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Hubble Telescope sees spectacular 'superbubble' | Space photo of the day for Sept. 4, 2026

About 160,000 light-years away lies one of our Milky Way's little galactic neighbors: The Large Magellanic Cloud (LMC). And thanks to a new observing program, the Hubble Space Telescope has provided us with an intricate image of a nebula in the LMC. The surprising part? There's a giant void at the center. Scientists call it a "superbubble."
What is it?
What you're seeing in this image is a nebula within the LMC known as LHA 120-N44, or simply N44. It's located in the constellation of Dorado and, like a classic nebula, is the site of stars being born at a noticeably rapid rate.
But of course, what really can't be missed is the huge hole at the center of N44's dusty tendrils — this is the "superbubble," and its dimensions are staggering. NASA says it's about 210 by 140 light-years across — a truly unimaginable size, considering the distance between our sun and Pluto isn't even a single light-year.
One light-year, the distance light travels in a year, is about 6 trillion miles (9.7 trillion kilometers).
Why is it noteworthy?
The superbubble is a bit of a mystery, but one theory of why it exists is that stars at the center of the bubble could have undergone supernova explosions or have released stellar winds that swept away gas in the nebula. This could have resulted in a "void," as NASA calls it, surrounded by a gaseous shell. That would explain away the image we see pretty well, but there will likely be studies dedicated to refining that story.
Of note, in that shell around the superbubble, stars continue to form and show themselves as beautiful little specks across the watercolor-like landscape.
Something else interesting about this image is that N44 is what's known as an "emission nebula," meaning the gas you see has been energized by stars in the area. This enhances the luminescent quality of the portrait.
This is because the energization process, or ionization to be specific, generates ionized gas that ultimately must cool down. During that cooling, it goes from a higher energy state to a lower energy state and thus releases some energy. This energy loss causes N44 to glow brightly, creating the beautiful scene we see.
The reason scientists have used the Hubble Space Telescope to study N44 is this particular nebula offers good conditions to study star formation and evolution. As a matter of fact, Hubble managed to survey nearly half a million stars in and around the cluster, 30,000 of which are in the very early stages of their lives.
N44 has been a major topic of interest for quite some time. For instance, it made headlines in 2021 as well as in 2012 — both times due to Hubble's eye yet again — and observations with the Chandra X-ray Observatory led to a 2011 paper that discusses supernova shock waves and other phenomena shaping the nebula and its cavity.
- The Debrief
- NASA’s Two Most Powerful Space Telescopes Will Share the Same Region of Space. Here’s Why That’s Not a Problem
NASA’s Two Most Powerful Space Telescopes Will Share the Same Region of Space. Here’s Why That’s Not a Problem
When NASA announced that the new Nancy Grace Roman Space Telescope will perform its science duties from a point in space known as Lagrange 2, many observers noted that the space agency’s current state-of-the-art space observatory, the James Webb Space Telescope, shares this same orbital location.
Due to the extremely sensitive nature of both satellites and their sensors, and the irreplaceable scientific value they will provide in the future, it might seem natural to wonder whether these two space observatories are at risk of a deep-space collision.
Fortunately, that’s a very unlikely prospect, and here’s a look at all the space separating Roman and Webb—and how NASA will ensure the two observatories remain safely apart.
Nancy Grace Roman Space Telescope Heading for Lagrange 2
Many scientific satellites reside a little over 200 miles above Earth in an orbital plane called Low Earth Orbit (LEO). This proximity enables communication with Earth and offers the potential for future servicing missions.
For example, NASA’s groundbreaking Hubble Space Telescope orbits LEO at about 300 miles above Earth. This proximity enabled servicing missions that have kept Hubble delivering valuable scientific data for over three and a half decades since its 1990 launch. Still, LEO also limits which missions Hubble can undertake.
More recently, NASA launched JWST. However, unlike Hubble, Webb rocketed roughly one million miles from Earth before arriving at Lagrange 2. According to a NASA fact sheet detailing the Roman Space Telescope’s mission, this location offers several benefits over LEO.
“At L2, the gravity of the Sun and Earth, together with an object’s motion around the Sun, let it stay lined up with Earth as they orbit,” NASA explains, “allowing Roman to have a relatively steady orbit without using much fuel.”
NASA also notes that heat from Earth, the Sun, and the Moon has less impact on infrared telescopes designed to “see” heat. L2 also offers JWST and Roman, “a constant, unobstructed view of a wide swath of the sky.”
“Earth won’t block much of Roman’s view since it will be so distant,” NASA explains.
Is There a Danger of a Roman-JWST Collision?
Instead of sitting still at the heart of L2, NASA notes that Webb “traces out a large orbit around the actual L2 point.” For comparison, the space agency noted that JWST’s orbit around L2 is “much larger than the Moon’s orbit around Earth.”
Like Webb, the Nancy Grace Roman Space Telescope is also destined for L2. The new space telescope will also trace out an orbit around L2 rather than remaining comparatively stationary.
Because of the wide orbits of both spacecraft and the efforts of the mission’s controllers, NASA said the two valuable space telescopes “will easily be kept far apart.”
Five-Year Mission Could Stretch to Ten or Beyond with Refueling
Like previous NASA missions, Roman will have a primary lifetime and a backup plan if the observatory remains viable after the first mission ends. For Roman, both the primary and secondary missions are slated for five years, bringing the observatory’s planned potential lifetime up to a possible ten years.
Notably, several NASA missions have continued to deliver scientific data well beyond their planned primary and secondary missions. Perhaps the most famous example is Voyager 1. Launched in 1977, the interplanetary mission has since left the solar system and continues to return data from beyond the heliopause, an area of deep space over 14 billion miles from Earth.
When discussing what obstacles may result in a shorter mission profile, NASA said that “fuel is expected to be the mission’s life-limiting resource.”
“While NASA does not currently have an ability to service observatories at L2, Roman is designed to be refuellable,” they added.
Christopher Plain is a Science Fiction and Fantasy novelist and has spent the last six years as Associate News Editor and Head Science Writer at The Debrief. Follow and connect with him on X, learn about his books at plainfiction.com, or email him at christopher@thedebrief.org.
- The Debrief
- The Nancy Grace Roman Space Telescope Launches Tomorrow—Here’s a Look at the High-Tech Instruments On Board
The Nancy Grace Roman Space Telescope Launches Tomorrow—Here’s a Look at the High-Tech Instruments On Board
Before NASA’s Nancy Grace Roman Space Telescope arrives at its Lagrange 2 destination and begins performing years of observations, the cutting-edge observatory that started life as a National Reconnaissance Office (NRO) spy satellite will deploy and calibrate its suite of instruments.
These include a primary mirror, a Wide Field Array sensor, and a Coronograph Instrument technology demonstration designed to block out starlight to enable direct imaging of exoplanets.
Here is a quick peek at those instruments, which will help Roman image exoplanets, search for signs of dark matter and dark energy, and add huge amounts of raw scientific data that will keep scientists busy for years to come.
Nancy Grace Roman Space Telescope Instruments: The Primary Mirror
Designed and built at L3Harris Technologies in Rochester, New York. Roman’s primary is 7.9 feet across (2.4 meters). That is the same size as the one on NASA’s legacy Hubble Space Telescope.
However, NASA said Roman’s main mirror, which weighs 410 pounds (186 kilograms), is just one-fourth the weight of Hubble’s, “thanks to major improvements in technology.” They also noted that the weight difference was critical to the Lagrange Point 2 mission’s viability.
The Wide Field Instrument
While the main mirror will gather light, Roman’s Wide Field Instrument, or WFI, will gather digital images of the cosmos. According to NASA’s mission fact sheet, the 300-megapixel infrared camera “will give Roman the same 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 bigger than the apparent size of a full moon,” the space agency explained.

