A catalog of almost 3,000 white dwarfs that exploded as type Ia supernovas after overfeeding on companion stars indicates that dark energy, the mysterious force accelerating the expansion of the universe, is changing over time.
The discovery, in conjunction with data from the Dark Energy Survey (DES), backs results revealed from the Dark Energy Spectroscopic Instrument (DESI) published in 2024 that suggested dark energy's influence is weakening.
That means that the team's research doesn't just involve the most comprehensive catalog of type Ia supernovas; it presents the clearest picture yet of the evolution of the universe and the influence of dark energy.
"We've rebuilt 3 decades of astronomical observations into a single, consistent framework," team member Ryan Camilleri of the University of Queensland said in a statement."We combined our data with other cosmic measurements, including relic light from the Big Bang and maps of how galaxies are distributed through space.
"Instead of confirming the standard model of cosmology, which assumes dark energy is fixed and unchanging, we have more evidence that dark energy may change over time."
White dwarfs are the smoldering stellar remnants that are left over when stars with around the mass of the sun exhaust the fuel for nuclear fusion in their cores. This ends the outward pressure that supports a star against its own gravity, meaning the star's core collapses as the outer layers are shed. The core becomes a white dwarf, and for single stars, that is the end. But around 50% of sun-sized stars have a binary companion, and this can lead to renewed activity and a change in the star's fate.
If the white dwarf and its companion are close enough together, the dead star begins stripping away the outer layers of its companion. As this material builds on the white dwarf, it pushes the stellar remnant's mass over the so-called Chandrasekhar limit, allowing it to go supernova.
These cosmic explosions are called type Ia supernovas, and their light output is so uniform that these events are referred to as standard candles. They are of vital importance because measuring how their light has been redshifted as it travels means type Ia supernovas can be used to measure cosmic distances.
"Over the years we've learned a lot more about how supernovae behave so we've been able to go back and apply that improved understanding to older data," Camilleri said. "Extensive work has been done to link observations from different telescopes with different capacities and take into account issues such as cosmic dust and galaxy mass which can affect the light coming from a supernova.
"We also incorporated more subtle effects such as gravitational lensing, which is the bending and magnification of light around large objects as it travels from a supernova to Earth."
Combined with the 2024 results from DESI, this research could change our idea of what dark energy actually is.
"Our supernova data from DES in 2024 first showed hints that dark energy may be time-varying, and this new compilation also sees a deviation from the standard model, although in a slightly different direction," Davis said. "Similarly, results from DESI found hints of variations in dark energy in its surveys of relic sound waves from the early universe.
"So, two completely independent measurements have found hints of time variation in dark energy, challenging the standard model that dark energy doesn't change."
Davis added that, as well as revealing what dark energy actually is, this research may also hold the clue to explaining how gravity and quantum physics fit together. While quantum physics (the best theory we have of how the universe operates at subatomic scales) and Einstein's theory of general relativity (our best picture of gravity) have been highly successful in their own rights, scientists have so far been unable to unite them. In other words, there is no theory of quantum gravity.
“We know these two theories are each immensely successful in their own realms, so if we can figure out how to put them together, that would be a huge step in theoretical physics," Davis continued.
This effort will receive a boost when data is added to the team's already comprehensive type Ia supernova catalog. This will include observations from the Dark Energy Bedrock All-Sky Supernova program (DEBASS), which is detecting hundreds more local supernovas than even the DES survey.
The team's results are available on the repository site arXiv.
Physicists around the world remain deeply divided on key mysteries of the universe, from dark matter to quantum gravity. The standard cosmological model failed to gain majority support, and no leading theory dominated the survey results. The largest survey ever conducted among physicists worldwide reveals surprisingly little agreement on some of the field’s biggest mysteries, [...]Astronomers have combined 2,884 Type Ia supernovae -- which are used to measure cosmic distances -- with cosmic microwave background and galaxy-mapping data, deepening cracks in the standard ‘cosmological constant’ model.
The post Dark Energy May Not Be Constant After All, New Supernova Survey Suggests appeared first on Sci.News: Breaking Science News.
In the 1970s, astronomer Vera Rubin analyzed a series of observations of how quickly different galaxies rotated around their centers. She found that these galaxies rotated much faster than they should have, given the amount of material visible through starlight. She concluded that a large fraction of these galaxies’ masses must therefore consist of some kind of unseen material.
