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Hubble Details Early Galaxy Transforming Neighborhood

NASA News - Tue, 06/23/2026 - 10:00am

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5 Min Read Hubble Details Early Galaxy Transforming Neighborhood

Detailed visible-light images from Hubble reveal that several bursts of younger stars cleared the space in and around galaxy MXDFz4.4. Astronomers have long sought evidence to explain this transition — and Hubble has provided the first example in this time period.

Credits:
Image: NASA, ESA, CSA, STScI, Ilias Goovaerts (STScI), Marc Rafelski (STScI, JHU), Anton Koekemoer (STScI); Image Processing: Alyssa Pagan (STScI)

Astronomers using NASA’s Hubble Space Telescope have found something they never expected — ultraviolet light from a galaxy that existed just 1.4 billion years after the big bang. That galaxy contains tightly clustered young stars that produce ionizing light capable of transforming the opaque, neutral gas within and immediately around the galaxy, clearing our view. This suggests that similar galaxies in the early universe were responsible for clearing the neutral fog of hydrogen gas that once filled the cosmos.

A paper describing this discovery was published June 23 in the Astrophysical Journal.

The galaxy, cataloged MXDFz4.4, existed at the end of the Era of Reionization, a transformative period in our universe. During roughly the first billion years of the cosmos, the gas between stars and galaxies was opaque to energetic ultraviolet light. As time wore on, gas everywhere became transparent or ionized. The changeover was not like an on/off switch, but likely took hundreds of millions of years. Researchers are still collecting evidence to fully understand how this happened, which is why MXDFz4.4 sets a critical precedent.

“Observing a galaxy like this was thought to be impossible,” said lead author Ilias Goovaerts, a postdoctoral fellow at the Space Telescope Science Institute (STScI) in Baltimore. “Researchers expected the ‘fog’ or 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.”

Detailed visible-light images from Hubble reveal that several bursts of younger stars cleared the space in and around galaxy MXDFz4.4. Astronomers have long sought evidence to explain this transition — and Hubble has provided the first example in this time period. Image: NASA, ESA, CSA, STScI, Ilias Goovaerts (STScI), Marc Rafelski (STScI, JHU), Anton Koekemoer (STScI); Image Processing: Alyssa Pagan (STScI) Great light ‘escape’

Young, massive stars emit ultraviolet light capable of ionizing hydrogen atoms. As this light traveled for over 12 billion years to reach Hubble, space expanded, and the light stretched or redshifted into visible light. Hubble’s wavelength coverage, combined with the sensitivity and resolution of its space-based vantage point, makes it the only telescope capable of capturing this ultraviolet light from the early universe.

“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, a co-author and Hubble deputy mission head at STScI.

Hubble’s long exposures, pulled from several existing surveys, revealed that the galaxy’s young, massive stars are the source of the ultraviolet light, which cleared the surrounding space. These stars formed in bursts within the last few million years of MXDFz4.4’s existence and are crammed together.

Amplifying this crowding effect, MXDFz4.4 is about 100 times smaller by area than our Milky Way galaxy, but is forming stars 10 times faster.

“A lot of young, hot, massive stars in a small space do a better job of blasting through opaque gas,” Goovaerts said. The researchers estimate that 50 to 100% of the young stars’ energetic ionizing light is escaping the surrounding gas.

Massive stars’ lifetimes also play a role, since they live for only a few million years. Many explode as supernovae, releasing gigantic amounts of energy and blowing colossal holes that allow even more light to escape.

This illustration portrays galaxy MXDFz4.4 when it existed 1.4 billion years after the big bang. At this time, the universe was still a mix of opaque and transparent gas as the Era of Reionization was gradually ending. Illustration: NASA, ESA, Leah Hustak (STScI) Partnering with other observatories

Hubble could not do this alone. These conclusions are supported by survey data taken by NASA’s James Webb Space Telescope in near-infrared light and the MUSE eXtremely Deep Field or MXDF, the galaxy’s namesake, captured by the European Southern Observatory’s Very Large Telescope (VLT) in visible light.