Unlike many telescopes designed to focus incoming light toward a central point, NASA said Roman is designed to “see the most detail in a ring around the center.” That’s because the WFI’s millions of detectors are laid out in an arch shape. The space agency said this design “helps Roman capture a much wider area with equally sharp imaging and also lets both instruments operate simultaneously.”
Due to the hardware and software improvements, NASA said the WFI will gather data “up to 1,000 times faster than Hubble. When Roman’s five-year mission is completed, mission planners said they expect to gather “up to 20,000 terabytes (20 petabytes)” of data.
“Its sweeping cosmic surveys will help scientists discover new information about planets beyond our solar system, untangle mysteries like dark energy, and map how matter is structured and distributed throughout the cosmos,” the agency said when detailing WFI’s capabilities, adding that the mission’s “broad, crisp view will produce an extraordinary resource for a wide range of additional investigations.”
WFI’s Detectors
In a fact sheet, NASA said that the detector array at the heart of Roman’s WFI contains 18 “saltine cracker-sized” detectors. The space agency also said that each detector contains roughly 16.8 million tiny pixels (for a total of 300 million), “providing the mission with exquisite image resolution.”
Each cutting-edge detector comprises millions of photodiodes, which convert light into electrical current. NASA said this number of detectors, made from mercury-cadmium-telluride photodiodes (sensors that convert light into an electrical current), provides “one for each pixel.”
The space agency also noted that individual detectors are secured to a silicon electronics board that will help process the light signals using indium. Unlike steel, indium is a soft metal that has roughly the same consistency as chewing gum.
When they are working together, NASA said that these ultra-sensitive detectors “can capture vast areas of sky in a single shot while still revealing incredibly fine detail, allowing Roman to map the cosmos faster and more precisely than ever before.”
The Experimental Coronagraph
Astronomers typically infer the existence of exoplanets by the gravitational effects they exert on their host star or the dimming of the star’s light. However, directly imaging exoplanets has remained challenging because the star’s extremely bright light dwarfs the much dimmer light reflected by the planet. As a result, only a few of the largest, young “super Jupiters” have been directly imaged to date.

To block enough of a star’s light to capture an image of an exoplanet, Roman’s engineers have installed a novel Coronagraph. NASA describes this experimental device as “a system of optics, masks, self-flexing mirrors, and sensors designed to demonstrate the most advanced technologies ever flown in space for directly imaging planets around other stars.”
After its mid-flight deployment, Roman’s Coronagraph team will begin conducting a series of pre-planned observations. Mission planners said these observations “are scheduled for a total of three months spread across the mission’s first year-and-a-half of operations.”
“The Coronagraph aims to photograph worlds and dusty disks around nearby stars in visible light to help us see giant worlds that are older, colder, and in closer orbits than the hot, young super-Jupiters direct imaging has mainly revealed so far,” the space agency explained.
The Roman team expects to release new images by early 2027. For detailed updates, follow the
Roman blog at science.nasa.gov/blogs/roman.
Christopher Plain is a Science Fiction and Fantasy novelist and has spent the last six years as Associate News Editor and Head Science Writer at The Debrief. Follow and connect with him on X, learn about his books at plainfiction.com, or email him at christopher@thedebrief.org.
Hubble captures a corner of M20
Life in space is hard. Most orbiting observatories retire well before their 20th birthday. Yet the Hubble Space Telescope has survived and continues to thrive well into its 30s. Astronomers celebrated the observatory’s 36th birthday in April by releasing a new image of the Trifid Nebula (M20). This stellar nursery lies about 5,000 light-years fromContinue reading "Hubble captures a corner of M20"
The post Hubble captures a corner of M20 appeared first on Astronomy Magazine.
Lego deploys Hubble Space Telescope as detailed desktop model
For 35 years, the Hubble Space Telescope has looked out into the Universe. Now, Lego is inviting builders to look inward with its latest model of the orbiting observatory.
The new Lego Icons Hubble Space Telescope (set no. 11382) was released on August 1 for $140 at the toy company's stores and its online shop. The 1,252-piece kit builds a 15-inch-long (38-cm) desktop model that is about twice as large as the previously released Lego Hubble models.
The Icons Hubble is the first to be sized in comparison to a Lego minifigure, such that the included astronaut provides a sense of scale for the telescope.


© LEGO
NASA’s Hubble Shows Star Formation in Andromeda Galaxy Winding Down
NASA’s Hubble Shows Star Formation in Andromeda Galaxy Winding Down

Image: NASA, ESA, Benjamin Williams (UWashington), Zhuo Chen (UWashington), L. Clifton Johnson (Northwestern); Image Processing: Joseph DePasquale (STScI)
A new study using data from NASA’s Hubble Space Telescope finds that star formation in the nearby Andromeda galaxy has undergone a 500-million-year decline, with an even steeper drop in the last 40 million years. Andromeda, a spiral galaxy comparable in size to our Milky Way, is close enough to be seen with the unaided eye from areas with dark skies. Located about 2.5 million light-years from Earth, practically our cosmic backyard, Andromeda offers an opportunity for astronomers to examine its stellar populations in detail, leading to better understanding of the past of galaxies like our own.
The results published Monday in The Astrophysical Journal.
To reach this conclusion, the researchers combined data from two Hubble surveys: the Panchromatic Hubble Andromeda Treasury and the Panchromatic Hubble Andromeda Southern Treasury. Together, these two surveys mapped two-thirds of the disk of Andromeda in ultra-sharp detail. In total, the team measured about 200 million individual stars across the galaxy, giving them a detailed picture of Andromeda’s past activity.
“We need to measure the individual stars because they are the fossil record of the galaxy’s formation. Hubble is the only telescope that can give you high enough spatial resolution over a large enough area to be able to do that in Andromeda,” said Ben Williams, astronomer at the University of Washington and a co-author on the study.
Massive stars are bluer and short-lived, while less massive stars are redder and longer-lived. As a result, areas that have experienced recent star formation tend to have a larger fraction of blue stars, while areas with less recent star formation typically have a redder population. The team divided the Andromeda images into thousands of squares, spanning 300 light-years on each side of the square, and determined the history of star formation within each parcel to gain a comprehensive view of the galaxy’s past.
Steady decline
Previous research showed the Andromeda galaxy experienced a dramatic burst of star formation about 2 billion years ago, likely due to a past interaction or merger with another galaxy. Since that time, star formation has been steadily declining.
Astronomers measure the rate of star formation in terms of the mass, or amount of gas and dust, converted into stars per year. The researchers calculated that, 500 million years ago, Andromeda formed stars at a rate of about one solar mass per year. However, the formation rate dropped to about half that by 40 million years ago. The current rate has plummeted even farther, to about one-fifth the mass of our Sun per year.
The team also examined whether that decline was consistent across the galaxy or concentrated in certain areas. They found that much of the recent star formation has occurred in a star-forming ring located about 32,000 light-years from the galaxy’s center. As a result, much of the decline they measure is driven by decreasing activity within that ring.
Rather than being the result of reduced material from which new stars can form, the decline is more likely to be a natural winding down from its previous, more active state.
“It’s just like after running a marathon, sometimes you’ve got to take a bit of a breather,” said Tobin Wainer, lead author, University of Washington.
Likely suspect
The team also investigated whether there was any connection between the decrease of activity in Andromeda and its proximity to satellite galaxy M32 (Messier 32). The M32 galaxy is separated from Andromeda by about 16,000 light-years in the plane of the sky; however, its 3D location in space is uncertain. As a result, astronomers are unsure if or when it might have interacted with Andromeda in the past.
“One of the major motivations for this program was to probe potential interactions between M32 and Andromeda’s disk,” said Zhuo Chen, co-author, University of Washington.
Survey data from the Panchromatic Hubble Andromeda Southern Treasury allowed the team to study the history of star formation in Andromeda near M32. They found that this area showed signs of decreased star formation compared with other regions. The timing of this decrease, which this study finds began roughly 60 million years ago, could help constrain when the M32 galaxy interacted with Andromeda’s disk.
“We can’t explicitly say that we are seeing a decrease in star formation because of M32. But it’s right there, and it’s definitely the most likely suspect,” said Wainer.
The team plans to continue analyzing the Hubble data and combine it with data from ground-based observatories to gain additional insights into the history of Andromeda.
“There’s a strong scientific value to this archival data. Andromeda is important because it’s a neighbor that is close enough that we can see it in great detail while also getting a global perspective,” said Raja GuhaThakurta, co-author, University of California Santa Cruz.
An even greater global perspective is likely to come from NASA’s Nancy Grace Roman Space Telescope after it launches as early as Sunday, Aug. 30. Roman’s gigantic field of view can cover at least 100 times as much area as Hubble at near-infrared wavelengths in a single observation. A newly approved Roman observing program will image the entirety of Andromeda’s disk and areas of its surrounding halo, allowing astronomers to measure hundreds of millions of stars and enabling groundbreaking new science.
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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Claire Andreoli
NASA’s Goddard Space Flight Center
Greenbelt, Maryland
claire.andreoli@nasa.gov
Christine Pulliam
Space Telescope Science Institute
Baltimore, Maryland
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Discover More Topics From Hubble
Hubble Space Telescope
Since its 1990 launch, the Hubble Space Telescope has changed our fundamental understanding of the universe.