Scientists have since observed galaxies to more precisely measure this unseen material, which they now call dark matter. They’ve shown that dark matter moves much more slowly than the speed of light. Unlike most celestial objects, it can’t emit or block any light, meaning it doesn’t interact with the electromagnetic force. Even though it doesn’t interact with a fundamental force in the universe, dark matter constitutes over 80% of the mass of an average galaxy.
In the prevailing model of cosmology, known as ΛCDM (pronounced “Lambda-CDM”), dark matter determined where galaxies formed. The theory is that gravity pulled dark matter together more quickly than regular matter in the primordial universe. This redistribution led to regions of space with greater mass density, which collected chaotic, regular matter into pools that eventually formed galaxies, stars, and planets.
In the present universe, dark matter and regular matter coexist in galaxies, though generally separated. Regular matter pools in the very center of galaxies, forming the more familiar galactic disks. Dark matter stays towards the edges of galaxies, enveloping the regular matter disks in what are known as dark matter halos. Because these halos make up so much of the mass of the average galaxy, researchers Guangze Sun, Fangzhou Jiang, and Jing Wang conducted a series of simulations to test how dark matter halos affect regular matter in galaxies. Specifically, they examined what characteristics of dark matter halos determine galaxy sizes.
The force of gravity works such that more massive dark matter halos draw in more regular matter and produce larger galaxies. So these researchers fixed the total mass of the galaxies they simulated at 100 billion times that of the Sun to determine which properties of the dark matter halos would produce the widest galaxies. They selected 4 variables to test: the total density of dark matter in the galactic halo, the density of dark matter in the innermost 1% of the halo, how fast the halo spun, and the ratio of regular matter to dark matter in the entire galaxy. For each variable, they tested 3 to 4 inputs representing low, moderate, and high values against a standard reference value and ran 132 total simulations to generate enough data for statistical analyses.
To simulate the complex physics of dark matter halos, the team used the modeling software GIZMO to model gravity, magnetism, and fluid dynamics. They combined this with a second model, called FIRE-3, which modeled how stars explode at the end of their lives, how much metal these explosions produce, and how gases heat up and cool down over time. The researchers ran the dynamic simulations for 3 billion model years, then used a program they developed based on the existing Pynbody to measure the radii of the simulated galaxies.
The team found that the faster a dark matter halo spun around a simulated galaxy, the larger the galaxy became, as shown in scenario 1 in the figure below. By contrast, in scenario 2, increasing the halo’s total dark matter concentration caused the central galaxy to shrink. Increasing only the innermost dark matter density in the halo had a smaller effect but generally reduced the galaxy’s size, as shown in scenario 3. And lastly, increasing the ratio of regular matter to dark matter in galaxies resulted in smaller galaxies that formed stars closer to their centers, as shown by a greater concentration of stars in scenario 4.
This diagram showcases the team’s results across 4 broad scenarios. The left column depicts a default galaxy under the baseline parameters. The right column depicts how the galaxies changed when the team varied a single experimental factor, including 1) increasing how fast the dark matter halo spun, 2) increasing the total density of the dark matter halo, 3) increasing the density of dark matter in the innermost halo, and 4) increasing the ratio of regular matter to dark matter in the entire galaxy. The dark matter haloes are represented as red rings surrounding the galaxies, not to scale. Illustration by Andrew Bizal.
The team’s results suggest a previously unknown connection between the properties of dark matter halos and galactic disks. However, they cautioned that their simulations were all run on galaxies in isolation, unlike in the actual ΛCDM universe, where their interactions are complicated by galaxies tugging on one another or by material moving from one to another. To further test their results for single galaxies, the researchers plan to run follow-up experiments with halos of different sizes, as well as with galaxies with different shapes and features, such as clumps, gaps, and lopsidedness.
The post Dark matter influences the size of galaxies appeared first on Sciworthy.
James Webb Space Telescope (JWST) data have revealed hidden stars that astronomers say are unexpectedly increasing the mass of early galaxies.
JWST‘s ability to see deep into the cosmos gives astronomers insight into the early universe and challenges prior expectations of what they would find there. Now, an international team led by astronomers from the Netherlands’ Leiden University recently reported the discovery of new stars in a paper published in Nature Astronomy.
With the discovery of these many previously unknown small stars, the researchers say astronomers may need to reconsider the expected mass of these early galaxies, as JWST reveals unexpected levels of development shortly after the Big Bang.