The team used Webb’s data to determine the galaxy’s mass, analyze its older stars, and measure the galaxy’s star formation history. The galaxy’s older stars are less massive and cooler, and therefore not responsible for changing the gas around them.

Comparing Hubble and Webb data also showed that recent star formation happened in bursts. “Without Webb to clarify what we saw in Hubble’s images, we couldn’t make these conclusions,” Rafelski said.

Data from the VLT pinpointed when MXDFz4.4 existed: 1.4 billion years after the big bang. Before this discovery, researchers had only identified a galaxy emitting ionized light from a time when the universe was 1.6 billion years old. Only a few additional examples have been identified, and those existed when the universe was about 2 billion years old. MXDFz4.4 brings researchers closer to drawing firm conclusions about how the Era of Reionization unfolded.

Credit: NASA’s Goddard Space Flight Center; Lead Producer: Paul Morris Expanding what we know

Studying the Era of Reionization is a decades-old endeavor. Researchers use statistics about star populations in nearby galaxies, which we can observe in great detail, to make well-informed assumptions about what might be happening in galaxies in the early universe, in part because their star populations are too distant to resolve in any detail.

In 2023, researchers using Webb showed that galaxies’ stars emitted enough light to heat and ionize the gas around them 900 million years after the big bang. This was a breakthrough, but astronomers need galaxies like MXDFz4.4 to fully explain how the process happened, since it shows how the high-energy light from young stars managed to escape the gas and dust within the galaxy itself.

It’s possible other galaxies like MXDFz4.4 are waiting to be discovered.

“Hubble’s observations of MXDFz4.4 let us test our hypotheses much closer to the Era of Reionization than ever before,” Rafelski said. “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 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.

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Related Images & Videos

Galaxy MXDFz4.4 (Hubble and Webb Image)

Detailed visible-light images from Hubble reveal that several bursts of younger stars cleared the space in and around galaxy MXDFz4.4. Astronomers have long sought evidence to explain this transition — and Hubble has provided the first example in this time period.

Galaxy MXDFz4.4 (Artist’s Concept)

This illustration portrays galaxy MXDFz4.4 when it existed 1.4 billion years after the big bang. At this time, the universe was still a mix of opaque and transparent gas as the Era of Reionization was gradually ending.

Galaxy MXDFz4.4 (Hubble and Webb Compass Image)

This shows the galaxy MXDFz4.4, enlarged at right, in the Hubble Ultra Deep Field (HUDF), captured by both the Hubble Space Telescope’s Advanced Camera for Surveys (ACS) and the James Webb Space Telescope’s NIRCam (Near-Infrared Camera).

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Last Updated

Jun 23, 2026

Editor Andrea Gianopoulos Location NASA Goddard Space Flight Center Contact

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

Claire Blome, Christine Pulliam
Space Telescope Science Institute
Baltimore, Maryland

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NASA’s Webb Pinpoints Millions of Stars Within Cigar Galaxy

NASA - Breaking News - Tue, 06/23/2026 - 10:00am

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6 Min Read NASA’s Webb Pinpoints Millions of Stars Within Cigar Galaxy

Scientists used NASA’s James Webb Space Telescope to image edge-on starburst galaxy Messier 82 and trace its evolutionary history. This Webb and Hubble composite image includes 16.5 million stars (blue-white), dust grains (red-orange), and ionized hydrogen gas (yellow).

Credits:
Image: NASA, ESA, CSA, Adam Smercina (STScI, Tufts), Thomas Williams (University of Manchester); Image Processing: Alyssa Pagan (STScI)

Located 12 million light-years away and undergoing rapid star formation, edge-on spiral galaxy Messier 82 (M82) is a scientifically unique sight to behold, and now NASA’s James Webb Space Telescope has revealed previously unseen details.

