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NASA’s Chandra Unveils Mysterious X-Ray Objects

✇NASA Breaking News
9 September 2026 at 14:11
Researchers found 84 so-called hypersoft X-ray sources in M101, Messier 31, and four elliptical galaxies. This newly-discovered class of objects give off very low-energy X-rays and likely high levels of ultraviolet light. Their existence may help explain questions around Type Ia supernova explosions and the intergalactic medium. These images of the face-on spiral galaxy M101 show X-ray data from Chandra and an optical image from the Hubble Space Telescope.
X-ray: NASA/CXC/Univ. of Alabama/M. Muhibullah et al.; Optical: NASA/ESA/STScI; Image Processing: NASA/CXC/SAO/N. Wolk

Using NASA’s Chandra X-ray Observatory, scientists have discovered a new class of objects behaving unlike any they have seen before. Astronomers suggest these newly spotted objects in other galaxies may help solve not one, but two long-standing questions in astrophysics.

These mysterious objects give off unusually low-energy X-rays but intense levels of ultraviolet radiation. This discovery is featured in a paper published Wednesday in Nature Astronomy.

“We’ve never encountered a group of objects that act like this,” said Mustafa Muhibullah of the University of Alabama who led the study. “Of course, the next step was to try to figure out what these things are.”

Researchers found 84 so-called hypersoft X-ray sources in M101, Messier 31, and four elliptical galaxies. This newly-discovered class of objects give off very low-energy X-rays and likely high levels of ultraviolet light. Their existence may help explain questions around Type Ia supernova explosions and the intergalactic medium. These images of the face-on spiral galaxy M101 show X-ray data from Chandra and an optical image from the Hubble Space Telescope.
M101 with illustrated circles calling out seven of the newly-discovered objects.
X-ray: NASA/CXC/Univ. of Alabama/M. Muhibullah et al.; Optical: NASA/ESA/STScI; Image Processing: NASA/CXC/SAO/N. Wolk

The researchers found a total of 84 of these “hypersoft X-ray sources” – so named because they give such low-energy X-rays – in the six different galaxies they searched, using data openly available to the public in the Chandra archive. Two of the galaxies are spirals, M31 (the Andromeda galaxy) and M101 (the Pinwheel galaxy), while the other four are ellipticals. They found hypersoft X-ray sources both in regions of active star formation and areas where there are older stars.

The team spotted the sources by finding objects that appeared in Chandra images taken at the lowest X-ray energies but vanished in higher-energy images. That means these objects give off far more low-energy X-rays than high-energy ones. Because low-energy X-rays border energetic ultraviolet radiation on the electromagnetic spectrum, the researchers determined that these sources are producing large amounts of energetic ultraviolet radiation as well.

It is unclear what types of objects are responsible for these low-energy X-rays and intense ultraviolet radiation. The team thinks they most likely involve a black hole, neutron star, or white dwarf pulling material from a companion star. The material pulled from the companion star is heated up to produce X-rays before falling onto the white dwarf or neutron star, or into the black hole. Such binary systems have been seen before, but not with such bright ultraviolet radiation and low-energy X-rays.

The discovery suggests that there may be large populations of binary systems with energetic ultraviolet radiation that have been undetected until now.

“These clandestine X-ray sources are actually among the most energetic objects in galaxies, and they could be solving two cosmic mysteries at once,” said Muhibullah.

Scientists think that some white dwarf systems pulling material from companion stars may eventually explode as a supernova – known as a Type Ia – that is critical for measuring the expansion of the universe. These supernovae played a key role in discovering that this expansion is accelerating. Astronomers have been looking for the stars that turn into Type Ia supernovae for many years, so far without success.

“If we could find a way to spot these Type Ia supernova explosions before they go off, that would be really important,” said co-author Jimmy Irwin, also of the University of Alabama. “Right now, we study them after they’ve exploded, and astronomers have struggled to understand what is actually ignited.”

The other mystery these hypersoft X-ray sources might explain is what strips electrons from gas between the stars in some galaxies. This stripping of electrons is important to probe because it can affect how quickly stars form and influence the life cycles of galaxies. Hot, massive stars play a role, but they do not completely explain what is causing this stripping. The intense levels of ultraviolet radiation from the hypersoft X-ray sources may play a vital role.

Why were these hypersoft X-ray sources not found until now? In addition to the low-energy X-ray output, which is very difficult for X-ray telescopes to detect, the high-energy ultraviolet radiation is readily absorbed by helium and hydrogen gas that fills the space between the stars, creating a nearly impenetrable barrier to look through.

“By combing through the Chandra archive, we were able to eliminate what used to be a blind spot for telescopes,” said co-author Rosanne Di Stefano of the Center for Astrophysics | Harvard & Smithsonian. “That’s how we found what appears to be a new class of cosmic objects with remarkable qualities.”

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

To learn more about NASA’s Chandra mission, visit:

https://www.nasa.gov/chandra

Visual Description

This release features a composite image of a spiral galaxy, M101; one of six identified galaxies housing a new class of mysterious objects that give off unusually low-energy X-rays.

In this composite image, M101 faces us directly. It has multiple arms in shades of purple, spiraling clockwise around a golden yellow core. Scattered along and between the arms are scores of tiny specks in white and purple. Most of those specks are pairs of stars, but seven of them are a mystery.

