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Explore Hubble Hubble Home Overview About Hubble The History of Hubble Hubble Timeline Why Have a Telescope in Space? Hubble by the Numbers At the Museum FAQs Impact & Benefits Hubble’s Impact & Benefits Science Impacts Cultural Impact Technology Benefits Impact on Human Spaceflight Astro Community Impacts Science Hubble Science Science Themes Science Highlights Science Behind Discoveries Hubble’s Partners in Science Universe Uncovered Explore the Night Sky Observatory Hubble Observatory Hubble Design Mission Operations Missions to Hubble Hubble vs Webb Team Hubble Team Career Aspirations Hubble Astronauts Multimedia Images Videos Sonifications Podcasts e-Books Online Activities 3D Hubble Models Lithographs Fact Sheets Posters Hubble on the NASA App Glossary News Hubble News Social Media Media Resources More 35th Anniversary Online Activities 2 min read
Hubble Studies Small but Mighty Galaxy
This NASA/ESA Hubble Space Telescope features the nearby galaxy NGC 4449. ESA/Hubble & NASA, E. Sabbi, D. Calzetti, A. Aloisi This portrait from the NASA/ESA Hubble Space Telescope puts the nearby galaxy NGC 4449 in the spotlight. The galaxy is situated just 12.5 million light-years away in the constellation Canes Venatici (the Hunting Dogs). It is a member of the M94 galaxy group, which is near the Local Group of galaxies that the Milky Way is part of.
NGC 4449 is a dwarf galaxy, which means that it is far smaller and contains fewer stars than the Milky Way. But don’t let its small size fool you — NGC 4449 packs a punch when it comes to making stars! This galaxy is currently forming new stars at a much faster rate than expected for its size, which makes it a starburst galaxy. Most starburst galaxies churn out stars mainly in their centers, but NGC 4449 is alight with brilliant young stars throughout. Researchers believe that this global burst of star formation came about because of NGC 4449’s interactions with its galactic neighbors. Because NGC 4449 is so close, it provides an excellent opportunity for Hubble to study how interactions between galaxies can influence the formation of new stars.
Hubble released an image of NGC 4449 in 2007. This new version incorporates several additional wavelengths of light that Hubble collected for multiple observing programs. These programs encompass an incredible range of science, from a deep dive into NGC 4449’s star-formation history to the mapping of the brightest, hottest, and most massive stars in more than two dozen nearby galaxies.
The NASA/ESA/CSA James Webb Space Telescope has also observed NGC 4449, revealing in intricate detail the galaxy’s tendrils of dusty gas, glowing from the intense starlight radiated by the flourishing young stars.
Text Credit: ESA/Hubble
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Last Updated Jun 20, 2025 Editor Andrea Gianopoulos Location NASA Goddard Space Flight Center Related Terms
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Explore Webb Webb News Latest News Latest Images Webb’s Blog Awards X (offsite – login reqd) Instagram (offsite – login reqd) Facebook (offsite- login reqd) Youtube (offsite) Overview About Who is James Webb? Fact Sheet Impacts+Benefits FAQ Science Overview and Goals Early Universe Galaxies Over Time Star Lifecycle Other Worlds Observatory Overview Launch Deployment Orbit Mirrors Sunshield Instrument: NIRCam Instrument: MIRI Instrument: NIRSpec Instrument: FGS/NIRISS Optical Telescope Element Backplane Spacecraft Bus Instrument Module Multimedia About Webb Images Images Videos What is Webb Observing? 3d Webb in 3d Solar System Podcasts Webb Image Sonifications Webb’s First Images Team International Team People Of Webb More For the Media For Scientists For Educators For Fun/Learning 5 Min Read NASA’s Webb ‘UNCOVERs’ Galaxy Population Driving Cosmic Renovation
White diamonds show the locations of 20 of the 83 young, low-mass, starburst galaxies found in infrared images of the giant galaxy cluster Abell 2744. Full image and description shown below. Credits:
NASA/ESA/CSA/Bezanson et al. 2024 and Wold et al. 2025 Astronomers using data from NASA’s James Webb Space Telescope have identified dozens of small galaxies that played a starring role in a cosmic makeover that transformed the early universe into the one we know today.