Hubble Science Highlights
Hubble’s most notable scientific discoveries reflect the broad range of research and the breakthroughs it has achieved.

Hubble Images
Explore Hubble’s iconic images of the universe, and view photos of mission operations and astronauts servicing Hubble in space.

Hubble News

Hubble Spies One-Sided Spiral
3 min read
Hubble Spies One-Sided Spiral
The subject of this NASA/ESA Hubble Space Telescope image is a spiral galaxy struggling against titanic forces that appear on galactic scales in space. This is NGC 4654, an intermediate spiral galaxy in the constellation Virgo (the Maiden). It is classified as an “intermediate” because its overall shape lies between spiral galaxies that have a bar across their centers and those that don’t. NGC 4654 has a weak bar structure at its center and is located 72 million light-years from Earth in the Virgo Cluster, a particularly massive and populous galaxy cluster.
NGC 4654 is particularly asymmetric, with a rounded and clearly-defined edge on one side and a long tail of gas stretching out from the opposite side — outside the field of view captured in this image. This gaseous tail is the result of ram pressure stripping, a force that galaxies can experience as they plow through space. NGC 4654 moves with such high velocity that it sweeps up and rams through the hot, rarefied gas filling the space between the Virgo Cluster’s galaxies. This intracluster medium in turn exerts a “ram pressure” on the galaxy, compressing the galaxy’s leading edge and dragging its gas behind the galaxy, creating the elongated tail.
It’s not just the galaxy’s gas that is unevenly distributed: its stars are too, and this is more unusual for a spiral galaxy. While the spiral arm on its leading edge is rich with stars and gas, the opposite arm noticeably lacks stars, influencing the galaxy’s lopsided spiral shape. Astronomers think that ram pressure alone is unlikely to cause this effect. Rather, NGC 4654 was also subjected to the gravitational force of fellow Virgo Cluster galaxy NGC 4639. While the two galaxies are far apart now, it’s thought that a fly-by interaction between them around 500 million years ago ripped away NGC 4654’s gas along one side, limiting star formation there and creating the asymmetry in its shape.
Many galaxies that undergo ram pressure stripping suffer reduced star formation rates as the cold gas that collapses to form their stars is pulled away and lost. NGC 4654, however, is still forming nearly two Suns’ worth of stars every year, a rate comparable to other galaxies of similar size. The active star formation is visible in the latest Hubble data included in this image. The data picks up on a wavelength of red light emitted by the clouds of energized gas where newborn stars lurk. The bright pink bubbles that appear across NGC 4654 — from its forward spiral arm, to around its weak bar, and out to the edge of its disk — are areas where these newborn stars shine.
The data used in this image came from two observing programs (#15654, #17502) that aim to link the gas in galaxies with star formation. By observing many prominent galaxies in the vicinity of our own, researchers hope to better understand how gas moves in galaxies, where and when it collapses to form stars and star clusters, and what effect those new stars have on the gas around them.
Text Credit: ESA/Hubble
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NASA’s Goddard Space Flight Center, Greenbelt, MD
claire.andreoli@nasa.gov
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Hubble Space Telescope
Since its 1990 launch, the Hubble Space Telescope has changed our fundamental understanding of the universe.

Hubble’s Galaxies
Explore an assortment of galaxies with Hubble.

Hubble Science Highlights
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Hubble Images
Explore Hubble’s iconic images of the universe, and view photos of mission operations and astronauts servicing Hubble in space.

- Space
- Hubble telescope watches unique nova explosion fire cosmic 'bullets' through the Milky Way at 20 million mph
Hubble telescope watches unique nova explosion fire cosmic 'bullets' through the Milky Way at 20 million mph
Using NASA's long-serving Hubble Space Telescope, astronomers have discovered that a stellar explosion in the Milky Way is blasting out cosmic bullets travelling at 20 million miles per hour.
The cosmic explosion in question is V445 Puppis, which erupted in 2000 and is the only known "helium nova" in our galaxy. Though astronomers have been studying V445 Puppis for two decades, much of the phenomena associated with it were shrouded in mystery due to a vast cloud of dusty debris that surrounded this nova.
When this debris finally cleared, a team of researchers was able to peer into V445 Puppis using Hubble, NASA's exoplanet-hunting spacecraft TESS (Transiting Exoplanet Survey Satellite), and the Earth-based Very Large Telescope (VLT), along with an array of other instruments. This allowed them to discover not only the "bullets", clumps of potentially oxygen-rich gas it is firing, but also the true nature of this system. This revealed that V445 Puppis consists of a dead star hungrily feeding on a companion star that is, by itself, a rare find. Thus, this system offers scientists a rare chance to study one of the rarest types of binary systems and one of the rarest cosmic explosions.
"The origin of these 'bullets' is a mystery. We suspect that these originated post-outburst, but 'bullets' of this kind have not been observed in any other nova," team member John Mills, a researcher at the University of Warwick in the UK, said in a statement.
What is a helium nova?
Helium novas like V445 Puppis occur when a white dwarf dead star cannibalistically strips helium-rich but hydrogen-poor matter from a star that has already lost its outer layer of hydrogen, exposing inner layers of helium; forming a rare "helium star." By contrast, "ordinary" novas are explosions triggered by the buildup of stolen stellar matter rich in hydrogen, not helium.
As the material accumulates on the surface of the white dwarf (a type of stellar remnant left behind when stars around the mass of the sun die) it creates runaway pressures and temperatures that eventually trigger a thermonuclear explosion.
When V445 Puppis went nova back in late 2000, it launched vast, twin plumes of debris that resemble butterfly wings. Stretching out for more than a trillion miles, astronomers initially spotted this bipolar outflow in infrared. The nova also spawned a thick disc of dust that completely obscured the binary star system. That cloud persisted for over two decades, preventing astronomers who were investigating the expanding debris from determining what kind of stars the blast originated from.
Once the debris cleared, this team determined that the system contained a helium star, one of only a few thousand of these stripped stellar bodies to be discovered among the billions of stars that populate the Milky Way.
"The culprits behind this galactic eruption have been an enduring mystery over the past 25 years, which is why it is very exciting to confirm that this helium nova was the result of a helium star accreting onto a white dwarf," Mills said.
The findings also revealed cosmic "bullets" that are even more remarkable, as they have never been seen around any other novas. Intriguingly, the team also found that V445 Puppis may be about to go nova again, and this could lead to an entirely different type of cosmic explosion.
Is V445 Puppis about to blow its top again?
Mills found that the white dwarf in V445 Puppis has overcome its stellar indigestion and is once again feeding on its companion helium star.
This is the process that led to the initial helium nova, and could mean that another episode of this rare type of cosmic explosion is soon to occur.
That has implications for our understanding of another type of cosmic eruption, this time a type of supernova called a Type Ia supernova. These occur when white dwarfs overfeed on companions and are completely destroyed by the resultant explosion.
Scientists have long suspected that repeated helium nova eruptions could lead to final Type Ia supernovas.