For their new work, the astronomers focused on nine massive galaxies in the early universe that had completed their main star-formation period. They combined JWST data with earlier observations from the Very Large Telescope in Chile, operated by the European Southern Observatory.
Spectroscopy is a crucial element of JWST data, breaking light down into separate spectra that allow astronomers to study stars and even planetary atmospheres across extreme distances. However, the smaller, fainter stars revealed in this new research can be much harder to detect than the brighter, more powerful ones.
“If a galaxy were a city, the brightest stars would be the skyscrapers you can immediately see from far away,” said first author Chloe Cheng. “Our models show that behind the brightest stars there is a much larger population of small stars, like houses among the skyscrapers. This means that the galaxy as a whole is much more massive than previous estimates suggested.”
Working with data limited by the sensitivity of tools, researchers previously were unable to see as many smaller stellar objects. Researchers then assumed a similar ratio of small to large stars across the universe, which these new findings are now challenging.
Instead, they found ancient massive galaxies filled with many more small stars than previously expected, and far more than in our own Milky Way galaxy today, which is a smaller galaxy. The mass differences produced by this glut of tiny stars increased the expected mass of the galaxy under 1.5 billion years old by fourfold.
“Measurements like these were simply not possible until recently,” explained co-author Martje Slob. “We needed not only a telescope capable of collecting enough light, but also exceptionally high-quality spectra and new analysis techniques. Only then could we reliably distinguish the subtle features of small stars from the light of much brighter stars.”
Launched almost five years ago, JWST has continually defied what astronomers expected to find in the ancient universe. It turns out that the universe shortly after the Big Bang was more massive and had undergone more development than previously considered possible. The new findings add to those ongoing discoveries.
“This result shows that much more mass than we thought is hidden in small stars,” said study lead Professor Mariska Kriek. “It has implications for many areas of astronomy. Small stars often have planets orbiting them, so if there were many more small stars in the early Universe than we thought, there may also have been more planets.”
To follow up on this exciting discovery, the team plans to look even further back into the universe’s past in future observations that will study some of the universe’s very earliest stars.
The paper, “Hidden Mass in Early Galaxies Revealed by Bottom-Heavy Initial Mass Functions,” appeared in Nature Astronomy on August 18, 2026.
Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org.
Editor’s Note: Astrobites is a graduate-student-run organization that digests astrophysical literature for undergraduate students. As part of the partnership between the AAS and astrobites, we occasionally repost astrobites content here at AAS Nova. We hope you enjoy this post from astrobites; the original can be viewed at astrobites.org.
Title: Unbreaking the Universe: MINERVA Measurements of Color Gradients in Massive Quiescent Galaxies Can Help Ease Too-Early Star Formation Tensions
Authors: Sam E. Cutler et al.
First Author’s Institution: Tufts University
Status: Published in ApJL
JWST launched in 2021, and one of its key goals was to observe the first galaxies as they formed. Early results from JWST found something surprising: extremely massive galaxies in the early universe that had “quenched,” or stopped making new stars, much faster than was expected. These early results led some to believe that our understanding of how quickly massive galaxies can form and quench was fundamentally wrong.
Before concluding that our understanding of the universe is broken, it’s important to find other reasons why we might see very massive galaxies in the early universe. One theory is that these galaxies are actually less massive than we think. To “weigh” a galaxy, astronomers first measure the amount of light being emitted by that galaxy. If all the light in a galaxy comes from stars (which should be true in the early universe, though active black holes can contribute a lot of light in some galaxies), you can infer the total number of stars by accounting for the average amount of light emitted per star of a certain mass; this is called the “mass-to-light ratio.” Since massive stars emit a lot more light than low-mass stars, and high-mass stars die out faster than low-mass stars, the mass-to-light ratio is higher for older stellar populations. To accurately “weigh” a galaxy, scientists therefore need both a good measurement of the total amount of light in the galaxy and how old its stellar population is. The authors of today’s article suggest that the uncertainty in these measurements might be leading to overestimates of galaxy masses and underestimates of galaxy star formation rates, possibly explaining the existence of the earliest massive quiescent (non-star-forming) galaxies.