“When it comes to producing ultraviolet light, these small galaxies punch well above their weight,” said Isak Wold, an assistant research scientist at Catholic University of America in Washington and NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “Our analysis of these tiny but mighty galaxies is 10 times more sensitive than previous studies, and shows they existed in sufficient numbers and packed enough ultraviolet power to drive this cosmic renovation.”
Wold discussed his findings Wednesday at the 246th meeting of the American Astronomical Society in Anchorage, Alaska. The study took advantage of existing imaging collected by Webb’s NIRCam (Near-Infrared Camera) instrument, as well as new observations made with its NIRSpec (Near-Infrared Spectrograph) instrument.
Image A: Webb search finds dozens of tiny, young star-forming galaxies
Symbols mark the locations of young, low-mass galaxies bursting with new stars when the universe was about 800 million years old. Using a filter sensitive to such galaxies, NASA’s James Webb Space Telescope imaged them with the help of a natural gravitational lens created by the massive galaxy cluster Abell 2744. In all, 83 young galaxies were found, but only the 20 shown here (white diamonds) were selected for deeper study. The inset zooms into one of the galaxies.
Download high-resolution images from NASA’s Scientific Visualization Studio NASA/ESA/CSA/Bezanson et al. 2024 and Wold et al. 2025 The tiny galaxies were discovered by Wold and his Goddard colleagues, Sangeeta Malhotra and James Rhoads, by sifting through Webb images captured as part of the UNCOVER (Ultradeep NIRSpec and NIRCam ObserVations before the Epoch of Reionization) observing program, led by Rachel Bezanson at the University of Pittsburgh in Pennsylvania.
The project mapped a giant galaxy cluster known as Abell 2744, nicknamed Pandora’s cluster, located about 4 billion light-years away in the southern constellation Sculptor. The cluster’s mass forms a gravitational lens that magnifies distant sources, adding to Webb’s already considerable reach.
Image B: Galaxy cluster helps reveal young, low-mass galaxies bursting with stars
White diamonds show the locations of 20 of the 83 young, low-mass, starburst galaxies found in infrared images of the giant galaxy cluster Abell 2744. This composite incorporates images taken through three NIRCam filters (F200W as blue, F410M as green, and F444W as red). The F410M filter is highly sensitive to light emitted by doubly ionized oxygen — oxygen atoms that have been stripped of two electrons — at a time when reionization was well underway. Emitted as green light, the glow was stretched into the infrared as it traversed the expanding universe over billions of years. The cluster’s mass acts as a natural magnifying glass, allowing astronomers to see these tiny galaxies as they were when the universe was about 800 million years old. NASA/ESA/CSA/Bezanson et al. 2024 and Wold et al. 2025 For much of its first billion years, the universe was immersed in a fog of neutral hydrogen gas. Today, this gas is ionized — stripped of its electrons. Astronomers, who refer to this transformation as reionization, have long wondered which types of objects were most responsible: big galaxies, small galaxies, or supermassive black holes in active galaxies. As one of its main goals, NASA’s Webb was specifically designed to address key questions about this major transition in the history of the universe.
Recent studies have shown that small galaxies undergoing vigorous star formation could have played an outsized role. Such galaxies are rare today, making up only about 1% of those around us. But they were abundant when the universe was about 800 million years old, an epoch astronomers refer to as redshift 7, when reionization was well underway.
The team searched for small galaxies of the right cosmic age that showed signs of extreme star formation, called starbursts, in NIRCam images of the cluster.
“Low-mass galaxies gather less neutral hydrogen gas around them, which makes it easier for ionizing ultraviolet light to escape,” Rhoads said. “Likewise, starburst episodes not only produce plentiful ultraviolet light — they also carve channels into a galaxy’s interstellar matter that helps this light break out.”