To casual observers, the unusual objects are visually indistinguishable from the other specks of light in the galaxy. An annotated version of the composite image is included in this release, with red circles around the mysterious specks for easy identification.

These mystery specks behave like no other class of object discovered before. The curious objects give off X-rays of such low energy, they in fact produce large amounts of ultraviolet radiation, as UV radiation borders X-rays on the electromagnetic spectrum. Searching images of galaxies with low-energy X-rays in the Chandra Observatory archive, scientists have found a total of 84 such objects spread across M101 and five other galaxies. They have dubbed these mysterious objects “hypersoft X-ray sources.”

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Last Updated
Sep 09, 2026
Editor
Lee Mohon
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Marshall Space Flight Center

9 Things to Know About NASA’s Nancy Grace Roman Space Telescope

✇NASA Breaking News
27 August 2026 at 13:47

NASA’s Nancy Grace Roman Space Telescope is set to launch at 7:26 a.m. EDT on Sunday, Aug. 30. While you wait to watch the launch, brush up on some key facts about this wide-view mission.

Roman observatory being encapsulated
Teams inside the Payload Hazardous Servicing Facility at NASA’s Kennedy Space Center in Florida encapsulate the agency’s Nancy Grace Roman Space Telescope within the payload fairing on Friday, Aug. 21, 2026, ahead of mating to a SpaceX Falcon Heavy rocket. Encapsulation shields the spacecraft during rollout, ascent, and the early phases of flight. Roman will investigate dark energy and dark matter, conduct a statistical census of planetary systems, and enable a broad range of additional astrophysics research. Liftoff from Launch Complex 39A at Kennedy is targeted for no earlier than Sunday, Aug. 30, 2026.
NASA/Sydney Rohde (Rocz)

  • 01

    The mission is named after NASA’s first chief astronomer, Dr. Nancy Grace Roman.

    Roman is named after Dr. Nancy Grace Roman (1925–2018), NASA’s first chief of astronomy. She championed space-based observatories that could study the universe above Earth’s hazy atmosphere while making their data broadly available to the scientific community.
     
    While she’s known as the “mother” of the Hubble Space Telescope, Roman played an even broader role as the driving force behind NASA’s entire Great Observatories program, which included Hubble along with the Chandra X-ray Observatory and the retired Compton Gamma Ray Observatory and Spitzer Space Telescope.
     
    Her vision and leadership helped establish NASA as a world-class scientific institution and laid the foundation for generations of space telescopes that continue to expand humanity’s understanding of the cosmos.

  • 02

    Roman will transform our view of the cosmos by showing us the bigger picture.

    Roman will pair a large field of view with crisp infrared vision to scan vast, deep swaths of sky. This flagship mission is designed to help astronomers explore dark matter, dark energy, and planets outside our solar system, called exoplanets.
     
    Since each of Roman’s surveys will sample such a large volume of the cosmos, the mission will also offer practically limitless opportunities for astronomers to conduct a broad range of additional science. From objects in our outer solar system and exploding stars to growing black holes and galaxies by the billions, very little will be beyond Roman’s reach. Roman’s data will be made public as soon as it’s processed, allowing many teams to analyze it simultaneously.

  • 03

    The observatory will journey a million miles to join Webb at Lagrange point 2.

    Roman will orbit 1 million miles away at the second Sun-Earth Lagrange point (L2), the same location as NASA’s James Webb Space Telescope. At L2, gravity from the Sun and Earth works together with an object’s motion around the Sun to hold it roughly in place. This balance will give Roman a relatively steady orbit without using much fuel.
     
    Like Webb, Roman will trace out a large orbit around the actual L2 point — much larger than the Moon’s orbit around Earth — and the two will easily be kept far apart.

  • 04

    The spacecraft carries the names of more than a million people.

    This summer, everyone was invited to submit their name to be added to a memory card attached to a plaque on the Roman spacecraft. More than 1.3 million people did so and will have their names carried all the way to L2.

  • 05

    Roman will scan the skies for at least five years.

    Roman will have a primary mission lifetime of five years and is designed to support an additional five-year extended mission. Fuel is expected to be the mission’s life-limiting resource, and while NASA does not currently have an ability to service observatories at L2, Roman is designed to be refuelable.

  • 06

    Two instruments will enable myriad discoveries.

    The observatory’s Wide Field Instrument is a 300-megapixel infrared camera that will give Roman the same sharpness (angular resolution) as Hubble but with a field of view at least 100 times larger. Using this instrument, each Roman image will capture a patch of the sky about 1.5 times bigger than the apparent size of a full Moon.
     
    Roman’s Coronagraph Instrument is designed to demonstrate the most advanced technologies ever flown in space for directly imaging planets around other stars. It will block the glare from stars and make it possible for scientists to see the faint reflected light from planets in orbit around them, revealing giant worlds that are older, colder, and in closer orbits than the hot, young super-Jupiters direct imaging has mainly revealed so far.

  • 07

    Roman joins an international cohort of teamworking telescopes.

    Roman will work in tandem with many other NASA-led and international missions to provide the most complete view of our universe yet. Roman’s large panoramas will uncover interesting targets that Hubble could follow up on using infrared, visible, and ultraviolet light to offer a more comprehensive view. NASA’s James Webb Space Telescope can then use its larger mirror and more powerful vision to deliver even more detailed, ultra-sharp observations. And Roman can view regions around objects Hubble or Webb observe to offer context.
     