M82’s intense star formation, thought to be the result of a galaxy merger, will be a short-lived event in astronomical terms, estimated to last a few hundred million years in its entirety. This temporary phase of extreme star formation relative to the galaxy’s mass, as well as its location in the local universe, are among the factors that make M82, also known as the Cigar galaxy, a one-of-a-kind environment to study.

Image: M82 Cigar Galaxy (Webb + Hubble) Scientists used NASA’s James Webb Space Telescope to image edge-on starburst galaxy Messier 82 and trace its evolutionary history. This Webb and Hubble composite image includes 16.5 million stars (blue-white), dust grains (red-orange), and ionized hydrogen gas (yellow). Image: NASA, ESA, CSA, Adam Smercina (STScI, Tufts), Thomas Williams (University of Manchester); Image Processing: Alyssa Pagan (STScI)

A team of astronomers recently completed an imaging survey with the Webb telescope. This program entailed a total of 65 hours of observation time with Webb’s NIRCam (Near-Infrared Camera) instrument and revealed never-seen-before details of the starburst galaxy, including its distended disk structure and millions of individual stars. Webb’s high-resolution imaging, specifically of the main plane of the galactic disk, has unlocked vital information for astronomers as they seek to uncover M82’s formation history. Additionally, the Webb data will help scientists understand the current processes occurring within the starburst galaxy.

“M82 is a mess, but it’s a beautiful mess. We don’t fully understand what’s going on, especially concerning its evolutionary history. What could have triggered such an elevated rate of star formation? How long has this galaxy been driving plumes of material away from its center?” said principal investigator Adam Smercina, a NASA Hubble Fellow at the Space Telescope Science Institute in Baltimore, and incoming Assistant Professor at Tufts University in Massachusetts. “M82 is an ideal galaxy evolution laboratory because it has properties that allow us to probe important physical processes, such as how stars form in such environments and how that activity drives outflows. M82 provides a simultaneous window onto many astrophysical questions, in a way that no other galaxy in the local universe can.”

Image: M82 Cigar Galaxy (NIRCam Image) NASA’s James Webb Space Telescope observed edge-on starburst galaxy Messier 82, peering through dust to reveal 16.5 million stars and the galaxy’s distended disk structure. Scientists seek to learn the galaxy’s evolutionary history with the Webb data. Image: NASA, ESA, CSA, Adam Smercina (STScI, Tufts), Thomas Williams (University of Manchester); Image Processing: Alyssa Pagan (STScI)

Prior to Webb, many observatories looked at the starburst galaxy, including NASA’s Hubble and retired Spitzer space telescopes. However, the sheer volume of dust within that galaxy limited the amount of information astronomers could acquire on M82 at high resolution. While Webb has previously looked at this galaxy, the duration of the new imaging survey, combined with the telescope’s infrared sensitivity, enabled it to pierce through the thick dust.

Image: M82 Cigar Galaxy (Hubble/Webb Side-by-Side) Side-by-side comparison of a portion of starburst galaxy Messier 82 (M82) as seen by NASA’s Hubble (left) and James Webb (right) space telescopes. Hubble detailed M82’s gas and dust structure, while Webb pierced through the dust and resolved millions of stars in infrared light. Image: NASA, ESA, CSA, Adam Smercina (STScI, Tufts), Thomas Williams (University of Manchester); Image Processing: Alyssa Pagan (STScI)

The telescope’s near-infrared-light view is a snapshot of a scene that has been evolving over a couple hundred million years. Webb’s image contains approximately 16.5 million individual stars dispersed throughout the galaxy. The light from these stellar sources is depicted as luminous blue granules. This is only a small portion of the total amount of stars astronomers think reside in a galaxy like M82, with the majority too faint to be seen.

“The sheer number of stars that we were able to resolve with Webb is incredible,” said team member Benjamin Williams of the University of Washington. “It’s a whole different world from what we’ve been able to see with other telescopes. All of these stars collectively provide a detailed fossil record of the formation and evolution of M82.”