Image C: A deeper look into small, young, star-forming galaxies during reionization
At left is an enlarged infrared view of galaxy cluster Abell 2744 with three young, star-forming galaxies highlighted by green diamonds. The center column shows close-ups of each galaxy, along with their designations, the amount of magnification provided by the cluster’s gravitational lens, their redshifts (shown as z — all correspond to a cosmic age of about 790 million years), and their estimated mass of stars. At right, measurements from NASA’s James Webb Space Telescope’s NIRSpec instrument confirm that the galaxies produce strong emission in the light of doubly ionized oxygen (green bars), indicating vigorous star formation is taking place. NASA/ESA/CSA/Bezanson et al. 2024 and Wold et al. 2025 The astronomers looked for strong sources of a specific wavelength of light that signifies the presence of high-energy processes: a green line emitted by oxygen atoms that have lost two electrons. Originally emitted as visible light in the early cosmos, the green glow from doubly ionized oxygen was stretched into the infrared as it traversed the expanding universe and eventually reached Webb’s instruments.
This technique revealed 83 small starburst galaxies as they appear when the universe was 800 million years old, or about 6% of its current age of 13.8 billion years. The team selected 20 of these for deeper inspection using NIRSpec.
“These galaxies are so small that, to build the equivalent stellar mass of our own Milky Way galaxy, you’d need from 2,000 to 200,000 of them,” Malhotra said. “But we are able to detect them because of our novel sample selection technique combined with gravitational lensing.”
Image D: Tiny but mighty galaxy helped clear cosmic fog
One of the most interesting galaxies of the study, dubbed 41028 (the green oval at center), has an estimated stellar mass of just 2 million Suns — comparable to the masses of the largest star clusters in our own Milky Way galaxy. NASA/ESA/CSA/Bezanson et al. 2024 and Wold et al. 2025 Similar types of galaxies in the present-day universe, such as green peas, release about 25% of their ionizing ultraviolet light into surrounding space. If the low-mass starburst galaxies explored by Wold and his team release a similar amount, they can account for all of the ultraviolet light needed to convert the universe’s neutral hydrogen to its ionized form.
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:
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NASA’s Goddard Space Flight Center, Greenbelt, Md.
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James Webb Space Telescope (JWST) Astrophysics Galaxies Goddard Space Flight Center Science & Research The Universe View the full article
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By NASA
A black hole has blasted out a surprisingly powerful jet in the distant universe, according to a study from NASA’s Chandra X-ray Observatory.X-ray: NASA/CXC/CfA/J. Maithil et al.; Illustration: NASA/CXC/SAO/M. Weiss; Image Processing: NASA/CXC/SAO/N. Wolk A black hole has blasted out a surprisingly powerful jet in the distant universe, according to a new study from NASA’s Chandra X-ray Observatory and discussed in our latest press release. This jet exists early enough in the cosmos that it is being illuminated by the leftover glow from the big bang itself.
Astronomers used Chandra and the Karl G. Jansky Very Large Array (VLA) to study this black hole and its jet at a period they call “cosmic noon,” which occurred about three billion years after the universe began. During this time most galaxies and supermassive black holes were growing faster than at any other time during the history of the universe.
The main graphic is an artist’s illustration showing material in a disk that is falling towards a supermassive black hole. A jet is blasting away from the black hole towards the upper right, as Chandra detected in the new study. The black hole is located 11.6 billion light-years from Earth when the cosmic microwave background (CMB), the leftover glow from the big bang, was much denser than it is now. As the electrons in the jets fly away from the black hole, they move through the sea of CMB radiation and collide with microwave photons. These collisions boost the energy of the photons up into the X-ray band (purple and white), allowing them to be detected by Chandra even at this great distance, which is shown in the inset.
Researchers, in fact, identified and then confirmed the existence of two different black holes with jets over 300,000 light-years long. The two black holes are 11.6 billion and 11.7 billion light-years away from Earth, respectively. Particles in one jet are moving at between 95% and 99% of the speed of light (called J1405+0415) and in the other at between 92% and 98% of the speed of light (J1610+1811). The jet from J1610+1811 is remarkably powerful, carrying roughly half as much energy as the intense light from hot gas orbiting the black hole.
The team was able to detect these jets despite their great distances and small separation from the bright, growing supermassive black holes — known as “quasars” — because of Chandra’s sharp X-ray vision, and because the CMB was much denser then than it is now, enhancing the energy boost described above.
When quasar jets approach the speed of light, Einstein’s theory of special relativity creates a dramatic brightening effect. Jets aimed toward Earth appear much brighter than those pointed away. The same brightness astronomers observe can come from vastly different combinations of speed and viewing angle. A jet racing at near-light speed but angled away from us can appear just as bright as a slower jet pointed directly at Earth.