    Euclid, an ESA (European Space Agency) mission with key contributions from NASA, will observe a larger area of the sky than Roman, though with less detail. Since their survey areas will overlap, scientists can use Roman’s higher-quality data to apply corrections to Euclid’s, then extend these refinements over Euclid’s much larger area.
     
    Scientists can also pair Roman’s infrared data with visible-light observations from the ground-based Vera C. Rubin Observatory, a National Science Foundation–Department of Energy collaboration. That will allow astronomers to inch closer to achieving Roman-like quality over Rubin’s much greater sky coverage.
     
    By showcasing technology to directly photograph Jupiter-like exoplanets, Roman will also provide a crucial stepping stone for NASA’s Habitable Worlds Observatory concept, a flagship space telescope that would be designed to photograph Earth-like planets in other solar systems for the first time ever.

  • 08

    Watch the Roman launch live from anywhere.

    NASA will stream this event live through a variety of platforms. Learn where to watch online: nasa.gov/live. The launch broadcast will continue until approximately one hour past launch to follow the first several critical milestones post-launch.

  • 09

    NASA expects to share Roman’s first images by early 2027.

    The Roman team will complete a carefully orchestrated series of deployments, calibrations, and tests in the three months following launch before the observatory reaches its final orbit. Science operations begin once this commissioning period is completed, starting with the release of Roman’s first science images.

To learn more about the Roman mission, visit:

https://www.nasa.gov/roman

Media contact:

Claire Andreoli
NASA’s Goddard Space Flight Center, Greenbelt, Md.
claire.andreoli@nasa.gov
301-286-1940

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Last Updated
Aug 27, 2026
Editor
Ashley Balzer
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Ashley Balzer

Galactic Gems Glisten in New Gallery From NASA’s Chandra

✇NASA Breaking News
25 August 2026 at 12:13
4 Min Read

Galactic Gems Glisten in New Gallery From NASA’s Chandra

A spiral galaxy viewed from its side, featuring a giant halo of hot gas blowing out of its stellar disk. X-rays from Chandra and ESA’s XMM-Newton (purple and royal blue) trace hot gas driven out by supernovas and black holes and neutron stars pulling gas from their companions, while optical light (light blue, gold and white) from ground-based observer R. Jay GaBany showcases dense dust lanes. Edge-on views of galaxies allow astronomers to study how flat their stellar disks are and provide the clearest views of material located above or below the disk.

Galaxies are like cosmic gems, each with characteristics including size and shape that make them distinct. A new gallery released today from NASA’s Chandra X-ray Observatory and other telescopes displays a collection of galactic images that showcase this variety.

Astronomers put galaxies into three main categories: spirals like our own Milky Way with arms emanating from their cores, ellipticals that are older and likely the results of mergers, and irregulars that can encompass a wide range of galactic phenomena.

This gallery displays a collection of 16 galactic images from Chandra and other telescopes. Astronomers put galaxies into three main categories: spirals like our own Milky Way, ellipticals that are older and likely the results of mergers, and irregulars that can encompass a wide range of galactic phenomena. All types are represented in this collection. Each galactic image contains X-ray data from Chandra combined with data from telescopes such as NASA’s Webb, Hubble, IXPE, Swift, and NuSTAR, and others both in space and on the ground.
This gallery displays a collection of 16 galactic images from Chandra and other telescopes. Astronomers put galaxies into three main categories: spirals like our own Milky Way, ellipticals that are older and likely the results of mergers, and irregulars that can encompass a wide range of galactic phenomena. All types are represented in this collection. Each galactic image contains X-ray data from Chandra combined with data from telescopes such as NASA’s Webb, Hubble, IXPE, Swift, and NuSTAR, and others both in space and on the ground.
Credit: NASA/CXC/SAO

See full gallery

Just as gems reveal the history of Earth through how they were forged over billions of years, these galactic gems are a way to study Earth’s place in our home galaxy of the Milky Way. By looking outward to other galaxies, we learn more about our own – including clues to its past and future.

There are 16 new images in this galactic gallery. Each one contains X-ray data from Chandra that has been collected across Chandra’s decades in space. This high-energy data has been combined with data from telescopes such as NASA’s James Webb and Hubble Space Telescopes, IXPE (Imaging X-ray Polarimetry Explorer), Neil Gehrels Swift Observatory, NuSTAR (Nuclear Spectroscopic Telescope Array), and others both on the ground and in space.

