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By NASA
6 Min Read NASA’s Chandra Shares a New View of Our Galactic Neighbor
The Andromeda galaxy, also known as Messier 31 (M31), is the closest spiral galaxy to the Milky Way at a distance of about 2.5 million light-years. Astronomers use Andromeda to understand the structure and evolution of our own spiral, which is much harder to do since Earth is embedded inside the Milky Way.
The galaxy M31 has played an important role in many aspects of astrophysics, but particularly in the discovery of dark matter. In the 1960s, astronomer Vera Rubin and her colleagues studied M31 and determined that there was some unseen matter in the galaxy that was affecting how the galaxy and its spiral arms rotated. This unknown material was named “dark matter.” Its nature remains one of the biggest open questions in astrophysics today, one which NASA’s upcoming Nancy Grace Roman Space Telescope is designed to help answer.
X-ray: NASA/CXO/UMass/Z. Li & Q.D. Wang, ESA/XMM-Newton; Infrared: NASA/JPL-Caltech/WISE, Spitzer, NASA/JPL-Caltech/K. Gordon (U. Az), ESA/Herschel, ESA/Planck, NASA/IRAS, NASA/COBE; Radio: NSF/GBT/WSRT/IRAM/C. Clark (STScI); Ultraviolet: NASA/JPL-Caltech/GALEX; Optical: Andromeda, Unexpected © Marcel Drechsler, Xavier Strottner, Yann Sainty & J. Sahner, T. Kottary. Composite image processing: L. Frattare, K. Arcand, J.Major This new composite image contains data of M31 taken by some of the world’s most powerful telescopes in different kinds of light. This image includes X-rays from NASA’s Chandra X-ray Observatory and ESA’s (European Space Agency’s) XMM-Newton (represented in red, green, and blue); ultraviolet data from NASA’s retired GALEX (blue); optical data from astrophotographers using ground based telescopes (Jakob Sahner and Tarun Kottary); infrared data from NASA’s retired Spitzer Space Telescope, the Infrared Astronomy Satellite, COBE, Planck, and Herschel (red, orange, and purple); and radio data from the Westerbork Synthesis Radio Telescope (red-orange).
The Andromeda Galaxy (M31) in Different Types of Light.X-ray: NASA/CXO/UMass/Z. Li & Q.D. Wang, ESA/XMM-Newton; Infrared: NASA/JPL-Caltech/WISE, Spitzer, NASA/JPL-Caltech/K. Gordon (U. Az), ESA/Herschel, ESA/Planck, NASA/IRAS, NASA/COBE; Radio: NSF/GBT/WSRT/IRAM/C. Clark (STScI); Ultraviolet: NASA/JPL-Caltech/GALEX; Optical: Andromeda, Unexpected © Marcel Drechsler, Xavier Strottner, Yann Sainty & J. Sahner, T. Kottary. Composite image processing: L. Frattare, K. Arcand, J.Major Each type of light reveals new information about this close galactic relative to the Milky Way. For example, Chandra’s X-rays reveal the high-energy radiation around the supermassive black hole at the center of M31 as well as many other smaller compact and dense objects strewn across the galaxy. A recent paper about Chandra observations of M31 discusses the amount of X-rays produced by the supermassive black hole in the center of the galaxy over the last 15 years. One flare was observed in 2013, which appears to represent an amplification of the typical X-rays seen from the black hole.
These multi-wavelength datasets are also being released as a sonification, which includes the same wavelengths of data in the new composite. In the sonification, the layer from each telescope has been separated out and rotated so that they stack on top of each other horizontally, beginning with X-rays at the top and then moving through ultraviolet, optical, infrared, and radio at the bottom. As the scan moves from left to right in the sonification, each type of light is mapped to a different range of notes, from lower-energy radio waves up through the high energy of X-rays. Meanwhile, the brightness of each source controls volume, and the vertical location dictates the pitch.
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In this sonification of M31, the layers from each telescope has been separated out and rotated so that they stack on top of each other horizontally beginning with X-rays at the top and then moving through ultraviolet, optical, infrared, and radio at the bottom. As the scan moves from left to right in the sonification, each type of light is mapped to a different range of notes ranging from lower-energy radio waves up through the high-energy of X-rays. Meanwhile, the brightness of each source controls volume and the vertical location dictates the pitch.NASA/CXC/SAO/K.Arcand, SYSTEM Sounds (M. Russo, A. Santaguida This new image of M31 is released in tribute to the groundbreaking legacy of Dr. Vera Rubin, whose observations transformed our understanding of the universe. Rubin’s meticulous measurements of Andromeda’s rotation curve provided some of the earliest and most convincing evidence that galaxies are embedded in massive halos of invisible material — what we now call dark matter. Her work challenged long-held assumptions and catalyzed a new era of research into the composition and dynamics of the cosmos. In recognition of her profound scientific contributions, the United States Mint has recently released a quarter in 2025 featuring Rubin as part of its American Women Quarters Program — making her the first astronomer honored in the series.