A new Type Ia supernova would be exciting because these events are so regular in terms of their light emission that they can be used as so-called "standard candles" to measure cosmic distances and gauge the age of the universe.
This means that they can also be employed in the quest to understand how fast the universe's expansion is proceeding, and the influence of the mysterious force called dark energy on this process.
"I look forward to seeing how this result may help us uncover what powers other similar hydrogen-poor astronomical explosions, such as the famous Type Ia supernovas," Mills said.
The team's research was presented this week at the Royal Astronomical Society's National Astronomy Meeting in Birmingham, UK.
Hubble Space Telescope images galaxy scientists thought was impossible to find
A bright, dense cluster of hot, massive stars in a galaxy that existed 1.4 billion years after the big bang has been found helping to end the early universe's foggy days during which neutral hydrogen gas was draped across the cosmos, obscuring ultraviolet light from luminous objects.
The cluster was found emitting ultraviolet light in a small but quickly growing galaxy by the Hubble Space Telescope. The presence of this ultraviolet light, and the star-forming history of the cluster producing it, suggests that bursts of star formation contributed to waves of ionizing radiation that gradually cleared out the opaque neutral hydrogen.
In the aftermath of the big bang, the universe was filled with neutral hydrogen gas that is opaque at short wavelengths of light, such as ultraviolet. However, this ultraviolet light was the neutral hydrogen's worst enemy, gradually ionizing the gas across the universe. Once ionized, hydrogen gas cannot absorb ultraviolet light — and so, the cosmos became transparent at those wavelengths.
Because of this, the first billion or so years are called the Epoch of Reionization. It is referred to as "reionization" rather than ionization because, technically, the gas had already been ionized once before during the first 379,000 years after the Big Bang.
While investigating what brought about this epoch, astronomers had identified two chief suspects that could have produced sufficient amounts of ultraviolet light to ionize the neutral hydrogen. One is active supermassive black holes and the other is the first generations of hot, massive stars. The problem is, given that neutral hydrogen is adept at absorbing the ultraviolet light, astronomers have had difficulty tracing that ultraviolet back to its source and identifying which of the two suspects are the main culprit.
In 2023 the James Webb Space Telescope (JWST) made a major breakthrough, finding a galaxy that existed just 900 million years after the Big Bang that was producing enough energy to ionize the neutral gas surrounding it.
Now the Hubble Space Telescope has gone further, detecting ultraviolet light from a galaxy called MXDFz4.4. This ultraviolet light should only be visible if the surrounding gas had already been ionized.
"Observing a galaxy like this was thought to be impossible," said Ilias Goovaerts of the Space Telescope Science Institute (STScI) in Baltimore, who led the discovery, in a statement. "Researchers expected the 'fog' of neutral hydrogen that filled the early universe would be too thick and obscure our view of its ionizing light. Hubble not only spotted that light, but it also helped reveal incredible details about the galaxy's characteristics."

MXDFz4.4 was first identified in the MUSE eXtremely Deep Field (MXDF), with MUSE being the Multi Unit Spectroscopic Explorer on the European Southern Observatory's Very Large Telescope in Chile. The "z4.4" part of its name tells us that the galaxy exists at a redshift of 4.4, meaning that it existed 12.37 billion years ago. As the universe has expanded in the time since then, the ultraviolet light has been redshifted into visible wavelengths that were detected by Hubble.
"Astronomers have found many galaxies that existed at this point in the history of the universe, but we haven't detected ionizing photons from any of them, making MXDFz4.4 one of a kind," said Marc Rafelski, who is the Hubble Deputy Mission Head at STScI.
MXDFz4.4 is 100 times smaller than our Milky Way galaxy but is forming stars ten times faster than our galaxy is. Many of those stars are being born in the tight, luminous cluster producing the ionizing ultraviolet.

The cluster contains "A lot of young, hot, massive stars in a small space [that] do a better job of blasting through opaque gas," said Goovaerts.
Furthermore, by comparing Hubble's observations of MXDFz.4.4 with those of the JWST, which probed for cooler, older stars in the galaxy, Goovaerts and Rafelski's team discovered that the stars in the cluster had formed in bursts, each burst producing fresh quantities of ionizing ultraviolet radiation that helped to clear out more and more of the neutral gas over time. We now see the galaxy about 250 million years after it finished reionizing the surrounding gas. These hot, massive stars in the cluster end their lives after a few million years as supernova explosions, the blast waves and radiation from which can create bubbles in the gas light years across, creating further pathways for ultraviolet light to escape and be detected by Hubble.
The observations seem to nail down the theory that clusters of hot, massive, luminous stars in young galaxies in the early universe played a dominant role in ionizing the universe's neutral gas.
"Hubble's observations of MXDFz4.4 let us test our hypotheses much closer to the Era of Reionization than ever before," said Rafelski. "Finding more galaxies, especially at slightly later cosmic times where larger samples are within reach, would let us refine these measurements and figure out what cleared our view as that era was ending."
The results were published on June 23 in The Astrophysical Journal.
Hubble Glimpses Merging Galaxy Clusters
2 min read
Hubble Glimpses Merging Galaxy Clusters

This NASA Hubble Space Telescope image features a galaxy cluster, called CL0016+1609 or MACS J0018.5+1626, that is very bright at X-ray wavelengths and is one of the most extensively studied clusters at X-ray and radio wavelengths. The X-ray observations of this cluster revealed that it is two clusters merging along our line of sight.
Researchers requested time to observe CL0016+1609 with Hubble’s Advanced Camera for Surveys because that data would help them accurately measure the cluster’s dark-matter distribution, which helps them study the merger and the role of CL0016+1609 in the large-scale structure of the universe. Hubble can’t directly see dark matter, but its infrared and visible light observations can detect dark matter’s gravitational lensing effects on the normal matter Hubble observes.
The data in this image also includes observations with Hubble’s Wide Field Camera 3 taken as part of an observing program that obtained the first Hubble infrared images of 46 massive galaxy clusters and looked for distant galaxies gravitationally lensed by these clusters. Called RELICS (Reionization Lensing Cluster Survey), this survey found some 300 high-redshift candidate galaxies lensed by these clusters.
You can see the faint vertical arc of one of these distant galaxies in the image above. Look for it just to the left of the large elliptical galaxies in the center of the image. Another brighter, though shorter arc is visible just above and to the right of the large elliptical galaxies in the center of the image.
Media Contact:
Claire Andreoli
NASA’s Goddard Space Flight Center, Greenbelt, MD
claire.andreoli@nasa.gov
Discover More Topics From Hubble
Hubble Glimpses Merging Galaxy Clusters
2 min read
Hubble Glimpses Merging Galaxy Clusters

This NASA Hubble Space Telescope image features a galaxy cluster, called CL0016+1609 or MACS J0018.5+1626, that is very bright at X-ray wavelengths and is one of the most extensively studied clusters at X-ray and radio wavelengths. The X-ray observations of this cluster revealed that it is two clusters merging along our line of sight.
Researchers requested time to observe CL0016+1609 with Hubble’s Advanced Camera for Surveys because that data would help them accurately measure the cluster’s dark-matter distribution, which helps them study the merger and the role of CL0016+1609 in the large-scale structure of the universe. Hubble can’t directly see dark matter, but its infrared and visible light observations can detect dark matter’s gravitational lensing effects on the normal matter Hubble observes.
The data in this image also includes observations with Hubble’s Wide Field Camera 3 taken as part of an observing program that obtained the first Hubble infrared images of 46 massive galaxy clusters and looked for distant galaxies gravitationally lensed by these clusters. Called RELICS (Reionization Lensing Cluster Survey), this survey found some 300 high-redshift candidate galaxies lensed by these clusters.
You can see the faint vertical arc of one of these distant galaxies in the image above. Look for it just to the left of the large elliptical galaxies in the center of the image. Another brighter, though shorter arc is visible just above and to the right of the large elliptical galaxies in the center of the image.
Media Contact:
Claire Andreoli
NASA’s Goddard Space Flight Center, Greenbelt, MD
claire.andreoli@nasa.gov
Discover More Topics From Hubble
The post Hubble Glimpses Merging Galaxy Clusters appeared first on NASA Science.
NASA Webb, Hubble Reveal History of Relic of Milky Way’s Formation
NASA Webb, Hubble Reveal History of Relic of Milky Way’s Formation

