according to the calculations.

The simulation also shows that the temperature difference between the northern and southern parts of the halo has arisen in the last 100 million years.

"We saw fairly quickly in the simulations that there was a warming effect," said Filippo Fraternali, professor of gas dynamics and the evolution of galaxies at the University of Groningen.

"It took a little longer before we realised what is going on here – namely the compression of gas like in the piston of an internal combustion engine, which then heats up to make the southern side of our Milky Way's halo warmer."

The simulations may also explain more asymmetries around the Milky Way, according to the researchers. For example, many more so-called high-velocity clouds are seen on the north side of the Milky Way than on the south side. These regions of gas – usually about 100 times cooler than the surrounding material – move around the galaxy at highly anomalous speeds.

"The lower pressure of the surrounding gas may make it easier for these clouds to form and survive there," Fraternali added.

Initially, the researchers were not looking for what they discovered. The simulations had already been published in 2019 as part of an attempt to find an explanation for gas moving around the Magellanic Clouds, among other things. At that time, the temperature difference had not yet been found.

"Typically, computer models are designed to explain certain observations. It is remarkable these simulations already contained the temperature asymmetry before it was found. It makes this result extra robust," Fraternali said.

Co-author Else Starkenburg, associate professor at the University of Groningen, added: "Our explanation for the temperature asymmetry measured by eROSITA is based on simple and well-understood physical processes as we also find them in, for example, combustion engines.

"That gives the result extra elegance."

Source: Royal Astronomical Society (RAS)/Research Highlights

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Media contacts:

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

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Science contacts:

Professor Filippo Fraternali
Kapteyn Institute, University of Groningen
fraternali@astro.rug.nl

Professor Else Starkenburg
Kapteyn Institute, University of Groningen
estarkenburg@astro.rug.nl

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Images & captions

Milky Way & the LMC

Caption: An artist’s impression of the Milky Way, with two of its satellite galaxies – the Large Magellanic Cloud and the Small Magellanic Cloud – in the bottom left.

Credit: ESA/Gaia/DPAC, S. Payne-Wardenaar, L. McCallum et al (2025), Kevinmloch, F. Fraternali.

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Further information

The paper ‘Temperature asymmetry in the Milky Way’s hot circumgalactic medium induced by the Magellanic Clouds’ by A. Oprea et al. has been published in Monthly Notices of the Royal Astronomical Society. DOI: 10.1093/mnras/stag319.

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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 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 successful peer review, following which experts on the Editorial Boards accept the papers for publication. 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 Thu, 26/03/2026 - 10:00

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The best places to look for alien life: Scientists identify 45 Earth-like worlds to explore for a 'Project Hail Mary'

A diagram depicting habitable zone boundaries across star type with rocky exoplanets from Bohl et al. (2026). The boundaries of the habitable zone shift based on star colour, since different wavelengths of light will heat a planet's atmosphere differently. Credit: Gillis Lowry / Pablo Carlos Budassi

Licence type: Attribution (CC BY 4.0)

If we're to find extraterrestrial life in the universe, astronomers have pinpointed the best places to look for it.

They have identified just under 50 rocky worlds most likely to be habitable out of the more than 6,000 exoplanets discovered so far.

Their research, published today in Monthly Notices of the Royal Astronomical Society, would be useful in a scenario portrayed in the newly-released Hollywood blockbuster Project Hail Mary, which sees Ryan Gosling's character having to travel to an exoplanet system in search of a way to save Earth.

On the way he encounters an alien lifeform named Rocky and the fictional extraterrestrial micro-organisms Astrophage and Taumoeba.

Professor Lisa Kaltenegger, director of the Carl Sagan Institute at Cornell University, and a team of undergraduate students used new data from the European Space Agency's Gaia mission and the NASA Exoplanet Archive to identify planets in the so-called habitable zone.

This is an area not too close to a host star that it’s too hot, and not too far away that it’s too cold. lt also means that, like Earth, a planet is much more likely to have water on its surface – which is a key ingredient for life.

The paper, titled 'Probing the limits of habitability: a catalogue of rocky exoplanets in the habitable zone', also shortlisted the worlds that receive the most similar energy from their star compared to what Earth gets from our Sun.