Previous works about the massive quiescent galaxies in this study used spectroscopy to determine the galaxies’ masses and star formation rates. These spectra were taken with a “slit,” which introduces a source of error: if the slit is smaller than the image of the galaxy, some of the galaxy’s light will be missed in the spectrum. Astronomers usually correct for this by checking how much of the total light of a galaxy image is covered by the slit and scaling up the spectrum to account for the missing light, but this correction assumes that the spectrum is basically the same across the entire galaxy.
However, this assumption is rarely correct. In the local universe, star-forming spiral galaxies like the Milky Way tend to be made of a central “bulge” surrounded by a “disk” (see Figure 1). The bulge is no longer actively forming new stars, leading to a red-to-blue color gradient as you move out from the center of the galaxy. In astronomy, this is considered a “negative” color gradient. A slit that only covers the galaxy center would lead to an overall overestimate of the stellar mass and underestimate of the star formation rate. If the galaxies instead had a positive color gradient, with more star formation in the center of the galaxy, the mass would be underestimated and the star formation rate would be overestimated. Galaxies with both positive and negative color gradients have been found in the distant universe. By measuring the color gradient for each individual galaxy in their sample, the authors can correct the mass and star formation rate calculations from spectra taken with a slit spectrograph.
Figure 1: The spiral galaxy NGC 2683 with its bulge and disk labeled. The inner part of the galaxy (“bulge”) contains older, redder stars; the outer part of the galaxy (“disk”) contains bright blue stars that indicate that star formation is ongoing. Here, the slit spectrograph only covers the galaxy’s bulge, leading to incorrect mass and star formation rate measurements. [ESA/Hubble & NASA (CC BY 4.0) with annotations by Margaret Verrico]
Instead of using spectra, the authors of today’s article use imaging in different filters to measure color gradients for a sample of four galaxies in the early universe that had previously been found to be extremely massive and no longer forming stars. They use medium-band filters, or filters that let in only a small part of a galaxy’s spectrum, to produce a spectral energy distribution at each radius. This spectral energy distribution is less informative than a spectrum (think a handprint versus a fingerprint), but it’s detailed enough to model the likely stellar population at each radius to determine whether the galaxies have positive, negative, or no color gradients, allowing for better corrections to the properties measured from the galaxies’ centers. They also model the stellar population from the central part of the galaxy that would normally be covered by a slit, as well as from the actual spectrum, to test whether any differences in their results come from their choice of modeling techniques.
The authors find that three of the four galaxies have a negative color gradient in at least some areas. The fourth galaxy has a relatively flat color gradient, though this measurement is less certain due to the object’s redshift. When the authors plot the galaxies’ colors on a diagnostic diagram that separates red and old galaxies from young and blue galaxies, they find that three of the four galaxies have centers that appear red and old but outskirts that appear young and blue (Figure 2). This means previous measurements of the mass may have been overestimated, and previous measurements of the star formation rate may have been underestimated.
Figure 2: The location of each of the four galaxies on a color–color diagram that separates red galaxies (above/to the left of the dashed lines) from blue galaxies (below/to the right of the dashed lines). The open markers indicate the galaxy color as measured from the center of the galaxy; the filled-in markers show the color at different radii from the galaxy center. For all but one galaxy, the color at several radii is bluer than at the center, indicating that the galaxy might have younger stars at least at some radii. [Adapted from Cutler et al. 2026]
To determine whether these galaxies still count as “universe breakers,” the authors use a cosmological model to predict the largest expected galaxy mass in the observed area at different periods in cosmic time. The previous results had less than a 0.3% chance of occurring under current cosmological models; with their updated numbers and stellar population models, the authors find that the observed galaxies sometimes have more than a 5% chance of occurring, though there is still tension. They point out that their analysis ignores processes that could help galaxies grow and quench in the early universe, like galaxy mergers; still, the existence of these massive galaxies with such low star formation rates remains a puzzle.
Original astrobite edited by Ansh Gupta.
About the author, Margaret Verrico:
I am a fourth-year graduate student at the University of Illinois Urbana-Champaign. I study the connection between supermassive black hole transients and their host galaxies. I am also an avid knitter and reader, and I am passionate about opening up STEM opportunities for people of all backgrounds.
The post Galaxies of Many Colors appeared first on AAS Nova.
Like a collage made of layered sheets of colored cellophane, a vibrant new image layers observations of a famous star-forming nebula from NASA space telescopes. The resulting cosmic “craft” reveals new details about the star formation region known as 30 Doradus, or the Tarantula Nebula.