Image: NASA, ESA, CSA, STScI, Giorgia Zullo (University of Bologna), Francesco Ferraro (University of Bologna); Image Processing: Alyssa Pagan (STScI)
Researchers using two of humanity’s most powerful observatories — NASA’s James Webb and Hubble Space Telescopes — have definitively shown that Terzan 5 is not a globular star cluster as it was once classified, offering new insight into how galaxies like our own form and evolve over time. A globular star cluster typically has only one ancient star population. New data not only confirms the existence of two distinct populations of stars in Terzan 5, but also provides evidence for two more recent rounds of star formation. Although located within the crowded bulge of our Milky Way, our galaxy’s central, spherical region of older stars, Terzan 5 was massive enough to maintain its separate identity while lighter weight systems spread out and mixed to form the bulge billions of years ago. It’s like a lump in an otherwise well-mixed cake batter.
“Webb’s new near-infrared observations, cross-referenced with Hubble’s archival observations, have given us a much clearer picture of the history of Terzan 5,” said Giorgia Zullo, who led the research and is a PhD student at the University of Bologna in Italy.
These results were presented at a press conference Tuesday at the 248th meeting of the American Astronomical Society in Pasadena, and were published in Astronomy & Astrophysics.
Image: Bulge Fossil Fragment Terzan 5 (Webb and Hubble Image)

Four generations of stars
Discovered in 1968 by astronomer Azop Terzan, Terzan 5 resembles a globular cluster in many ways. However, in 2009 this system was discovered to harbor two distinct populations of stars. In 2016 Hubble provided the first estimate of their ages, showing that one formed roughly 12 billion years ago — as the Milky Way itself was assembling — and the other about 5 billion years ago, just before Earth started forming. This pointed to a more complex history than a typical globular cluster.
Studying Terzan 5 is complicated by its location in a region of our galaxy crowded with stars and heavily obscured by dust. This is where Webb stepped in. Its infrared view allowed the research team to peer through the dust and catalog many more stars, and fainter stars, than previous work. By measuring star colors and brightnesses, astronomers can classify them into populations of different ages and chemistries.
Webb was able to measure these key properties for every star within the field of view in the sky — both stars within Terzan 5 and unrelated foreground stars. To isolate the stars of Terzan 5, the team relied on the power and longevity of Hubble. The 12-year separation allowed the team to measure very small movements of individual stars, known as proper motions, to determine which stars belong to Terzan 5 and which are part of the Milky Way bulge.
By combining data from both Webb and Hubble, the researchers found strong evidence for two more stellar populations, one that formed 3.8 billion years ago and another only 2.5 billion years ago. They also were able to determine the ages of the previously known stellar populations with unprecedented precision, finding that they formed 12.5 billion and 4.7 billion years ago.
With the previously known two generations of stars, astronomers could not rule out the possibility that Terzan 5 interacted with another object, like a globular cluster or a giant molecular cloud, becoming enriched with new gas and dust that set off a second round of star formation. With four stellar generations, those explanations are ruled out.
Measurements of the stellar composition of Terzan 5 populations made at the W. M. Keck Observatory and European Southern Observatory’s Very Large Telescope also point toward very distinct populations. “Along with the ages of these populations, the cluster preserves a fossil record of progressive enrichment of heavy elements by supernovae,” said co-author R. Michael Rich, a research astronomer at the University of California, Los Angeles.
Terzan 5 formed multiple generations of stars because it was able to retain the necessary raw materials. There is evidence of powerful supernova explosions in Terzan 5 that forged heavier elements that were swept up by subsequent generations of stars. In lighter weight systems, the force of the explosions themselves could have ejected the resulting elements as well as sweeping out leftover gas and dust. The progenitor of Terzan 5 had enough mass to retain those stars’ ejections, allowing new generations of stars to form over billions of years.
‘Bulge fossil fragment’
The results show that Terzan 5 is most likely the remnant of a much more massive stellar system that initially formed 12.5 billion years ago. Terzan 5 is extraordinary because it survived — and never merged or fully “mixed in” with the Milky Way’s bulge. “For some reason, this peculiar clump of stars formed separately from the bulge and was not destroyed as the bulge itself formed,” said Francesco R. Ferraro, a professor at the University of Bologna and principal investigator of the Webb observations. “Terzan 5 is what we now call a bulge fossil fragment because it resembles the primordial clumps that contributed to the formation of the bulge.”
To date, there’s one other known cosmic object like Terzan 5. Liller 1 was the second to be reclassified from a globular star cluster to a bulge fossil fragment. It also contains multiple generations of stars. There may be more objects like it. Between 40 to 50 additional globular clusters that orbit within the bulge will be examined by Ferraro’s team to determine if their stellar populations are all the same, like globular clusters, or have several generations, like bulge fossil fragments.
Video: Zoom to See Terzan 5 Near Our Milky Way Galaxy’s Bulge
Potential parallels for galaxy formation near, far
Ultimately, this research may improve what we know about how the central bulges of galaxies form over hundreds of millions of years. “Based on observations and in-depth simulations, we think that galaxies in the early universe had huge disks of gas that fragmented into clumps and formed stars. These clumps migrated to the center of the galaxies, and many merged to form their bulges,” said Barbara Lanzoni, a co-author and associate professor at the University of Bologna. For example, Webb has turned up several examples of “clumpy” galaxies that were actively forming when the universe was only a few hundred million years old, like the clumps in the Firefly Sparkle galaxy. “Terzan 5 may provide direct evidence that can help explain how bulges formed in galaxies throughout the universe,” Lanzoni said.
The James Webb Space Telescope is the world’s premier space science observatory. Webb is solving mysteries in our solar system, looking beyond to distant worlds around other stars, and probing the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners, ESA (European Space Agency) and CSA (Canadian Space Agency).
The Hubble Space Telescope has been operating for over 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, based in Denver, 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.
To learn more about Webb, visit:
To learn more about Hubble, visit:
https://science.nasa.gov/hubble
Downloads & Related Information
The following sections contain links to download this article’s images and videos in all available resolutions followed by related information links, media contacts, and if available, research paper and Spanish translation links.
Related Images & Videos

Bulge Fossil Fragment Terzan 5 (Webb and Hubble Image)
New observations from Webb combined with multiple observations from Hubble prove that Terzan 5 is a self-contained, self-enriching stellar system that contains up to four distinct star populations. It orbits within our Milky Way galaxy’s central bulge.