Moving inward, the increase in brightness and the asymmetrical shape of the galactic disk hints at the spiral galaxy’s unique underlying structure. The differing radii between the two sides suggests that M82 has a distorted shape, which can happen during intense galaxy mergers.

“At first glance, the disk of the galaxy may seem less spectacular because Webb sees through the dust,” said team member Eric Bell of the University of Michigan. “But M82 is a delightfully complex system. Webb’s observations will help us address some ongoing mysteries, such as how star formation has moved within M82 over the last few billion years.”

Video: M82 Cigar Galaxy (Webb + Hubble Fade)

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NASA’s James Webb Space Telescope’s near-infrared observation of M82 is the most recent addition to overall data on this starburst galaxy. The Hubble Space Telescope is one observatory that has previously looked at M82, detailing the gas and dust structure seen in visible light. Video: NASA, ESA, CSA, STScI, Alyssa Pagan (STScI)

Because of the extreme star formation within the galaxy, which is 10 times faster than the Milky Way galaxy’s star formation rate, stellar birth will eventually be disrupted. M82’s stellar frenzy is causing bipolar plumes of material to be ejected above and below the disk. Though it looks like a tumultuous region, the hourglass-shaped outflows appear to have a layered structure. The yellow tendrils of material closest to the galaxy’s disk represent ionized gas, whereas the orange material farther away depicts small dust grains. These grains are called polycyclic aromatic hydrocarbons and are helpful in tracing material in the space between the galaxy’s stars, also known as the interstellar medium.

The information collected as part of this Webb study is just one dataset scientists will analyze as they seek to piece together this starburst galaxy’s formation history.

“Galaxies are such intricate ecosystems that if you truly want to understand them, you have to pull datasets from different missions together,” said team member Kristen McQuinn of the Space Telescope Science Institute. “One mission cannot fully answer all of the questions we have about M82. Combining the data collected by different telescopes, like Webb and Hubble, is powerful. When you marry the datasets, you expand what you can probe, and the questions that you can pose are even more complex.”

The James Webb Space Telescope is the world’s premier space science observatory. Webb is solving mysteries in our solar system, looking beyond to distant worlds around other stars, and probing the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners, ESA (European Space Agency) and CSA (Canadian Space Agency).

To learn more about Webb, visit:

https://science.nasa.gov/webb

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Related Images & Videos

M82 Cigar Galaxy (Webb + Hubble)

Scientists used NASA’s James Webb Space Telescope to image edge-on starburst galaxy Messier 82 and trace its evolutionary history. This Webb and Hubble composite image includes 16.5 million stars (blue-white), dust grains (red-orange), and ionized hydrogen gas (yellow).

M82 Cigar Galaxy (NIRCam Image)

NASA’s James Webb Space Telescope observed edge-on starburst galaxy Messier 82, peering through dust to reveal 16.5 million stars and the galaxy’s distended disk structure. Scientists seek to learn the galaxy’s evolutionary history with the Webb data.

M82 Cigar Galaxy (Hubble/Webb Side-by-Side)

Side-by-side comparison of a portion of starburst galaxy Messier 82 (M82) as seen by NASA’s Hubble (left) and James Webb (right) space telescopes. Hubble detailed M82’s gas and dust structure, while Webb pierced through the dust and resolved millions of stars in infrared light.

M82 Cigar Galaxy (Compass Image)

Annotated image of the starburst galaxy Messier 82 captured by Webb’s NIRCam (Near-Infrared Camera) instrument, with compass arrows, a scale bar, and color key for reference.

M82 Cigar Galaxy (Webb + Hubble Fade)

NASA’s James Webb Space Telescope’s near-infrared observation of M82 is the most recent addition to overall data on this starburst galaxy. The Hubble Space Telescope is one observatory that has previously looked at M82, detailing the gas and dust structure seen in visible light.

NASA’s Webb Pinpoints Millions of Stars Within Cigar Galaxy

NASA News - Tue, 06/23/2026 - 10:00am

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