A barred spiral galaxy featuring a prominent central bar or bridge of stars that channels gas toward its core. Chandra X-rays (purple) highlight growing black holes along the bar and core, merged with Hubble optical light (white, yellow and soft blue) and JWST infrared dust filaments (red). Studying barred spirals in action can help reveal how gas in our own Milky Way, which is also a barred spiral, feeds its central black hole and forms new stars.
NGC 1672
A barred spiral galaxy featuring a prominent central bar or bridge of stars that channels gas toward its core. Chandra X-rays (purple) highlight growing black holes along the bar and core, merged with Hubble optical light (white, yellow and soft blue) and JWST infrared dust filaments (red). Studying barred spirals in action can help reveal how gas in our own Milky Way, which is also a barred spiral, feeds its central black hole and forms new stars.
X-ray: NASA/CXC/SAO; Optical: NASA/ESA/STScI/Hubble Heritage Team; Infrared: NASA/ESA/CSA/STScI/J. Lee and T. Williams; Image Processing: NASA/CXC/SAO/L. Frattare, J. Major, K. Arcand
A chaotic, dust-shrouded system of merging galaxies forming stars at a furious rate. Chandra X-ray data (magenta) pinpoint powerful black hole activity and hot gas, while Hubble optical (blue and white) and Webb infrared (red and grey) data illuminate vast stellar nurseries hidden behind interstellar dust. Systems like II Zw 096 show us how powerful galaxy collisions shaped the early universe.
II Zw 096
A chaotic, dust-shrouded system of merging galaxies forming stars at a furious rate. Chandra X-ray data (magenta) pinpoint powerful black hole activity and hot gas, while Hubble optical (blue and white) and Webb infrared (red and grey) data illuminate vast stellar nurseries hidden behind interstellar dust. Systems like II Zw 096 show us how powerful galaxy collisions shaped the early universe.
X-ray: NASA/CXC/SAO; Optical: NASA/ESA/STScI; Infrared: NASA/ESA/CSA/STScI; Image Processing: NASA/CXC/SAO/L. Frattare and J. Major
A nearby, face-on spiral galaxy whose clear spiral arms offer an unhindered view of its stellar engine. X-ray data from Chandra (purple) highlights point sources like neutron stars and stellar-mass black holes pulling material off companion stars (systems called X-ray binaries), while optical data from the Very Large Telescope’s MUSE instrument (pink and grey) maps glowing pockets of hydrogen gas. Ultraviolet data from NASA’s Swift telescope (blue) reveals populations of young, massive stars sizzling across the spiral arms. M33’s proximity to us allows astronomers to audit individual high-energy objects and map how stellar feedback affects a galaxy's ecosystem.
M33
A nearby, face-on spiral galaxy whose clear spiral arms offer an unhindered view of its stellar engine. X-ray data from Chandra (purple) highlights point sources like neutron stars and stellar-mass black holes pulling material off companion stars (systems called X-ray binaries), while optical data from the Very Large Telescope’s MUSE instrument (pink and grey) maps glowing pockets of hydrogen gas. Ultraviolet data from NASA’s Swift telescope (blue) reveals populations of young, massive stars sizzling across the spiral arms. M33’s proximity to us allows astronomers to audit individual high-energy objects and map how stellar feedback affects a galaxy’s ecosystem.
X-ray: NASA/CXC/SAO; Optical: ESO/VLT; UV: NASA/Swift; Image Processing: NASA/CXC/SAO/L. Frattare
A spiral galaxy famous for having two extra,
NGC 4258
A spiral galaxy famous for having two extra, “anomalous” spiral arms composed of hot gas. Chandra’s X-rays (royal blue) show superheated shockwaves created by central black hole jets, combined with optical light from Hubble (red, yellow and pale blue) and infrared dust filaments from Webb (bright orange). M106 helps show how supermassive black holes can create structural features that mimic star-bearing spiral arms, influencing a galaxy’s evolution.
X-ray: NASA/CXC/SAO; Optical: NASA/ESA/STScI; Infrared: NASA/ESA/CSA/STScI; Image Processing: NASA/CXC/SAO/L. Frattare
A compact dwarf irregular galaxy undergoing a violent, compact burst of star formation. Chandra and XMM-Newton observations (blue and purple) reveal massive bubbles of million-degree gas inflated by stellar winds, set against a backdrop of optical light (magenta, orange and white) imaged by Adam Block. Dwarf starburst galaxies can serve as local laboratories for studying the conditions of the early universe, where small, primitive galaxies formed stars at frantic rates.
NGC 1569
A compact dwarf irregular galaxy undergoing a violent, compact burst of star formation. Chandra and XMM-Newton observations (blue and purple) reveal massive bubbles of million-degree gas inflated by stellar winds, set against a backdrop of optical light (magenta, orange and white) imaged by Adam Block. Dwarf starburst galaxies can serve as local laboratories for studying the conditions of the early universe, where small, primitive galaxies formed stars at frantic rates.
X-ray: (XMM):ESA/XMM-Newton, (Chandra): NASA/CXC/SAO; Optical: Univ.of Arizona/Mt Lemmon SkyCenter/Adam Block/Josep Drudis; Image Processing: NASA?CXC/SAO/L. Frattare
A large spiral galaxy that is being stripped of its gas as it plunges at high speed through hot gas in the Virgo Cluster of galaxies. Chandra’s X-ray data (magenta) pinpoints high-energy point sources—such as X-ray binaries and supernova remnants—and diffuse hot gas nestled within the spiral disk imaged by Hubble (blue, brown and gold). A ground-based optical light image taken from New Mexico by Timothy Martin reveals red filaments of hydrogen gas streaming over 300,000 light-years behind the galaxy as it falls into the Virgo Cluster.