Terzan 5 (Webb and Hubble Compass Image)
This image of bulge fossil fragment Terzan 5 was captured by the James Webb and Hubble space telescopes. Webb’s data are from its NIRCam (Near-Infrared Camera) and Hubble’s from its Advanced Camera for Surveys (ACS). The image shows a scale bar, compass arrows, and co…

Zoom to See Terzan 5 Near Our Milky Way Galaxy’s Bulge
Zoom in to Terzan 5, a star cluster that lies within the crowded central region of our Milky Way galaxy known as the bulge. The scene starts with a ground-based image of our Milky Way bulge and zooms in on and circles Terzan 5, ending with the composite image of the star system f…
Related Links
Read more: Hubble’s star clusters
Explore more: ViewSpace | Forms of light: the Cluster Omega Centauri
Watch: Globular Clusters, Stellar Pockets
Watch: Sorting the Stars in Omega Centauri
Webb: News | Images | Science | Home Page
Hubble: News | Images | Science | Home Page
Details
Laura Betz
NASA’s Goddard Space Flight Center
Greenbelt, Maryland
laura.e.betz@nasa.gov
Christine Pulliam
Space Telescope Science Institute
Baltimore, Maryland
Claire Blome
Space Telescope Science Institute
Baltimore, Maryland
NASA Webb, Hubble Reveal History of Relic of Milky Way’s Formation
NASA Webb, Hubble Reveal History of Relic of Milky Way’s Formation

Researchers using two of humanity’s most powerful observatories — NASA’s James Webb and Hubble Space Telescopes — have definitively shown that Terzan 5 is not a globular star cluster as it was once classified, offering new insight into how galaxies like our own form and evolve over time. A globular star cluster typically has only one ancient star population. New data not only confirms the existence of two distinct populations of stars in Terzan 5, but also provides evidence for two more recent rounds of star formation. Although located within the crowded bulge of our Milky Way, our galaxy’s central, spherical region of older stars, Terzan 5 was massive enough to maintain its separate identity while lighter weight systems spread out and mixed to form the bulge billions of years ago. It’s like a lump in an otherwise well-mixed cake batter.
“Webb’s new near-infrared observations, cross-referenced with Hubble’s archival observations, have given us a much clearer picture of the history of Terzan 5,” said Giorgia Zullo, who led the research and is a PhD student at the University of Bologna in Italy.
These results were presented at a press conference Tuesday at the 248th meeting of the American Astronomical Society in Pasadena, and were published in Astronomy & Astrophysics.
Image: Bulge Fossil Fragment Terzan 5 (Webb and Hubble Image)

Four generations of stars
Discovered in 1968 by astronomer Azop Terzan, Terzan 5 resembles a globular cluster in many ways. However, in 2009 this system was discovered to harbor two distinct populations of stars. In 2016 Hubble provided the first estimate of their ages, showing that one formed roughly 12 billion years ago — as the Milky Way itself was assembling — and the other about 5 billion years ago, just before Earth started forming. This pointed to a more complex history than a typical globular cluster.
Studying Terzan 5 is complicated by its location in a region of our galaxy crowded with stars and heavily obscured by dust. This is where Webb stepped in. Its infrared view allowed the research team to peer through the dust and catalog many more stars, and fainter stars, than previous work. By measuring star colors and brightnesses, astronomers can classify them into populations of different ages and chemistries.
Webb was able to measure these key properties for every star within the field of view in the sky — both stars within Terzan 5 and unrelated foreground stars. To isolate the stars of Terzan 5, the team relied on the power and longevity of Hubble. The 12-year separation allowed the team to measure very small movements of individual stars, known as proper motions, to determine which stars belong to Terzan 5 and which are part of the Milky Way bulge.
By combining data from both Webb and Hubble, the researchers found strong evidence for two more stellar populations, one that formed 3.8 billion years ago and another only 2.5 billion years ago. They also were able to determine the ages of the previously known stellar populations with unprecedented precision, finding that they formed 12.5 billion and 4.7 billion years ago.
With the previously known two generations of stars, astronomers could not rule out the possibility that Terzan 5 interacted with another object, like a globular cluster or a giant molecular cloud, becoming enriched with new gas and dust that set off a second round of star formation. With four stellar generations, those explanations are ruled out.
Measurements of the stellar composition of Terzan 5 populations made at the W. M. Keck Observatory and European Southern Observatory’s Very Large Telescope also point toward very distinct populations. “Along with the ages of these populations, the cluster preserves a fossil record of progressive enrichment of heavy elements by supernovae,” said co-author R. Michael Rich, a research astronomer at the University of California, Los Angeles.
Terzan 5 formed multiple generations of stars because it was able to retain the necessary raw materials. There is evidence of powerful supernova explosions in Terzan 5 that forged heavier elements that were swept up by subsequent generations of stars. In lighter weight systems, the force of the explosions themselves could have ejected the resulting elements as well as sweeping out leftover gas and dust. The progenitor of Terzan 5 had enough mass to retain those stars’ ejections, allowing new generations of stars to form over billions of years.
‘Bulge fossil fragment’
The results show that Terzan 5 is most likely the remnant of a much more massive stellar system that initially formed 12.5 billion years ago. Terzan 5 is extraordinary because it survived — and never merged or fully “mixed in” with the Milky Way’s bulge. “For some reason, this peculiar clump of stars formed separately from the bulge and was not destroyed as the bulge itself formed,” said Francesco R. Ferraro, a professor at the University of Bologna and principal investigator of the Webb observations. “Terzan 5 is what we now call a bulge fossil fragment because it resembles the primordial clumps that contributed to the formation of the bulge.”
To date, there’s one other known cosmic object like Terzan 5. Liller 1 was the second to be reclassified from a globular star cluster to a bulge fossil fragment. It also contains multiple generations of stars. There may be more objects like it. Between 40 to 50 additional globular clusters that orbit within the bulge will be examined by Ferraro’s team to determine if their stellar populations are all the same, like globular clusters, or have several generations, like bulge fossil fragments.
Video: Zoom to See Terzan 5 Near Our Milky Way Galaxy’s Bulge
Potential parallels for galaxy formation near, far
Ultimately, this research may improve what we know about how the central bulges of galaxies form over hundreds of millions of years. “Based on observations and in-depth simulations, we think that galaxies in the early universe had huge disks of gas that fragmented into clumps and formed stars. These clumps migrated to the center of the galaxies, and many merged to form their bulges,” said Barbara Lanzoni, a co-author and associate professor at the University of Bologna. For example, Webb has turned up several examples of “clumpy” galaxies that were actively forming when the universe was only a few hundred million years old, like the clumps in the Firefly Sparkle galaxy. “Terzan 5 may provide direct evidence that can help explain how bulges formed in galaxies throughout the universe,” Lanzoni said.
The James Webb Space Telescope is the world’s premier space science observatory. Webb is solving mysteries in our solar system, looking beyond to distant worlds around other stars, and probing the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners, ESA (European Space Agency) and CSA (Canadian Space Agency).
The Hubble Space Telescope has been operating for over 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, based in Denver, 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.
To learn more about Webb, visit:
To learn more about Hubble, visit:
https://science.nasa.gov/hubble
Downloads & Related Information
The following sections contain links to download this article’s images and videos in all available resolutions followed by related information links, media contacts, and if available, research paper and Spanish translation links.
Related Images & Videos

Bulge Fossil Fragment Terzan 5 (Webb and Hubble Image)
New observations from Webb combined with multiple observations from Hubble prove that Terzan 5 is a self-contained, self-enriching stellar system that contains up to four distinct star populations. It orbits within our Milky Way galaxy’s central bulge.

Terzan 5 (Webb and Hubble Compass Image)
This image of bulge fossil fragment Terzan 5 was captured by the James Webb and Hubble space telescopes. Webb’s data are from its NIRCam (Near-Infrared Camera) and Hubble’s from its Advanced Camera for Surveys (ACS). The image shows a scale bar, compass arrows, and co…

Zoom to See Terzan 5 Near Our Milky Way Galaxy’s Bulge
Zoom in to Terzan 5, a star cluster that lies within the crowded central region of our Milky Way galaxy known as the bulge. The scene starts with a ground-based image of our Milky Way bulge and zooms in on and circles Terzan 5, ending with the composite image of the star system f…
Related Links
Read more: Hubble’s star clusters
Explore more: ViewSpace | Forms of light: the Cluster Omega Centauri
Watch: Globular Clusters, Stellar Pockets
Watch: Sorting the Stars in Omega Centauri
Webb: News | Images | Science | Home Page
Hubble: News | Images | Science | Home Page
Details
Laura Betz
NASA’s Goddard Space Flight Center
Greenbelt, Maryland
laura.e.betz@nasa.gov
Christine Pulliam
Space Telescope Science Institute
Baltimore, Maryland
Claire Blome
Space Telescope Science Institute
Baltimore, Maryland
The post NASA Webb, Hubble Reveal History of Relic of Milky Way’s Formation appeared first on NASA Science.
NASA’s Chandra Finds Unexpected Fireworks in Aftermath of Stellar Explosions
NASA’s Chandra Finds Unexpected Fireworks in Aftermath of Stellar Explosions