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.
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
Visual Description
This release features several images and a sonification video examining the Andromeda galaxy, our closest spiral galaxy neighbor. This collection helps astronomers understand the evolution of the Milky Way, our own spiral galaxy, and provides a fascinating insight into astronomical data gathering and presentation.
Like all spiral galaxies viewed at this distance and angle, Andromeda appears relatively flat. Its spiraling arms circle around a bright core, creating a disk shape, like a large dinner plate. In most of the images in this collection, Andromeda’s flat surface is tilted to face our upper left.
This collection features data from some of the world’s most powerful telescopes, each capturing light in a different spectrum. In each single-spectrum image, Andromeda has a similar shape and orientation, but the colors and details are dramatically different.
In radio waves, the spiraling arms appear red and orange, like a burning, loosely coiled rope. The center appears black, with no core discernible. In infrared light, the outer arms are similarly fiery. Here, a white spiraling ring encircles a blue center with a small golden core. The optical image is hazy and grey, with spiraling arms like faded smoke rings. Here, the blackness of space is dotted with specks of light, and a small bright dot glows at the core of the galaxy. In ultraviolet light the spiraling arms are icy blue and white, with a hazy white ball at the core. No spiral arms are present in the X-ray image, making the bright golden core and nearby stars clear and easy to study.
In this release, the single-spectrum images are presented side by side for easy comparison. They are also combined into a composite image. In the composite, Andromeda’s spiraling arms are the color of red wine near the outer edges, and lavender near the center. The core is large and bright, surrounded by a cluster of bright blue and green specks. Other small flecks in a variety of colors dot the galaxy, and the blackness of space surrounding it.
This release also features a thirty second video, which sonifies the collected data. In the video, the single-spectrum images are stacked vertically, one atop the other. As the video plays, an activation line sweeps across the stacked images from left to right. Musical notes ring out when the line encounters light. The lower the wavelength energy, the lower the pitches of the notes. The brighter the source, the louder the volume.
News Media Contact
Megan Watzke
Chandra X-ray Center
Cambridge, Mass.
617-496-7998
mwatzke@cfa.harvard.edu
Lane Figueroa
Marshall Space Flight Center, Huntsville, Alabama
256-544-0034
lane.e.figueroa@nasa.gov
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Last Updated Jun 25, 2025 EditorLee MohonContactLane Figueroa Related Terms
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NASA-Assisted Scientists Get Bird’s-Eye View of Population Status
Through the eBird citizen scientist program, millions of birders have recorded their observations of different species and submitted checklists to the Cornell Lab of Ornithology. Through a partnership with NASA, the lab has now used this data to model and map bird population trends for nearly 500 North American species.
Led by Alison Johnston of the University of St. Andrews in Scotland, the researchers reported that 75% of bird species in the study are declining at wide-range scales. And yet this study has some good news for birds. The results, published in Science in May, offer insights and projections that could shape the future conservation of the places where birds make their homes.
“This project demonstrates the power of merging in situ data with NASA remote sensing to model biological phenomena that were previously impossible to document,” said Keith Gaddis, NASA’s Biological Diversity and Ecological Forecasting program manager at the agency’s headquarters in Washington, who was not involved in the study. “This data provides not just insight into the Earth system but also provides actionable guidance to land managers to mitigate biodiversity loss.”
Rock wren in Joshua Tree National Park. National Park Service / Jane Gamble A team from Cornell, the University of St. Andrews, and the American Bird Conservancy used land imaging data from NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS) instruments to distinguish among such specific bird habitats as open forests, dense shrublands, herbaceous croplands, and forest/cropland mosaics. They also drew on NASA weather information and water data that matched the dates and times when birders made their reports.
When combined with a 14-year set of eBird checklists — 36 million sets of species observations and counts, keyed directly to habitats — the satellite data gave researchers almost a strong foundation to produce a clear picture of the health of bird populations. But there was one missing piece.