M90
A large spiral galaxy that is being stripped of its gas as it plunges at high speed through hot gas in the Virgo Cluster of galaxies. Chandra’s X-ray data (magenta) pinpoints high-energy point sources—such as X-ray binaries and supernova remnants—and diffuse hot gas nestled within the spiral disk imaged by Hubble (blue, brown and gold). A ground-based optical light image taken from New Mexico by Timothy Martin reveals red filaments of hydrogen gas streaming over 300,000 light-years behind the galaxy as it falls into the Virgo Cluster.
X-ray: NASA/CXC/SAO; Optical: NASA/ESA/D. Thilker/J. Lee/PHANGS-HST Team; Full-field: Tim Martin; Image Processing: NASA/CXC/SAO/L. Frattare
A giant elliptical galaxy undergoing a dusty merger, featuring a powerful jet of particles blasting tens of thousands of light-years into space. Chandra’s X-rays (blue) showcase the high-energy jet, with additional X-rays from IXPE (orange), while Webb infrared (magenta) and optical light (amber and white) from the European Southern Observatory expose a dark, churning dust lane. As one of the closest active galaxies to Earth, Cen A allows astronomers to study the effects of supermassive black hole jets in extraordinary detail.
Centaurus A
A giant elliptical galaxy undergoing a dusty merger, featuring a powerful jet of particles blasting tens of thousands of light-years into space. Chandra’s X-rays (blue) showcase the high-energy jet, with additional X-rays from IXPE (orange), while Webb infrared (magenta) and optical light (amber and white) from the European Southern Observatory expose a dark, churning dust lane. As one of the closest active galaxies to Earth, Cen A allows astronomers to study the effects of supermassive black hole jets in extraordinary detail.
X-ray: (Chandra) NASA/CXC/SAO, X-ray (IXPE): NASA/MSFC; Optical: ESO; Infrared: NASA/ESA/CSA/STScI; Image Processing: NASA/CXC/SAO/L. Frattare, K. Arcand, and J. Major
Famous for its broad central bulge and dark outer dust ring, this galaxy sits at a nearly edge-on tilt to Earth. Chandra X-rays (cyan and orange) isolate compact point sources and hot gas in the galaxy's sprawling halo, merged with Hubble optical light (warm white) and Webb infrared vision (purple-red dust lane). Studying M104 may help bridge the gap between spirals and ellipticals, helping astronomers better understand how a galaxy's giant outer cloud of stars grows and ages alongside its inner disk.
M104
Famous for its broad central bulge and dark outer dust ring, this galaxy sits at a nearly edge-on tilt to Earth. Chandra X-rays (cyan and orange) isolate compact point sources and hot gas in the galaxy’s sprawling halo, merged with Hubble optical light (warm white) and Webb infrared vision (purple-red dust lane). Studying M104 may help bridge the gap between spirals and ellipticals, helping astronomers better understand how a galaxy’s giant outer cloud of stars grows and ages alongside its inner disk.
X-ray: NASA/CXC/SAO; Optical:NASA/Hubble Heritage Team/AURA/STScI; Infrared: NASA/ESA/CSA/STScI; Image Processing: NASA/CXC/SAO/L. Frattare
This ring galaxy system formed when a smaller companion galaxy punched straight through its center like a bullseye, creating a powerful cosmic shockwave. Chandra X-rays (purple) uncover bright X-ray binary systems scattered along the collision shock wave, laid over Hubble’s optical image (blue and white) of expanding stellar rings. Such head-on collisions can trigger vast ripple effects, sparking huge waves of star birth across entire galaxies.
Arp 143
This ring galaxy system formed when a smaller companion galaxy punched straight through its center like a bullseye, creating a powerful cosmic shockwave. Chandra X-rays (purple) uncover bright X-ray binary systems scattered along the collision shock wave, laid over Hubble’s optical image (blue and white) of expanding stellar rings. Such head-on collisions can trigger vast ripple effects, sparking huge waves of star birth across entire galaxies.
X-ray: NASA/CXC/SAO; Optical: NASA/ESA/STScI/J. Dalcanton; Image Processing: NASA/CXC/SAO/L. Frattare
A
NGC 4725
A “one-armed” barred spiral galaxy surrounded by a prominent star-forming ring. Chandra’s X-ray data (magenta) pinpoints several bright X-ray sources, likely caused by growing black holes, embedded within the sweeping optical disk (soft blue and white) captured with the Mt. Lemmon Observatory. Galaxies with unusual single arms can offer a window into how the gravity from a passing galaxy can trigger bursts of star formation.
X-ray: NASA/CXC/SAO; Optical: NASA/ESA/STScI/NAOJ/R. Gendler; Image Processing: NASA/CXC/SAO/L. Frattare
A barred spiral galaxy packed with regions where stars are actively forming. Chandra X-ray data (magenta) highlights stellar nurseries and X-ray binaries scattered along dusty spiral structures brought to life by Hubble optical (white and grey) and Webb infrared (orange and red) observations. Comparing multiwavelength data of barred spirals containing active star formation helps scientists map how local starbursts build up galactic mass over time.
NGC 1385
A barred spiral galaxy packed with regions where stars are actively forming. Chandra X-ray data (magenta) highlights stellar nurseries and X-ray binaries scattered along dusty spiral structures brought to life by Hubble optical (white and grey) and Webb infrared (orange and red) observations. Comparing multiwavelength data of barred spirals containing active star formation helps scientists map how local starbursts build up galactic mass over time.