The aftermath of a supernova, a stellar explosion, is usually a slowly fading cloud of hot gas. So when astronomers pointed NASA’s Chandra X-ray Observatory at the nearby galaxy Messier 83 (M83), they did not expect to find a population of supernova remnants, or the debris from these explosions, showing dramatic changes in their brightness. The new results were presented at the American Astronomical Society meeting in Pasadena, California, and published in The Astrophysical Journal.
The galaxy M83, located about 15 million light-years from Earth, is forming stars at a high rate. Researchers analyzed 14 years of Chandra data of the galaxy, spanning 2000 to 2014.
Using this extensive set of data, the researchers caught surprising variations in the X-ray brightness of sources previously identified as supernova remnants. The researchers expected supernova remnants older than a century or so to fade gradually in X-rays, but not change dramatically in brightness.
The team found that roughly half of the 22 X-ray sources associated with supernova remnants in their sample showed changes in X-ray brightness over the 14-year span of observations — a result that was completely unexpected.
“We knew that individual X-ray sources could vary dramatically,” said Andrea Prestwich, of the Catholic University of America who led the study. “But finding that so many supernova remnants were behaving this way was a real surprise. Something unusual is going on in these objects. Pinpointing the cause remains a challenge, as M83’s distance limits the detail we can observe.”
One of the 22 variable supernova remnants has a straightforward explanation: SN 1957D, the debris from a supernova first observed nearly 70 years ago, is ramming into material surrounding the explosion site, producing the observed X-ray flares. But this cannot explain the rest of the sample. There is no evidence to suggest that all 22 remnants were formed within the last century. Something else must be driving the variability.
The most likely explanation is that the team has uncovered a population of stellar survivors stars that lived through their partner’s destruction in a supernova explosion. In this scenario, each variable X-ray source began as a pair of massive stars orbiting each other. The more massive star collapsed and exploded as a supernova, leaving behind a black hole or ultra-dense neutron star. Its companion survived.
“It may be that this galaxy contains a collection of supernova remnants where one massive star survives the supernova and becomes locked into an orbit with a black hole or neutron star,” said co-author Michael McCollough of the Center for Astrophysics | Harvard & Smithsonian (CfA). “The neutron star or black hole can then start pulling material from the massive star’s surface.”
That infalling material is superheated by the intense gravitational pull, producing the X-rays Chandra detects. These types of systems, known as high-mass X-ray binaries (HMXBs), are among the most variable X-ray sources in the universe. Researchers say they may be the cause of the variations seen in M83’s supernova remnants.
Astronomers have known about HMXBs for decades, but the difference with this group in M83 is their connection to supernova remnants. Previously, only a handful of supernova remnants associated with HMXBs had been identified across observations of all galaxies. It is unprecedented to find more than 20 strong candidates in just one galaxy.
The authors found that the variable supernova remnants are in regions with higher concentrations of massive stars than in other parts of the galaxy, increasing the chances of a link between the remnants and HMXBs.
There is another possible explanation: Instead of pulling in material from a companion star, the black hole or neutron star may be recapturing some of the material blasted outward by the original explosion.
“This could be an example of cosmic recycling, where debris from the explosion falls back onto the very object the supernova created,” said co-author Roy Kilgard of Wesleyan University. “And it’s quite possible that both explanations are at play — different sources in our sample may have different origins.”
These results are not unique to M83. A follow-up study of the nearby star-forming galaxy M51 by Zoe Hoiland of Vassar College and Kilgard has uncovered a similar population of variable X-ray sources associated with supernova remnants, suggesting that such systems may be a feature of galaxies undergoing vigorous star formation.

The Chandra data for M83 began with single observations in 2000 and 2001, followed by 10 observations from 2010 to 2011 and another observation in 2014.
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.
Visual Description
This release features a composite image of the nearby galaxy Messier 83, and short timelapse videos of two curious supernova remnants hidden inside.
In the composite image, Messier 83, or M83, is shown to have a spiral structure, viewed straight on. At the center is a brilliant white and yellow pool of light. From that light, spiral arms of hot pink cloud corkscrew out in wide, sweeping arches. The galaxy is covered in a faint grey haze, and flecked with red, green, blue, white, and yellow dots.
In an annotated version of the composite image, two tiny dots to our lower right of center are highlighted by white circles. These are two of the supernova remnants being considered by researchers. Each is examined further in a separate timelapse video.
Over a 14-year period from 2000 to 2014, astronomers pointed NASA’s X-ray observatory at the M83 galaxy. They discovered that about half of the X-ray sources believed to be supernova remnants, the aftermath of stellar explosions, were exhibiting dramatic changes in brightness. This result was entirely unexpected.
Those changes in brightness are highlighted in the timelapse videos. In each video, a series of static images flashes by, focused on one of the two X-ray sources once believed to be supernova remnants. In the videos, the X-ray sources appear as bright blue blobs with glowing cores. But in each image, taken months or years apart, the shapes change, as does the intensity of the blue color, and the brightness of the core. By presenting the substantively different images of the same objects one after another in quick succession, short timelapse videos are created.
The most likely explanation for the changes in brightness is that the team has uncovered a population of stellar survivors, stars that lived through an orbiting partner’s destruction in a supernova explosion. Material is being pulled from the surviving star onto the black hole or neutron star that formed in the supernova, a process known to cause rapid changes in X-ray brightness.
Read more from NASA’s Chandra X-ray Observatory
To learn more about NASA’s Chandra mission, visit:
https://science.nasa.gov/chandra
News Media Contact
Megan Watzke
Chandra X-ray Center
Cambridge, Mass.
617-496-7998
mwatzke@cfa.harvard.edu
Joel Wallace
Marshall Space Flight Center, Huntsville, Alabama
256-544-0034
joel.w.wallace@nasa.gov
About the Author
Lee Mohon
Details
Explore More
Discover More Topics From NASA
Chandra X-ray Observatory
The Chandra X-ray Observatory is the world’s most powerful X-ray telescope.

James Webb Space Telescope
Webb is the premier observatory of the next decade, serving thousands of astronomers worldwide. It studies every phase in the…

Hubble Space Telescope
Since its 1990 launch, the Hubble Space Telescope has changed our fundamental understanding of the universe.

Universe

NASA’s Chandra Finds Unexpected Fireworks in Aftermath of Stellar Explosions
NASA’s Chandra Finds Unexpected Fireworks in Aftermath of Stellar Explosions