Located in the Large Magellanic Cloud, a small neighbor galaxy to the Milky Way about 160,000 light-years from Earth, the Tarantula has thousands of young stars embedded in a vibrant honeycomb-like structure of gas and dust.
Like a collage made of layered sheets of colored cellophane, a vibrant new image layers observations of a famous star-forming nebula from NASA space telescopes. The resulting cosmic “craft” reveals new details about the star formation region known as 30 Doradus, or the Tarantula Nebula.
Located in the Large Magellanic Cloud, a small neighbor galaxy to the Milky Way about 160,000 light-years from Earth, the Tarantula has thousands of young stars embedded in a vibrant honeycomb-like structure of gas and dust.
The new composite image contains X-rays from NASA’s Chandra X-ray Observatory, which has repeatedly observed the Tarantula Nebula over the course of its mission, in the layer that appears in blue. The X-ray data reveals gas blown away by winds from the surfaces of young, massive stars and heated to millions of degrees by shock waves, like sonic booms from supersonic jets.
The red represents infrared data from NASA’s James Webb Space Telescope showing thousands of young stars, plus swaths of cool dust that will provide the ingredients to form new stars and planets. Optical data in the green layer from NASA’s Hubble Space Telescope uncovers hydrogen gas that is warmer than seen with Webb, as well as some individual stars through the nebula.
The composite image shows the full Hubble and Webb images of this region, as well as a large section of the Chandra image, all recently published in a research paper in the Astrophysical Journal. In some regions the blue Chandra layer stands alone, and in others it combines with either the red Webb data or the green Hubble data. In the middle region all three images overlap to provide a holistic view in red, orange, yellow, green, and blue.
Previously, astronomers had studied the amount and the impact of energy produced by winds from young, massive stars in the Tarantula Nebula. Scientists expect that much of this energy should heat gas so that it produces X-rays. However, the research paper shows that there is much less X-ray-emitting gas in the nebula than expected. This led researchers to ask: Where has this energy gone and what tamed the Tarantula Nebula?
By studying the data from Chandra, Hubble, and Webb, combined with data from NASA’s retired Spitzer Space Telescope, the team concluded the Tarantula may be losing energy from several sources.
First, up to half of the hot gas is leaking through the shell walls of the gas and dust structures and escaping the nebula. Next, there is stirring and mixing between the cold gas near the shell walls and some of the hot gas, lowering the overall temperature of the gas. Finally, comparisons with computer simulations suggest the Tarantula may be losing energy through conduction. This involves direct physical contact between hot and cooler material, like with a frying pan on a burner, causing the hot and cooler material to equalize in temperature. In the case of the Tarantula Nebula, the hot gas would be conducting heat by being in direct contact with the cooler gas in the shells, especially in the densest regions. This scenario does not necessarily involve mixing the hot and cooler gas.
The combination of these three channels for losing large amounts of energy leads to this colorful and complex display revealed by NASA’s telescopes working together.
The paper describing these results was led by Jennifer Rodriguez of The Ohio State University in Columbus. Additional authors on the paper include Laura Lopez, Ohio State; Lachlan Lancaster, Columbia University in New York City; Anna Rosen, San Diego State University; Omnaraynai Nayak, Space Telescope Science Institute in Baltimore; Sebastian Lopez, Ohio State; Tyler Holland-Ashford, NASA’s Goddard Space Flight Center in Greenbelt, Maryland; and Trinity Webb, Ohio State.
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.
To learn more about Chandra, visit:
The Chandra X-ray Observatory is the world’s most powerful X-ray telescope.
Since its 1990 launch, the Hubble Space Telescope has changed our fundamental understanding of the universe.
Webb is the premier observatory of the next decade, serving thousands of astronomers worldwide. It studies every phase in the…
Universe
O leaker conhecido como Ice Universe [@UniverseIce] publicou ontem no X imagens do que seriam películas para a tela externa do “iPhone Ultra”, o vindouro primeiro smartphone dobrável da Apple.
Como é possível notar, as imagens trazem duas variações do acessório: uma versão completamente transparente e outra com aquele efeito que limita os ângulos de visualização do display para uma maior privacidade.
This is the screen protector for the iPhone Ultra. You can see, the iPhone Ultra actually has an irregular screen with one side square and the other round. Oh my God, can you even handle that? pic.twitter.com/qpQHZHiqcD
— Ice Universe (@UniverseIce) August 11, 2026
O detalhe mais importante aqui, no entanto, é o formato das películas, que conta com cantos retos em um lado e arredondados no outro, dando a entender que o foldable da Maçã terá um design assimétrico.