X-ray: NASA/CXC/SAO; Optical: NASA/ESA/STScI; Infrared: NASA/ESA/CSA/STScI; Image Processing: NASA/CXC/SAO/L. Frattare
A rare
NGC 660
A rare “polar ring” galaxy where a tilted outer ring of stars and dust rotates over the galaxy’s poles, an unusual structure likely caused by a collision with another galaxy about a billion years ago. Chandra’s X-rays (purple) reveal a possible growing supermassive black hole in the center of the galaxy, plus X-ray binaries nestled within the stars and dust captured by the Gemini Observatory in optical light (gold, blue and white). Studying polar rings teaches us about the diverse effects of stellar collisions on the shapes of galaxies.
X-ray: NASA/CXC/SAO; Optical:NSF/International Gemini Observatory/AURA; Image Processing: NASA/CXC/SAO/L. Frattare
An irregular galaxy undergoing intense star formation because of a gravitational interaction with a neighboring galaxy hundreds of millions of years ago. Chandra X-rays (blue), supplemented by NuSTAR data, show towering superwinds of million-degree gas blowing thousands of light-years out of the galactic disk, with Hubble optical light (yellow, orange and white) showing the galaxy shape, and Webb and Spitzer detailing infrared dust emission (red). M82 was nicknamed the Cigar Galaxy mostly because of its edge-on angle to Earth, which makes its central disk look like an elongated, cigar-shaped oval with small optical telescopes. The galaxy illustrates how violent galactic
M82
An irregular galaxy undergoing intense star formation because of a gravitational interaction with a neighboring galaxy hundreds of millions of years ago. Chandra X-rays (blue), supplemented by NuSTAR data, show towering superwinds of million-degree gas blowing thousands of light-years out of the galactic disk, with Hubble optical light (yellow, orange and white) showing the galaxy shape, and Webb and Spitzer detailing infrared dust emission (red). M82 was nicknamed the Cigar Galaxy mostly because of its edge-on angle to Earth, which makes its central disk look like an elongated, cigar-shaped oval with small optical telescopes. The galaxy illustrates how violent galactic “exhaust systems” can regulate a galaxy’s growth by venting gas outwards.
X-ray: NASA/CXC/SAO; Optical: NASA/ESA/STScI; Infrared: NASA/ESA/CSA/STScI; Image Processing: NASA/CXC/SAO/L. Frattare, J. Major, and K. Arcand
A pair of colliding, gas-rich spiral galaxies merging into a single massive system. Chandra’s X-ray data (pink) isolates point sources and shock-heated gas, Hubble’s optical light (blue and white) captures tidal tails of stars, and Webb’s infrared vision (red and orange) cuts through the dust to show hidden star formation. Galaxy collisions like this offer a preview of our far future, showing what might happen if our own Milky Way collides and merges with the nearby Andromeda Galaxy.
NGC 3256
A pair of colliding, gas-rich spiral galaxies merging into a single massive system. Chandra’s X-ray data (pink) isolates point sources and shock-heated gas, Hubble’s optical light (blue and white) captures tidal tails of stars, and Webb’s infrared vision (red and orange) cuts through the dust to show hidden star formation. Galaxy collisions like this offer a preview of our far future, showing what might happen if our own Milky Way collides and merges with the nearby Andromeda Galaxy.
X-ray: NASA/CXC/SAO; Optical: NASA/ESA/STScI; Infrared: NASA/ESA/CSA/STScI; Image Processing: NASA/CXC/SAO/L. Frattare
A face-on spiral galaxy whose orientation gives us an unobstructed view of its disk. X-ray emissions from Chandra (magenta) detail energetic X-ray binaries and supernova remnants scattered across dust lanes in an optical image (white, blue and gold) from Adam Block with Mt. Lemmon Observatory. Face-on orientations are important for galactic studies because they provide the most unobstructed views of a galaxy’s stars and gas.
NGC 3938
A face-on spiral galaxy whose orientation gives us an unobstructed view of its disk. X-ray emissions from Chandra (magenta) detail energetic X-ray binaries and supernova remnants scattered across dust lanes in an optical image (white, blue and gold) from Adam Block with Mt. Lemmon Observatory. Face-on orientations are important for galactic studies because they provide the most unobstructed views of a galaxy’s stars and gas.
X-ray: NASA/CXC/SAO; Optical: Adam Block/Mount Lemmon SkyCenter/University of Arizona; Image Processing: NASA/CXC/SAO/L. Frattare
A spiral galaxy viewed from its side, featuring a giant halo of hot gas blowing out of its stellar disk. X-rays from Chandra and ESA’s XMM-Newton (purple and royal blue) trace hot gas driven out by supernovas and black holes and neutron stars pulling gas from their companions, while optical light (light blue, gold and white) from ground-based observer R. Jay GaBany showcases dense dust lanes. Edge-on views of galaxies allow astronomers to study how flat their stellar disks are and provide the clearest views of material located above or below the disk.
NGC 4631
A spiral galaxy viewed from its side, featuring a giant halo of hot gas blowing out of its stellar disk. X-rays from Chandra and ESA’s XMM-Newton (purple and royal blue) trace hot gas driven out by supernovas and black holes and neutron stars pulling gas from their companions, while optical light (light blue, gold and white) from ground-based observer R. Jay GaBany showcases dense dust lanes. Edge-on views of galaxies allow astronomers to study how flat their stellar disks are and provide the clearest views of material located above or below the disk.
X-ray: NASA/CXC/SAO; Optical: ©2011-2015 by R Jay GaBany, Cosmotography.com; Image Processing: NASA/CXC/SAO/L. Frattare