An artist’s impression of a planetary system around a slightly hotter star than our Sun. In prior research, Carl Sagan Institute scientists have theorised that organisms could evolve biofluorescence to protect themselves from a more intense star. Credit: Gillis Lowry

Licence type: Attribution (CC BY 4.0)

"As Project Hail Mary so beautifully illustrates, life might be much more versatile than we currently imagine, so figuring out which of the 6,000 known exoplanets would be most likely to host extraterrestrials such as Astrophage and Taumoeba – or Rocky – could prove critical, and not just to Ryan Gosling," Professor Kaltenegger said.

"Our paper reveals where you should travel to find life if we ever built a 'Hail Mary' spacecraft."

The researchers pinpointed 45 rocky worlds that may support life in the habitable zone, and another 24 in a narrower 3D habitable zone that makes a more conservative assumption of how much heat a planet can take before it loses its habitability.

They include some famous exoplanets, including Proxima Centauri b, TRAPPIST-1f and Kepler 186f, as well as others that are not as well known, such as TOI-715 b.

The most interesting planets of those listed, according to the authors, are TRAPPIST-1 d, e, f and g, which are 40 light-years from Earth, as well as LHS 1140 b, which is 48 light-years away. Whether these planets could have liquid water depends in part if they can hold an atmosphere.

The worlds that get light from their stars most similar to what modern Earth receives from the Sun are the transiting planets TRAPPIST-1 e, TOI-715 b, Kepler-1652 b, Kepler-442 b, Kepler-1544 b and the planets Proxima Centauri b, GJ 1061 d, GJ 1002 b, and Wolf 1069 b, which make their stars wobble.

The authors also hope the planets they have identified near the edges of the habitable zone will shed light on exactly where habitability ends and if scientists' theories about those limits are correct. While the idea of the habitable zone has been developed since the 1970s, new observations will be critical in establishing whether certain assumptions need adapting, Professor Kaltenegger said.

An artist's impression of a theoretical planet orbiting a redder star, which could cause microbes and plants on the planet's surface to reflect very different colours from Earth’s green forests. Credit: Gillis Lowry

Licence type: Attribution (CC BY 4.0)

In addition, exoplanets with unusual elliptical orbits around their star can trace the importance of a changing amount of heat hitting a world and help answer the question of whether a planet needs to stay in the habitable zone or can cross in and out of it and still remain habitable.

The transiting planets that can test the limit of habitability on the inner edge are K2-239 d, TOI-700e, K2-3d – as well as the planets Wolf 1061c and GJ 1061c, which make their stars wobble. Trappist-1g and Kepler-441b and GJ 102 can probe the outer edge of habitability where it gets extremely cold, the researchers say.

"While it's hard to say what makes something more likely to have life, identifying where to look is the first key step – so the goal of our project was to say 'here are the best targets for observation'," said Gillis Lowry, now a graduate student at San Francisco State University.

Fellow researcher Lucas Lawrence, now a graduate student at the University of Padua in Italy, said: "We wanted to create something that will enable other scientists to search effectively and we kept discovering new things about these worlds we wanted to investigate further."

Co-author Abigail Bohl, of Cornell University, added: "We know Earth is habitable, while Venus and Mars are not. We can use our Solar System as a reference to search for exoplanets that receive stellar energy between what Venus and Mars get.

"Observing these planets can help us understand when habitability is lost, how much energy is too much, and which planets remain habitable – or maybe never were.

"The same idea applies to eccentric planets: how much orbital eccentricity can a planet have while still holding onto its surface water and habitable conditions?

An artist’s impression of what the TRAPPIST-1 planetary system may look like showing (from left to right) TRAPPIST-1 a, b, c, d, e, f, g and h, based on available data about the planets' diameters, masses and distances from the host star. Of these, TRAPPIST-1 d, e, f and g are thought to be the most Earth-like planets. Credit: NASA/JPL-Caltech

Licence type: Attribution (CC BY 4.0)

"We identified planets at the inner and outer edges of the habitable zone, as well as those with the highest eccentricities, to test our understanding of what it takes for a planet to be and remain habitable. We also identified the targets that are most observable with the James Webb Space Telescope (JWST) and other telescopes."

