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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 AI and Hubble Science 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 Observes Noteworthy Nearby Spiral Galaxy
This NASA/ESA Hubble Space Telescope image features the nearby spiral galaxy NGC 2835. ESA/Hubble & NASA, R. Chandar, J. Lee and the PHANGS-HST team This NASA/ESA Hubble Space Telescope image offers a new view of the nearby spiral galaxy NGC 2835, which lies 35 million light-years away in the constellation Hydra (the Water Snake). The galaxy’s spiral arms are dotted with young blue stars sweeping around an oval-shaped center where older stars reside.
This image differs from previously released images from Hubble and the NASA/ESA/CSA James Webb Space Telescope because it incorporates new data from Hubble that captures a specific wavelength of red light called H-alpha. The regions that are bright in H-alpha emission are visible along NGC 2835’s spiral arms, where dozens of bright pink nebulae appear like flowers in bloom. Astronomers are interested in H-alpha light because it signals the presence of several different types of nebulae that arise during different stages of a star’s life. Newborn, massive stars create nebulae called H II regions that are particularly brilliant sources of H-alpha light, while dying stars can leave behind supernova remnants or planetary nebulae that can also be identified by their H-alpha emission.
By using Hubble’s sensitive instruments to survey 19 nearby galaxies, researchers aim to identify more than 50,000 nebulae. These observations will help to explain how stars affect their birth neighborhoods through intense starlight and winds.
Text Credit: ESA/Hubble
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Last Updated Aug 21, 2025 Editor Andrea Gianopoulos Location NASA Goddard Space Flight Center Related Terms
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Preparations for Next Moonwalk Simulations Underway (and Underwater)
Dwarf planet Ceres is shown in these enhanced-color renderings that use images from NASA’s Dawn mission. New thermal and chemicals models that rely on the mission’s data indicate Ceres may have long ago had conditions suitable for life.NASA/JPL-Caltech/UCLA/MPS/DLR/IDA The dwarf planet is cold now, but new research paints a picture of Ceres hosting a deep, long-lived energy source that may have maintained habitable conditions in the past.
New NASA research has found that Ceres may have had a lasting source of chemical energy: the right types of molecules needed to fuel some microbial metabolisms. Although there is no evidence that microorganisms ever existed on Ceres, the finding supports theories that this intriguing dwarf planet, which is the largest body in the main asteroid belt between Mars and Jupiter, may have once had conditions suitable to support single-celled lifeforms.
Science data from NASA’s Dawn mission, which ended in 2018, previously showed that the bright, reflective regions on Ceres’ surface are mostly made of salts left over from liquid that percolated up from underground. Later analysis in 2020 found that the source of this liquid was an enormous reservoir of brine, or salty water, below the surface. In other research, the Dawn mission also revealed evidence that Ceres has organic material in the form of carbon molecules — essential, though not sufficient on its own, to support microbial cells.
The presence of water and carbon molecules are two critical pieces of the habitability puzzle on Ceres. The new findings offer the third: a long-lasting source of chemical energy in Ceres’ ancient past that could have made it possible for microorganisms to survive. This result does not mean that Ceres had life, but rather, that there likely was “food” available should life have ever arisen on Ceres.
This illustration depicts the interior of dwarf planet Ceres, including the transfer of water and gases from the rocky core to a reservoir of salty water. Carbon dioxide and methane are among the molecules carrying chemical energy beneath Ceres’ surface.NASA/JPL-Caltech In the study, published in Science Advances on Aug. 20, the authors built thermal and chemical models mimicking the temperature and composition of Ceres’ interior over time. They found that 2.5 billion years or so ago, Ceres’ subsurface ocean may have had a steady supply of hot water containing dissolved gases traveling up from metamorphosed rocks in the rocky core. The heat came from the decay of radioactive elements within the dwarf planet’s rocky interior that occurred when Ceres was young — an internal process thought to be common in our solar system.
“On Earth, when hot water from deep underground mixes with the ocean, the result is often a buffet for microbes — a feast of chemical energy. So it could have big implications if we could determine whether Ceres’ ocean had an influx of hydrothermal fluid in the past,” said Sam Courville, lead author of the study. Now based at Arizona State University in Tempe, he led the research while working as an intern at NASA’s Jet Propulsion Laboratory in Southern California, which also managed the Dawn mission.
Catching Chill
The Ceres we know today is unlikely to be habitable. It is cooler, with more ice and less water than in the past. There is currently insufficient heat from radioactive decay within Ceres to keep the water from freezing, and what liquid remains has become a concentrated brine.
The period when Ceres would most likely have been habitable was between a half-billion and 2 billion years after it formed (or about 2.5 billion to 4 billion years ago), when its rocky core reached its peak temperature. That’s when warm fluids would have been introduced into Ceres’ underground water.
The dwarf planet also doesn’t have the benefit of present-day internal heating generated by the push and pull of orbiting a large planet, like Saturn’s moon Enceladus and Jupiter’s moon Europa do. So Ceres’ greatest potential for habitability-fueling energy was in the past.