X-rays are critical for the study of galaxies, revealing unique and important information about these cosmic building blocks. For example, Chandra exposes gas that has been superheated to millions of degrees by winds from massive stars, the outflows from supermassive black holes, and the debris from exploded stars. These are key sources of elements in our bodies, in the air we breathe, and the planet we live on. Chandra also sees some of the hottest and most energetic galactic phenomena in the universe, forming a more complete picture of how galaxies live, interact, and evolve when combined with data from other types of light and telescopes.

Spiral and star-forming engines

Face-on spiral galaxies like Messier 33 and NGC 3938 offer unobstructed views of places where energetic pairs of stars and cosmic explosions live along spiral arms. Barred spirals like NGC 1672 and NGC 1385 show how central bar-shaped collections of stars, gas, and dust funnel fuel inward to ignite bursts of star formation. NGC 4725 reveals how star formation can be triggered by a previous collision with another galaxy. Meanwhile, edge-on views of NGC 4631 (the Whale Galaxy) and the starburst Messier 82 (the Cigar Galaxy) showcase giant halos and superwinds of million-degree gas driven thousands of light-years into space by intense explosions of stars, enriching surrounding intergalactic space with vital elements.

Active galactic nuclei, black hole outflows

Powerful, growing black holes in the cores of their host galaxies, known as active galactic nuclei, send energy outward in outbursts and jets that impact entire galaxies. In Centaurus A, Chandra and IXPE data expose a high-energy particle jet blasting tens of thousands of light-years into space from its central engine. In Messier 106, jets from the supermassive black hole heat surrounding gas to create spiral arms that are different from those typically found in spiral galaxies. Meanwhile, the iconic Sombrero Galaxy (Messier 104) highlights a supermassive black hole embedded in a colossal stellar bulge, where Chandra’s X-rays map a diffuse halo of million-degree gas and hot stellar remnants surrounding its sweeping dust lanes.

Collisions, mergers, cosmic disruptions

The gallery also showcases galaxies undergoing extreme gravitational transformations. A direct impact in Arp 143 acts like a cosmic bullseye, creating an expanding ring galaxy and triggering waves of star birth. Violent mergers, such as NGC 3256 and the dust-shrouded starburst II Zw 096, reveal the kind of chaotic galaxy collisions that dominated the early universe and offer a preview of the Milky Way’s distant future merger with nearby galaxy Andromeda. NGC 1569 acts as a local laboratory for studying early universe starbursts, NGC 660 showcases a rare “polar ring” galaxy where a ring of stars orbits over its poles, and Messier 90 shows a spiral galaxy plowing through the Virgo Cluster, having its star-forming gas violently stripped away.

NASA’s Marshall Space Flight Center 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

To learn more about Chandra, visit

https://nasa.gov/chandra

About the Author

Megan Watzke

Hubble Solves Merger Mystery From Milky Way’s Early Years

✇NASA Breaking News
17 August 2026 at 11:00

5 min read

Hubble Solves Merger Mystery From Milky Way’s Early Years

An illustration of two galaxies in the midst of a collision against a dark, star-filled background. The collision takes up the middle third of the illustration. On the right, a larger galaxy is viewed at an angle from 11 ou2019clock to 4 ou2019clock, with a white-yellow core surrounded by mottled brown dust lanes and faint bluish spiral arms. To the left, a smaller, bright blue-white galaxy is stretched into a curved, hook-like shape as gravity distorts it. A broad, glowing bridge of pale blue gas and stars extends off the galaxy at the left, while wispy streams extend above and below the larger galaxy at the right. The words u201cArtistu2019s Conceptu201d appear in the lower left corner.
About 12 billion years ago, a dwarf galaxy known as LKH collided with a young Milky Way and merged with it. This artist’s concept portrays that collision. NASA’s Hubble Space Telescope uncovered definitive evidence of this collision by studying globular star clusters.
Illustration: NASA, ESA, Joseph Olmsted (STScI)

Our home galaxy, the Milky Way, grew to its current size in part by consuming smaller galaxies. Now, new data from NASA’s Hubble Space Telescope shows definitive evidence of a dwarf galaxy merging with the young Milky Way galaxy in the earliest phases of its evolution. This finding extends our knowledge of our galaxy’s history 1.8 billion years farther back in time than before.

The results published Monday in the journal Nature Astronomy.

The Milky Way today is a massive spiral galaxy home to hundreds of billions of stars. However, our galaxy wasn’t always so large; it has grown by forming new stars from its gas clouds as well as collecting stars, gas, and dark matter from other galaxies through mergers.

The most recent massive merger in our galaxy’s history took place with the Sagittarius dwarf galaxy, beginning over 6 billion years ago and still ongoing today. Looking back into the even more distant past, researchers learned that the Milky Way galaxy consumed another dwarf galaxy called Gaia-Sausage-Enceladus 10 billion years ago. This ancient merger greatly affected the structure of our galaxy’s disk of stars. Other, smaller mergers occurred between these two.