The researchers developed a novel statistical method that finally cracked this challenge of separating effects of speed and of viewing angle. Their approach recognizes a fundamental bias: astronomers are more likely to discover jets pointed toward Earth simply because relativistic effects make them appear brightest. They incorporated this bias using a modified probability distribution, which accounts for how jets oriented at different angles are detected in surveys.
Their method works by first using the physics of how jet particles scatter the CMB to determine the relationship between jet speed and viewing angle. Then, instead of assuming all angles are equally likely, they apply the relativistic selection effect: jets beamed toward us (smaller angles) are overrepresented in our catalogs. By running ten thousand simulations that match this biased distribution to their physical model, they could finally determine the most probable viewing angles: about 9 degrees for J1405+0415 and 11 degrees for J1610+1811.
These results were presented by Jaya Maithil (Center for Astrophysics | Harvard & Smithsonian) at the 246th meeting of the American Astronomical Society in Anchorage, AK, and are also being published in The Astrophysical Journal. A preprint is available here. NASA’s Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program. The Smithsonian Astrophysical Observatory’s Chandra X-ray Center controls science operations from Cambridge, Massachusetts, and flight operations from Burlington, Massachusetts.
Read more from NASA’s Chandra X-ray Observatory Learn more about the Chandra X-ray Observatory and its mission here:
https://www.nasa.gov/chandra
https://chandra.si.edu
Visual Description
This release is supported by an artist’s illustration of a jet blasting away from a supermassive black hole.
The black hole sits near the center of the illustration. It resembles a black marble with a fine yellow outline. Surrounding the black hole is a swirling disk, resembling a dinner plate tilted to face our upper right. This disk comprises concentric rings of fiery swirls, dark orange near the outer edge, and bright yellow near the core.
Shooting out of the black hole are two streaky beams of silver and pale violet. One bright beam shoots up toward our upper right, and a second somewhat dimmer beam shoots in the opposite direction, down toward our lower left. These beams are encircled by long, fine, corkscrewing lines that resemble stretched springs.
This black hole is located 11.6 billion light-years from Earth, much earlier in the history of the universe. Near this black hole, the leftover glow from the big bang, known as the cosmic microwave background or CMB, is much denser than it is now. As the electrons in the jets blast away from the black hole, they move through the sea of CMB radiation. The electrons boost the energies of the CMB light into the X-ray band, allowing the jets to be detected by Chandra, even at this great distance.
Inset at our upper righthand corner is an X-ray image depicting this interaction. Here, a bright white circle is ringed with a band of glowing purple energy. The jet is the faint purple line shooting off that ring, aimed toward our upper right, with a blob of purple energy at its tip.
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Lane Figueroa
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By NASA
NASA’s James Webb Space Telescope recently imaged the Sombrero Galaxy with its NIRCam (Near-Infrared Camera), which shows dust from the galaxy’s outer ring blocking stellar light from stars within the galaxy. In the central region of the galaxy, the roughly 2,000 globular clusters, or collections of hundreds of thousands of old stars held together by gravity, glow in the near-infrared. The Sombrero Galaxy is around 30 million light-years from Earth in the constellation Virgo. From Earth, we see this galaxy nearly “edge-on,” or from the side.NASA, ESA, CSA, STScI After capturing an image of the iconic Sombrero galaxy at mid-infrared wavelengths in late 2024, NASA’s James Webb Space Telescope has now followed up with an observation in the near-infrared. In the newest image, released on June 3, 2025, the Sombrero galaxy’s tightly packed group of stars at the galaxy’s center is illuminated while the dust in the outer edges of the disk blocks some stellar light. Studying galaxies like the Sombrero at different wavelengths, including the near-infrared and mid-infrared with Webb, as well as the visible with NASA’s Hubble Space Telescope, helps astronomers understand how this complex system of stars, dust, and gas formed and evolved, along with the interplay of that material.
Learn more about the Sombrero galaxy and what this new view can tell us.
Image credit: NASA, ESA, CSA, STScI
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X-ray: NASA/CXC/CfA/Stroe, A. et al.; Optical: PanSTARRS; Radio: ASTRON/LOFAR; Image Processing: NASA/CXC/SAO/N. Wolk New observations from NASA’s Chandra X-ray Observatory and other telescopes have captured a rare cosmic event: two galaxy clusters have collided and are now poised to head back for another swipe at each other.