This result has implications for water-rich objects throughout the outer solar system, too. Many of the other icy moons and dwarf planets that are of similar size to Ceres (about 585 miles, or 940 kilometers, in diameter) and don’t have significant internal heating from the gravitational pull of planets could have also had a period of habitability in their past.
More About Dawn
A division of Caltech in Pasadena, JPL managed Dawn’s mission for NASA’s Science Mission Directorate in Washington. Dawn was a project of the directorate’s Discovery Program, managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama. JPL was responsible for overall Dawn mission science. Northrop Grumman in Dulles, Virginia, designed and built the spacecraft. The German Aerospace Center, Max Planck Institute for Solar System Research, Italian Space Agency and Italian National Astrophysical Institute were international partners on the mission team.
For a complete list of mission participants, visit:
https://solarsystem.nasa.gov/missions/dawn/overview/
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Gretchen McCartney
Jet Propulsion Laboratory, Pasadena, Calif.
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Last Updated Aug 20, 2025 Related Terms
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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 AI and Hubble Science 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 Examines Low Brightness, High Interest Galaxy
This NASA/ESA Hubble Space Telescope image features a portion of the spiral galaxy NGC 45. ESA/Hubble & NASA, D. Calzetti, R. Chandar; Acknowledgment: M. H. Özsaraç This NASA/ESA Hubble Space Telescope image zooms in on the feathery spiral arms of the galaxy NGC 45, which lies just 22 million light-years away in the constellation Cetus (the Whale).
The portrait uses data drawn from two complementary observing programs. The first took a broad view of 50 nearby galaxies, leveraging Hubble’s ability to observe ultraviolet through visible into near-infrared light to study star formation in these galaxies. The second program examined many of the same nearby galaxies as the first, narrowing in on a particular wavelength of red light called H-alpha. Star-forming nebulae are powerful producers of H-alpha light, and several of these regions are visible across NGC 45 as bright pink-red patches.
These observing programs aimed to study star formation in galaxies of different sizes, structures, and degrees of isolation — and NGC 45 is a particularly interesting target. Though it may appear to be a regular spiral galaxy, NGC 45 is a remarkable type called a low surface brightness galaxy.
Low surface brightness galaxies are fainter than the night sky itself, making them incredibly difficult to detect. They appear unexpectedly faint because they have relatively few stars for the volume of gas and dark matter they carry. In the decades since astronomers serendipitously discovered the first low surface brightness galaxy in 1986, researchers have learned that 30–60% of all galaxies may fall into this category. Studying these hard-to-detect galaxies is key to understanding how galaxies form and evolve, and Hubble’s sensitive instruments are equal to the task.
Text Credit: ESA/Hubble
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Last Updated Aug 14, 2025 Editor Andrea Gianopoulos Location NASA Goddard Space Flight Center Related Terms
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Explore Hubble Science Hubble Space Telescope NASA’s Hubble Uncovers Rare… 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 AI and Hubble Science 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 5 min read
NASA’s Hubble Uncovers Rare White Dwarf Merger Remnant
This is an illustration of a white dwarf star merging into a red giant star. A bow shock forms as the dwarf plunges through the star’s outer atmosphere. The passage strips down the white dwarf’s outer layers, exposing an interior carbon core. Artwork: NASA, ESA, STScI, Ralf Crawford (STScI) An international team of astronomers has discovered a cosmic rarity: an ultra-massive white dwarf star resulting from a white dwarf merging with another star, rather than through the evolution of a single star. This discovery, made by NASA’s Hubble Space Telescope’s sensitive ultraviolet observations, suggests these rare white dwarfs may be more common than previously suspected.
“It’s a discovery that underlines things may be different from what they appear to us at first glance,” said the principal investigator of the Hubble program, Boris Gaensicke, of the University of Warwick in the United Kingdom. “Until now, this appeared as a normal white dwarf, but Hubble’s ultraviolet vision revealed that it had a very different history from what we would have guessed.”
A white dwarf is a dense object with the same diameter as Earth, and represents the end state for stars that are not massive enough to explode as core-collapse supernovae. Our Sun will become a white dwarf in about 5 billion years.
In theory, a white dwarf can have a mass of up to 1.4 times that of the Sun, but white dwarfs heavier than the Sun are rare. These objects, which astronomers call ultra-massive white dwarfs, can form either through the evolution of a single massive star or through the merger of a white dwarf with another star, such as a binary companion.
This new discovery, published in the journal Nature Astronomy, marks the first time that a white dwarf born from colliding stars has been identified by its ultraviolet spectrum. Prior to this study, six white dwarf merger products were discovered via carbon lines in their visible-light spectra. All seven of these are part of a larger group that were found to be bluer than expected for their masses and ages from a study with ESA’s Gaia mission in 2019, with the evidence of mergers providing new insights into their formation history.