The students also earmarked the best planets to observe with different techniques, to give scientists the best odds of finding signs of life if they exist on these worlds.

The list they've created will guide astronomers studying the night sky with JWST, the upcoming Nancy Grace Roman Space Telescope (set to launch in 2027), the Extremely Large Telescope (set to see first light in 2029), the Habitable Worlds Observatory (expected to launch in the 2040s) and the proposed Large Interferometer For Exoplanets (LIFE) project.

Observing these small exoplanets is the only way to confirm if they have atmospheres, and whether astronomers need to refine their ideas of what limits the habitable zone, Lowry said.

She added that she's already been using the list to take an early look at the 10 planets that receive very similar radiation to Earth, identifying two that are close enough to study with current or upcoming telescopes: TRAPPIST-1 e and TOI-715 b.

The TRAPPIST-1 planetary system is a main focus of observation with the JWST telescope, a programme led by Nikole Lewis, associate professor of astronomy at Cornell. Trappist-1 and TOI-715 b are both small red stars, making it easier to see the small, Earth-sized planets orbiting around them.

Source: Royal Astronomical Society (RAS)/Research Highlights

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Media contacts:

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

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Science contacts:

Professor Lisa Kaltenegger
Director of the Carl Sagan Institute at Cornell University
lk433@cornell.edu

Abigail Bohl
Cornell University
acb338@cornell.edu

Gillis Lowry
San Francisco State University
gel62@cornell.edu

Lucas Lawrence
University of Padua
lucaslawrence000@gmail.com

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Images & captions

Habitable zone planets diagram

Caption: A diagram depicting habitable zone boundaries across star type with rocky exoplanets from Bohl et al. (2026). The boundaries of the habitable zone shift based on star colour, since different wavelengths of light will heat a planet's atmosphere differently.

Credit: Gillis Lowry / Pablo Carlos Budassi

Earth-like exoplanet

Caption: An artist's impression of a planetary system around a slightly hotter star than our Sun. In prior research, Carl Sagan Institute scientists have theorised that organisms could evolve biofluorescence to protect themselves from a more intense star.

Credit: Gillis Lowry

Purple planet

Caption: An artist's impression of a theoretical planet orbiting a redder star, which could cause microbes and plants on the planet's surface to reflect very different colours from Earth's green forests.

Credit: Gillis Lowry

TRAPPIST-1 planetary system

Caption: An artist's impression of what the TRAPPIST-1 planetary system may look like showing (from left to right) TRAPPIST-1 a, b, c, d, e, f, g and h, based on available data about the planets' diameters, masses and distances from the host star. Of these, TRAPPIST-1 d, e, f and g are thought to be the most Earth-like planets.

Credit: NASA/JPL-Caltech

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Further information

The paper ‘Probing the limits of habitability: a catalogue of rocky exoplanets in the habitable zone’ by Bohl et al. has been published in Monthly Notices of the Royal Astronomical Society. DOI: 10.1093/mnras/stag028

The full list of the 45 exoplanets identified in the paper:

GJ 1002 b - GJ 1002 c
GJ 1061 c - GJ 1061 d
GJ 251 c - GJ 273 b
GJ 3323 b
GJ 667 C c - GJ 667 C e - GJ 667 C f
GJ 682 b
K2-239 d
K2-288 B b
K2-3 d
K2-72 e
Kepler-1229 b
Kepler-1410 b
Kepler-1544 b
Kepler-1606 b
Kepler-1649 c
Kepler-1652 b
Kepler-186 f
Kepler-296 e - Kepler-296 f
Kepler-441 b
Kepler-442 b
Kepler-452 b
Kepler-62 e - Kepler-62 f
L 98-59 f
LHS 1140 b
LP 890-9 c
Proxima Centauri b
Ross 508 b
TOI-1266 d
TOI-700 d - TOI-700 e
TOI-715 b
TRAPPIST-1 d - TRAPPIST-1 e - TRAPPIST-1 f - TRAPPIST-1 g
Teegarden's Star c
v > Wolf 1061 c
Wolf 1069 b

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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.

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Submitted by Sam Tonkin on Thu, 19/03/2026 - 10:18

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