Galaxy clusters are some of the largest structures in the Universe. Held together by gravity, they are monster-sized collections of hundreds or thousands of individual galaxies, massive amounts of superheated gas, and invisible dark matter.
The galaxy cluster PSZ2 G181.06+48.47 (PSZ2 G181 for short) is about 2.8 billion light-years from Earth. Previously, radio observations from the LOw Frequency ARray (LOFAR), an antenna network in the Netherlands, spotted parentheses-shaped structures on the outside of the system. In this new composite image, X-rays from Chandra (purple) and ESA’s XMM-Newton (blue) have been combined with LOFAR data (red) and an optical image from Pan-STARRs of the stars in the field of view.
These structures are probably shock fronts — similar to those created by jets that have broken the sound barrier — likely caused by disruption of gas from the initial collision about a billion years ago. Since the collision they have continued traveling outwards and are currently separated by about 11 million light-years, the largest separation of these kinds of structures that astronomers have ever seen.
Colliding galaxy clusters PSZ2 G181.06+48.47 (Labeled).X-ray: NASA/CXC/CfA/Stroe, A. et al.; Optical: PanSTARRS; Radio: ASTRON/LOFAR; Image Processing: NASA/CXC/SAO/N. Wolk Now, data from NASA’s Chandra and ESA’s XMM-Newton is providing evidence that PSZ2 G181 is poised for another collision. Having a first pass at ramming each other, the two clusters have slowed down and begun heading back toward a second crash.
Astronomers made a detailed study of the X-ray observations of this collision site and found three shock fronts. These are aligned with the axis of the collision, and the researchers think they are early signs of the second, oncoming crash.
The researchers are still trying to determine how much mass each of the colliding clusters contains. Regardless, the total mass of the system is less than others where galaxy clusters have collided. This makes PSZ2 G181 an unusual case of a lower-mass system involved in the rare event of colliding galaxy clusters.
A paper describing these results appears in a recent issue of The Astrophysical Journal (ApJ) and is led by Andra Stroe from the Center for Astrophysics | Harvard & Smithsonian (CfA) and collaborators. It is part of a series of three papers in ApJ. The second paper is led by Kamlesh Rajpurohit, also of CfA, and the third paper is led by Eunmo Ahn, from Yonsei University in the Republic of Korea.
NASA’s Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program. The Smithsonian Astrophysical Observatory’s Chandra X-ray Center controls science operations from Cambridge, Massachusetts, and flight operations from Burlington, Massachusetts.
Read more from NASA’s Chandra X-ray Observatory Learn more about the Chandra X-ray Observatory and its mission here:
https://www.nasa.gov/chandra
https://chandra.si.edu
Visual Description
In this release, a composite image illustrates a dramatic cosmic story unfolding 2.8 billion light years from Earth. Presented both with and without labels, the image details the fallout when two galaxy clusters collide.
At the center of the image are the colliding galaxy clusters, which together are known as PSZ2 G181. This combined cluster somewhat resembles an irregular violet peanut shell, with bulbous ends linked by a tapered middle. Inside each bulbous end are several glowing dots; some of the galaxies within the clusters. The violet peanut shape is tilted at a slight angle, surrounded by a blue haze of X-ray gas.
Far from the bulbous ends, at our upper left and lower right, are two blotchy, thick red lines. These are probably shock fronts, similar to those created by jets that have broken the sound barrier. Bracketing the combined galaxy cluster, these shock fronts were caused by the initial collision about a billion years ago. They are currently separated by 11 million light-years.
New data from the Chandra and XMM-Newton observatories suggests that PSZ2 G181 is poised for another powerful cosmic event. Having already taken one swipe at each other, the two clusters within are once again on a collision course.
News Media Contact
Megan Watzke
Chandra X-ray Center
Cambridge, Mass.
617-496-7998
mwatzke@cfa.harvard.edu
Lane Figueroa
Marshall Space Flight Center, Huntsville, Alabama
256-544-0034
lane.e.figueroa@nasa.gov
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Last Updated Jun 04, 2025 Related Terms
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