Astronomers used Hubble’s Cosmic Origins Spectrograph to investigate a white dwarf called WD 0525+526. Located 128 light-years away, it is 20% more massive than the Sun. In visible light, the spectrum of WD 0525+526’s atmosphere resembled that of a typical white dwarf. However, Hubble’s ultraviolet spectrum revealed something unusual: evidence of carbon in the white dwarf’s atmosphere.
White dwarfs that form through the evolution of a single star have atmospheres composed of hydrogen and helium. The core of the white dwarf is typically composed mostly of carbon and oxygen or oxygen and neon, but a thick atmosphere usually prevents these elements from appearing in the white dwarf’s spectrum.
When carbon appears in the spectrum of a white dwarf, it can signal a more violent origin than the typical single-star scenario: the collision of two white dwarfs, or of a white dwarf and a subgiant star. Such a collision can burn away the hydrogen and helium atmospheres of the colliding stars, leaving behind a scant layer of hydrogen and helium around the merger remnant that allows carbon from the white dwarf’s core to float upward, where it can be detected.
WD 0525+526 is remarkable even within the small group of white dwarfs known to be the product of merging stars. With a temperature of almost 21,000 kelvins (37,000 degrees Fahrenheit) and a mass of 1.2 solar masses, WD 0525+526 is hotter and more massive than the other white dwarfs in this group.
WD 0525+526’s extreme temperature posed something of a mystery for the team. For cooler white dwarfs, such as the six previously discovered merger products, a process called convection can mix carbon into the thin hydrogen-helium atmosphere. WD 0525+526 is too hot for convection to take place, however. Instead, the team determined a more subtle process called semi-convection brings a small amount of carbon up into WD 0525+526’s atmosphere. WD 0525+526 has the smallest amount of atmospheric carbon of any white dwarf known to result from a merger, about 100,000 times less than other merger remnants.
The high temperature and low carbon abundance mean that identifying this white dwarf as the product of a merger would have been impossible without Hubble’s sensitivity to ultraviolet light. Spectral lines from elements heavier than helium, like carbon, become fainter at visible wavelengths for hotter white dwarfs, but these spectral signals remain bright in the ultraviolet, where Hubble is uniquely positioned to spot them.
“Hubble’s Cosmic Origins Spectrograph is the only instrument that can obtain the superb quality ultraviolet spectroscopy that was required to detect the carbon in the atmosphere of this white dwarf,” said study lead Snehalata Sahu from the University of Warwick.
Because WD 0525+526’s origin was revealed only once astronomers glimpsed its ultraviolet spectrum, it’s likely that other seemingly “normal” white dwarfs are actually the result of cosmic collisions — a possibility the team is excited to explore in the future.
“We would like to extend our research on this topic by exploring how common carbon white dwarfs are among similar white dwarfs, and how many stellar mergers are hiding among the normal white dwarf family,” said study co-leader Antoine Bedrad from the University of Warwick. “That will be an important contribution to our understanding of white dwarf binaries, and the pathways to supernova explosions.”
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, 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 Hubble, visit: https://science.nasa.gov/hubble
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Last Updated Aug 13, 2025 Editor Andrea Gianopoulos Location NASA Goddard Space Flight Center Contact Media Claire Andreoli
NASA’s Goddard Space Flight Center
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claire.andreoli@nasa.gov
Ray Villard
Space Telescope Science Institute
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ESA/Hubble
Garching, Germany
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Science Paper: A hot white dwarf merger remnant revealed by an ultraviolet detection of carbon, PDF (23.45 MB)
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This NASA/ESA Hubble Space Telescope image shows a portion of the Tarantula Nebula.ESA/Hubble & NASA, C. Murray This NASA/ESA Hubble Space Telescope image captures incredible details in the dusty clouds of a star-forming factory called the Tarantula Nebula. Most of the nebulae Hubble images are in our galaxy, but this nebula is in the Large Magellanic Cloud, a dwarf galaxy located about 160,000 light-years away in the constellations Dorado and Mensa.
The Large Magellanic Cloud is the largest of the dozens of small satellite galaxies that orbit the Milky Way. The Tarantula Nebula is the largest and brightest star-forming region, not just in the Large Magellanic Cloud, but in the entire group of nearby galaxies to which the Milky Way belongs.
The Tarantula Nebula is home to the most massive stars known, some roughly 200 times as massive as our Sun. This image is very close to a rare type of star called a Wolf–Rayet star. Wolf–Rayet stars are massive stars that have lost their outer shell of hydrogen and are extremely hot and luminous, powering dense and furious stellar winds.
This nebula is a frequent target for Hubble, whose multiwavelength capabilities are critical for capturing sculptural details in the nebula’s dusty clouds. The data used to create this image come from an observing program called Scylla, named for a multi-headed sea monster from Greek mythology. The Scylla program was designed to complement another Hubble observing program called ULLYSES (Ultraviolet Legacy Library of Young Stars as Essential Standards). ULLYSES targets massive young stars in the Small and Large Magellanic Clouds, while Scylla investigates the structures of gas and dust that surround these stars.
Image credit: ESA/Hubble & NASA, C. Murray
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