The aftermath of a supernova, a stellar explosion, is usually a slowly fading cloud of hot gas. So when astronomers pointed NASA’s Chandra X-ray Observatory at the nearby galaxy Messier 83 (M83), they did not expect to find a population of supernova remnants, or the debris from these explosions, showing dramatic changes in their brightness. The new results were presented at the American Astronomical Society meeting in Pasadena, California, and published in The Astrophysical Journal.
The galaxy M83, located about 15 million light-years from Earth, is forming stars at a high rate. Researchers analyzed 14 years of Chandra data of the galaxy, spanning 2000 to 2014.
Using this extensive set of data, the researchers caught surprising variations in the X-ray brightness of sources previously identified as supernova remnants. The researchers expected supernova remnants older than a century or so to fade gradually in X-rays, but not change dramatically in brightness.
The team found that roughly half of the 22 X-ray sources associated with supernova remnants in their sample showed changes in X-ray brightness over the 14-year span of observations — a result that was completely unexpected.
“We knew that individual X-ray sources could vary dramatically,” said Andrea Prestwich, of the Catholic University of America who led the study. “But finding that so many supernova remnants were behaving this way was a real surprise. Something unusual is going on in these objects. Pinpointing the cause remains a challenge, as M83’s distance limits the detail we can observe.”
One of the 22 variable supernova remnants has a straightforward explanation: SN 1957D, the debris from a supernova first observed nearly 70 years ago, is ramming into material surrounding the explosion site, producing the observed X-ray flares. But this cannot explain the rest of the sample. There is no evidence to suggest that all 22 remnants were formed within the last century. Something else must be driving the variability.
The most likely explanation is that the team has uncovered a population of stellar survivors stars that lived through their partner’s destruction in a supernova explosion. In this scenario, each variable X-ray source began as a pair of massive stars orbiting each other. The more massive star collapsed and exploded as a supernova, leaving behind a black hole or ultra-dense neutron star. Its companion survived.
“It may be that this galaxy contains a collection of supernova remnants where one massive star survives the supernova and becomes locked into an orbit with a black hole or neutron star,” said co-author Michael McCollough of the Center for Astrophysics | Harvard & Smithsonian (CfA). “The neutron star or black hole can then start pulling material from the massive star’s surface.”
That infalling material is superheated by the intense gravitational pull, producing the X-rays Chandra detects. These types of systems, known as high-mass X-ray binaries (HMXBs), are among the most variable X-ray sources in the universe. Researchers say they may be the cause of the variations seen in M83’s supernova remnants.
Astronomers have known about HMXBs for decades, but the difference with this group in M83 is their connection to supernova remnants. Previously, only a handful of supernova remnants associated with HMXBs had been identified across observations of all galaxies. It is unprecedented to find more than 20 strong candidates in just one galaxy.
The authors found that the variable supernova remnants are in regions with higher concentrations of massive stars than in other parts of the galaxy, increasing the chances of a link between the remnants and HMXBs.
There is another possible explanation: Instead of pulling in material from a companion star, the black hole or neutron star may be recapturing some of the material blasted outward by the original explosion.
“This could be an example of cosmic recycling, where debris from the explosion falls back onto the very object the supernova created,” said co-author Roy Kilgard of Wesleyan University. “And it’s quite possible that both explanations are at play — different sources in our sample may have different origins.”
These results are not unique to M83. A follow-up study of the nearby star-forming galaxy M51 by Zoe Hoiland of Vassar College and Kilgard has uncovered a similar population of variable X-ray sources associated with supernova remnants, suggesting that such systems may be a feature of galaxies undergoing vigorous star formation.

The Chandra data for M83 began with single observations in 2000 and 2001, followed by 10 observations from 2010 to 2011 and another observation in 2014.
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.
Visual Description
This release features a composite image of the nearby galaxy Messier 83, and short timelapse videos of two curious supernova remnants hidden inside.
In the composite image, Messier 83, or M83, is shown to have a spiral structure, viewed straight on. At the center is a brilliant white and yellow pool of light. From that light, spiral arms of hot pink cloud corkscrew out in wide, sweeping arches. The galaxy is covered in a faint grey haze, and flecked with red, green, blue, white, and yellow dots.
In an annotated version of the composite image, two tiny dots to our lower right of center are highlighted by white circles. These are two of the supernova remnants being considered by researchers. Each is examined further in a separate timelapse video.
Over a 14-year period from 2000 to 2014, astronomers pointed NASA’s X-ray observatory at the M83 galaxy. They discovered that about half of the X-ray sources believed to be supernova remnants, the aftermath of stellar explosions, were exhibiting dramatic changes in brightness. This result was entirely unexpected.
Those changes in brightness are highlighted in the timelapse videos. In each video, a series of static images flashes by, focused on one of the two X-ray sources once believed to be supernova remnants. In the videos, the X-ray sources appear as bright blue blobs with glowing cores. But in each image, taken months or years apart, the shapes change, as does the intensity of the blue color, and the brightness of the core. By presenting the substantively different images of the same objects one after another in quick succession, short timelapse videos are created.
The most likely explanation for the changes in brightness is that the team has uncovered a population of stellar survivors, stars that lived through an orbiting partner’s destruction in a supernova explosion. Material is being pulled from the surviving star onto the black hole or neutron star that formed in the supernova, a process known to cause rapid changes in X-ray brightness.
Read more from NASA’s Chandra X-ray Observatory
To learn more about NASA’s Chandra mission, visit:
https://science.nasa.gov/chandra
News Media Contact
Megan Watzke
Chandra X-ray Center
Cambridge, Mass.
617-496-7998
mwatzke@cfa.harvard.edu
Joel Wallace
Marshall Space Flight Center, Huntsville, Alabama
256-544-0034
joel.w.wallace@nasa.gov
About the Author
Lee Mohon
Details
Explore More
Discover More Topics From NASA
Chandra X-ray Observatory
The Chandra X-ray Observatory is the world's most powerful X-ray telescope.

James Webb Space Telescope
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- Hubble spies a swarm of stars in a strange, irregular galaxy | Space photo of the day for June 15, 2026
Hubble spies a swarm of stars in a strange, irregular galaxy | Space photo of the day for June 15, 2026
Black Eye Galaxy

This March 20, 2026, image of Messier 64, or the Black Eye Galaxy, is a composite view from NASA’s Hubble Space Telescope and James Webb Space Telescope. It shows Messier 64 captured at near- and mid-infrared wavelengths by Webb, while Hubble’s image shows the galaxy in ultraviolet, visible, and near-infrared light.
Messier 64 is characterized by its bizarre internal motion. The gas in the outer regions of this spiral galaxy is rotating in the opposite direction from the gas and stars in its inner regions. This strange behavior may be the result of a merger between M64 and a satellite galaxy over a billion years ago.
Image credit: NASA, CSA, ESA, F. Belfiore (European Southern Observatory – Germany), J. Lee (Space Telescope Science Institute), A. Leroy (The Ohio State University), and D. Thilker (The Johns Hopkins University); Processing: Gladys Kober (NASA/Catholic University of America)
The post Black Eye Galaxy appeared first on NASA Science.
Black Eye Galaxy

This March 20, 2026, image of Messier 64, or the Black Eye Galaxy, is a composite view from NASA’s Hubble Space Telescope and James Webb Space Telescope. It shows Messier 64 captured at near- and mid-infrared wavelengths by Webb, while Hubble’s image shows the galaxy in ultraviolet, visible, and near-infrared light.
Messier 64 is characterized by its bizarre internal motion. The gas in the outer regions of this spiral galaxy is rotating in the opposite direction from the gas and stars in its inner regions. This strange behavior may be the result of a merger between M64 and a satellite galaxy over a billion years ago.
Image credit: NASA, CSA, ESA, F. Belfiore (European Southern Observatory – Germany), J. Lee (Space Telescope Science Institute), A. Leroy (The Ohio State University), and D. Thilker (The Johns Hopkins University); Processing: Gladys Kober (NASA/Catholic University of America)
Hubble Sees Swarm of Galaxies
2 min read
Hubble Sees Swarm of Galaxies

Looking somewhat like a swarm of bees returning to their hive, this NASA Hubble Space Telescope image features the galaxy cluster MACS0329-0211. Galaxy clusters like MACS0329-0211 are important signposts in the story of how the structure of the universe evolved, and are the ultimate telescopic lenses, placing gravitationally lensed galaxies from the earliest stages of the universe into our view.
Zoom into this galaxy swarm and you will find large, oval-shaped elliptical galaxies, and thin spiral and lenticular galaxies viewed from the edge. We can also see the full, face-on view of spiral galaxies and their curving spiral arms. The image’s upper-right quadrant holds faint arcs of distant galaxies gravitationally lensed by the cluster’s massive gravity. The largest of these arcs appears above the bright oval shape of a giant elliptical galaxy. Closer inspection of the image’s center reveals several bright-white intersecting curves that appear as a distorted figure eight. This may be another distant galaxy whose light was magnified and distorted by this massive cluster’s gravity.
Hubble looked at MACS0329-0211 as part of an observing program of X-ray bright galaxy clusters. Researchers used Hubble’s two main cameras, the Advanced Camera for Surveys and its Wide Field Camera 3, to gather data visible and infrared light from the cluster. Hubble’s ability to see such a broad spectrum of light makes it a valuable tool in understanding the very nature of these galaxy clusters.
Media Contact:
Claire Andreoli
NASA’s Goddard Space Flight Center, Greenbelt, MD
claire.andreoli@nasa.gov