But our galaxy’s history doesn’t stop there. Both observations and simulations have suggested that another large merger preceded these two, though the specifics of the event have been heavily debated. Now, Hubble has uncovered definitive evidence of an earlier merger that occurred about 11.8 billion years ago, or just 2 billion years after the big bang.

“Our home is the Milky Way galaxy, but we do not know how our house was built,” said Davide Massari, lead author, Astrophysics and Space Science Observatory of Bologna in Italy. “In this paper we discover where the first significant batch of bricks came from: a dwarf galaxy that we call LKH.”

Cosmic archaeological sites

Immense astronomical surveys and precision data from spacecraft like ESA’s (European Space Agency’s) Gaia mission have been instrumental in piecing together the history of our galaxy. The farther back into our galaxy’s history that scientists attempt to look, the more difficult it becomes to tell what happened. When our galaxy was young, it was smaller and much closer in size to the galaxies it clashed with. It was also more chaotic, and it’s possible that the signs of mergers have been erased over billions of years.

It’s into this murky past that Hubble peered. Researchers used Hubble to study some of the Milky Way galaxy’s globular clusters: immense, roughly spherical collections of tens of thousands to a few million stars. Globular clusters contain some of the oldest stars in our galaxy, and they can act as cosmic archaeological sites that preserve stars from other galaxies the Milky Way galaxy has collected.

“Thanks to the high resolution and depth of Hubble imaging, we could measure the age and the metal content of these clusters with unprecedented precision,” said Chiara Zerbinati, study co-author, University of Bologna in Italy. “Coupled with measurements from Gaia, this made it possible to distinguish a population of globular clusters that are different from the others. These are the clusters that were born in LKH, and they tell us when that galaxy was devoured by ours, and how massive it was.”

The team analyzed Hubble observations of 39 globular clusters in the inner 20,000 light-years of our galaxy, where evidence of the most ancient mergers should be preserved. They expected this sample to contain globular clusters that formed within the young Milky Way galaxy as well as those collected from the Gaia-Sausage-Enceladus dwarf galaxy about 10 billion years ago.

Using Hubble’s sensitive observations to determine each cluster’s precise age and associated metallicity — the abundance of elements heavier than helium — they determined there was a third population of globular clusters in the inner regions of our galaxy. The team found that these clusters are older than the group collected in the Gaia-Sausage-Enceladus merger, but younger than those born in the Milky Way, regardless of their metal content. These  clusters, therefore, came from a separate and even earlier merger — in which the Milky Way galaxy absorbed a dwarf galaxy containing roughly 500 million times the mass of the Sun in stars, a significant fraction of our galaxy’s mass at the time. They named this dwarf galaxy Low-energy-Kraken-Heracles, or LKH, in honor of three earlier research papers that championed the idea of a merger early in our galaxy’s history.

Such a large merger so early in the Milky Way galaxy’s formation has profound implications for the evolution of our galaxy.

“Some past studies have argued that the earliest phases of our galaxy’s evolution were defined by stars born only in our galaxy,” says Massari. “Here, we have shown that stars born in external galaxies also need to be considered.”

The team plans to continue their work to unravel the history of the Milky Way galaxy by studying its globular clusters, aiming to characterize all the massive mergers that our galaxy has experienced across cosmic history.

“Hubble is observing globular clusters that have never been studied before, and this will help us characterize the merger events that are far back in time in the Milky Way galaxy’s history,” said Fernando Aguado-Agelet, co-author, University of Vigo and the University of La Laguna in Spain.

The Hubble Space Telescope has been operating for more than three decades and continues to make ground-breaking discoveries that shape our fundamental understanding of the universe. Hubble is a project of international cooperation between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope and mission operations. Lockheed Martin Space also supports mission operations at Goddard. The Space Telescope Science Institute in Baltimore, which is operated by the Association of Universities for Research in Astronomy, conducts Hubble science operations for NASA.

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Related Images & Videos

An illustration of two galaxies in the midst of a collision against a dark, star-filled background. The collision takes up the middle third of the illustration. On the right, a larger galaxy is viewed at an angle from 11 ou2019clock to 4 ou2019clock, with a white-yellow core surrounded by mottled brown dust lanes and faint bluish spiral arms. To the left, a smaller, bright blue-white galaxy is stretched into a curved, hook-like shape as gravity distorts it. A broad, glowing bridge of pale blue gas and stars extends off the galaxy at the left, while wispy streams extend above and below the larger galaxy at the right. The words u201cArtistu2019s Conceptu201d appear in the lower left corner.

LKH Milky Way Merger Illustration

About 12 billion years ago, a dwarf galaxy known as LKH collided with a young Milky Way and merged with it. This artist’s concept portrays that collision. NASA’s Hubble Space Telescope uncovered definitive evidence of this collision by studying globular star clusters.

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Details

Last Updated
Aug 18, 2026
Editor
Andrea Gianopoulos
Contact
Media

Claire Andreoli
NASA’s Goddard Space Flight Center
Greenbelt, Maryland
claire.andreoli@nasa.gov

Bethany Downer
ESA/Hubble
Baltimore, US

Christine Pulliam
Space Telescope Science Institute
Baltimore, Maryland

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