Wrestling with Wren Data
While some eBird checklists come from expert birders who’ve hiked deep into wildlife preserves, others are sent in by novices watching bird feeders and doing the dishes. This creates what Cornell statistician Daniel Fink described as “an unstructured, very noisy data set,” complete with gaps in the landscape that birders did not reach and, ultimately, some missing birds.
To account for gaps where birds weren’t counted, the researchers trained machine learning models to fill in the maps based on the remote sensing data. “For every single species — say the rock wren — we’ve created a simulation that mimics the species and a variety of ways that it could respond to changes in the environment,” Johnston said. “Thousands of simulations underlie the results we showed.”
CornellLab eBird The researchers achieved unprecedented resolution, zeroing in on areas 12 miles by 12 miles (27 km by 27 km), the same area as Portland, Oregon. This new population counting method can also be applied to eBird data from other locations, Fink said. “Now we’re using modeling to track bird populations — not seasonally through the year, but acrossthe years — a major milestone,” he added.
“We’ve been able to take citizen science data and, through machine learning methodology, put it on the same footing as traditionally structured surveys, in terms of the type of signal we can find,” said Cornell science product manager Tom Auer. “It will increase the credibility and confidence of people who use this information for precise conservation all over the globe.”
The Up Side
Since 1970, North America has lost one-quarter of its breeding birds, following a global trend of declines across species. The causes range from increased pollution and land development to changing climate and decreased food resources. Efforts to reverse this loss depend on identifying the areas where birds live at highest risk, assessing their populations, and pinpointing locations where conservation could help most.
For 83% of the reported species in the new study, the decline was greatest in spots where populations had previously been most abundant — indicating problems with the habitat.
“Even in species where populations are declining a lot, there are still places of hope, where the populations are going up,” Johnston said. The team found population increases in the maps of 97% of the reported species. “That demonstrates that there’s opportunity for those species.”
“Birds face so many challenges,” said Cornell conservationist Amanda Rodewald. “This research will help us make strategic decisions about making changes that are precise, effective, and less costly. This is transformative. Now we can really drill in and know where specifically we’re going to be able to have the most positive impact in trying to stem bird declines.”
By Karen Romano Young
NASA Headquarters, Washington
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By NASA
5 Min Read 3 Black Holes Caught Eating Massive Stars in NASA Data
A disk of hot gas swirls around a black hole in this illustration. Some of the gas came from a star that was pulled apart by the black hole, forming the long stream of hot gas on the right, feeding into the disk. Credits:
NASA/JPL-Caltech Black holes are invisible to us unless they interact with something else. Some continuously eat gas and dust, and appear to glow brightly over time as matter falls in. But other black holes secretly lie in wait for years until a star comes close enough to snack on.
Scientists have recently identified three supermassive black holes at the centers of distant galaxies, each of which suddenly brightened when it destroyed a star and then stayed bright for several months. A new study using space and ground-based data from NASA, ESA (European Space Agency), and other institutions presents these rare occurrences as a new category of cosmic events called “extreme nuclear transients.”
Looking for more of these extreme nuclear transients could help unveil some of the most massive supermassive black holes in the universe that are usually quiet.
“These events are the only way we can have a spotlight that we can shine on otherwise inactive massive black holes,” said Jason Hinkle, graduate student at the University of Hawaii and lead author of a new study in the journal Science Advances describing this phenomenon.
The black holes in question seem to have eaten stars three to 10 times heavier than our Sun. Feasting on the stars resulted in some of the most energetic transient events ever recorded.
This illustration shows a glowing stream of material from a star as it is being devoured by a supermassive black hole. When a star passes within a certain distance of a black hole — close enough to be gravitationally disrupted — the stellar material gets stretched and compressed as it falls into the black hole. NASA/JPL-Caltech These events as unleash enormous amount of high-energy radiation on the central regions of their host galaxies. “That has implications for the environments in which these events are occurring,” Hinkle said. “If galaxies have these events, they’re important for the galaxies themselves.”
The stars’ destruction produces high-energy light that takes over 100 days to reach peak brightness, then more than 150 days to dim to half of its peak. The way the high-energy radiation affects the environment results in lower-energy emissions that telescopes can also detect.
One of these star-destroying events, nicknamed “Barbie” because of its catalog identifier ZTF20abrbeie, was discovered in 2020 by the Zwicky Transient Facility at Caltech’s Palomar Observatory in California, and documented in two 2023 studies. The other two black holes were detected by ESA’s Gaia mission in 2016 and 2018 and are studied in detail in the new paper.
NASA’s Neil Gehrels Swift Observatory was critical in confirming that these events must have been related to black holes, not stellar explosions or other phenomena. The way that the X-ray, ultraviolet, and optical light brightened and dimmed over time was like a fingerprint matching that of a black hole ripping a star apart.
Scientists also used data from NASA’s WISE spacecraft, which was operated from 2009 to 2011 and then was reactivated as NEOWISE and retired in 2024. Under the WISE mission the spacecraft mapped the sky at infrared wavelengths, finding many new distant objects and cosmic phenomena. In the new study, the spacecraft’s data helped researchers characterize dust in the environments of each black hole. Numerous ground-based observatories additionally contributed to this discovery, including the W. M. Keck Observatory telescopes through their NASA-funded archive and the NASA-supported Near-Earth Object surveys ATLAS, Pan-STARRS, and Catalina.
“What I think is so exciting about this work is that we’re pushing the upper bounds of what we understand to be the most energetic environments of the universe,” said Anna Payne, a staff scientist at the Space Telescope Science Institute and study co-author, who helped look for the chemical fingerprints of these events with the University of Hawaii 2.2-meter Telescope.
A Future Investigators in NASA Earth and Space Science and Technology (FINESST) grant from the agency helped enable Hinkle to search for these black hole events. “The FINESST grant gave Jason the freedom to track down and figure out what these events actually were,” said Ben Shappee, associate professor at the Institute for Astronomy at the University of Hawaii, a study coauthor and advisor to Hinkle.
Hinkle is set to follow up on these results as a postdoctoral fellow at the University of Illinois Urbana-Champaign through the NASA Hubble Fellowship Program. “One of the biggest questions in astronomy is how black holes grow throughout the universe,” Hinkle said.
The results complement recent observations from NASA’s James Webb Space Telescope showing how supermassive black holes feed and grow in the early universe. But since only 10% of early black holes are actively eating gas and dust, extreme nuclear transients — that is, catching a supermassive black hole in the act of eating a massive star — are a different way to find black holes in the early universe.
Events like these are so bright that they may be visible even in the distant, early universe. Swift showed that extreme nuclear transients emit most of their light in the ultraviolet. But as the universe expands, that light is stretched to longer wavelengths and shifts into the infrared — exactly the kind of light NASA’s upcoming Nancy Grace Roman Space Telescope was designed to detect.
With its powerful infrared sensitivity and wide field of view, Roman will be able to spot these rare explosions from more than 12 billion years ago, when the universe was just a tenth of its current age. Scheduled to launch by 2027, and potentially as early as fall 2026, Roman could uncover many more of these dramatic events and offer a new way to explore how stars, galaxies, and black holes formed and evolved over time.
“We can take these three objects as a blueprint to know what to look for in the future,” Payne said.
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Scientists have discovered a star behaving like no other seen before, giving fresh clues about the origin of a new class of mysterious objects.X-ray: NASA/CXC/ICRAR, Curtin Univ./Z. Wang et al.; Infrared: NASA/JPL/CalTech/IPAC; Radio: SARAO/MeerKAT; Image processing: NASA/CXC/SAO/N. Wolk An unusual star (circled in white at right) behaving like no other seen before and its surroundings are featured in this composite image released on May 28, 2025. A team of astronomers combined data from NASA’s Chandra X-ray Observatory and the Square Kilometer Array Pathfinder (ASKAP) radio telescope on Wajarri Country in Australia to study the discovered object, known as ASKAP J1832−0911 (ASKAP J1832 for short).
ASKAP J1832 belongs to a class of objects called “long period radio transients” discovered in 2022 that vary in radio wave intensity in a regular way over tens of minutes. This is thousands of times longer than the length of the repeated variations seen in pulsars, which are rapidly spinning neutron stars that have repeated variations multiple times a second. ASKAP J1832 cycles in radio wave intensity every 44 minutes, placing it into this category of long period radio transients. Using Chandra, the team discovered that ASKAP J1832 is also regularly varying in X-rays every 44 minutes. This is the first time that such an X-ray signal has been found in a long period radio transient.
Image credit: X-ray: NASA/CXC/ICRAR, Curtin Univ./Z. Wang et al.; Infrared: NASA/JPL/CalTech/IPAC; Radio: SARAO/MeerKAT; Image processing: NASA/CXC/SAO/N. Wolk
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