Em uma outra postagem, desta vez com um vídeo da suposta película, no entanto, Ice Universe disse acreditar que isso se trata de um mal-entendido. Para ele, o mais provável é que a tela do “iPhone Ultra” tenha, sim, cantos arredondados em todas as extremidades, já que a película segue o formato do painel de vidro — e ele não precisa ter necessariamente o formato do display em si, já que se trata de componentes diferentes.
I'm sure this is just a misunderstanding – the protective film covers the entire glass panel, not exactly the same as the actual screen display area. The iPhone Ultra screen itself is still a symmetrical rounded rectangle. pic.twitter.com/Iwu52050uw
— Ice Universe (@UniverseIce) August 11, 2026
O vídeo compartilhado pelo leaker até mostra um mockup do dispositivo com uma tela assimétrica, mas é bem possível que seu criador tenha seguido esse caminho simplesmente por não saber como o smartphone realmente se parecerá.
De qualquer forma, não deverá demorar muito para que essa dúvida seja sanada, uma vez que os rumores são de que a Apple anunciará o “iPhone Ultra” no comecinho de setembro. Ansiosos? 🙂
via GSMArena.com
Observing across the starry “plains” of space, NASA’s James Webb Space Telescope has taken new images of NGC 2392, nicknamed the Lion Nebula. NASA’s Hubble Space Telescope previously viewed this planetary nebula in 2000, imaging the lion face-shaped target in visible light and revealing features such as the “mane” of hazy, comet-shaped objects. Now Webb has captured a clearer, more detailed view of the Lion Nebula due to its high-resolution imaging.
At first glance the nebula’s overall structure in Webb’s infrared images, with both the NIRCam (Near Infrared Camera) and MIRI (Mid Infrared Instrument) instruments, may look quite similar to Hubble’s earlier visible-light view. However, Webb’s infrared vision highlights features like compact clumps of dust and a haze of ionized gas. It’s taken several thousand years for this collection of gas and dust to reach its current shape, and the nebula’s components continue to be altered.
The source of these constant changes and the reason for the Lion Nebula’s distinct appearance is located at the center: the remains of a dying star. Though it looks like the button nose of the lion, its energy and radiation are powering the intricate structures seen here.
Massive stars undergo supernova explosions at the end of their lives, but these kinds of events are few and far in between. Most of the universe’s stars have lower masses, like the one belonging to NGC 2392. When a lower-mass star can no longer sustain itself with nuclear reactions in its core, the star becomes unstable and pulsates, losing its mass by shedding its outer layers, which then turn into shells of gas and dust called a planetary nebula. (Stars at this life stage are responsible for producing much of the universe’s observable dust.) The star’s radiation drives the ejected material away, leaving behind the very hot stellar core, also known as a white dwarf.
In the Lion Nebula’s case, the death of the oxygen-rich central star has left behind a white dwarf that is “cooking” everything from the inside and producing a bubble of ionized gas as it does. The gas bubble, which forms the lion’s face, is expanding over time and destroying dust that is in its path. Understanding why the swept-up gas has a complex structure of rings and shells, a common feature in planetary nebulae, is an ongoing endeavor.
The mane of the lion is the interior of a dust shell that is being illuminated by the white dwarf at the center. The tufts of hair, which look like cometary tails of material, are compact clumps of dust that have survived the stellar core’s radiation and protect the material that lies behind them.
Webb’s imagery “freezes” this planetary nebula in time, though the star’s death, and its tumultuous effects, go on. NGC 2392 will continue to undergo changes as its gas and dust migrate away from the stellar core. Astronomers estimate the lion will eventually disperse in approximately 10,000 years — a relatively short period in astronomical terms.
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:
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.
NASA’s James Webb Space Telescope imaged the planetary nebula NGC 2392, the Lion Nebula, using the observatory’s NIRCam and MIRI instruments. The central star’s remains are responsible for the nebula’s structure, including a lion face-shaped bubble of ionized gas and dust “mane.”
Explore more: Sonification of NGC 2392
View more: Hubble Image of NGC 2392
View more: Chandra X-ray Observatory Image of NGC 2392
More Webb: News | Images | Science | Home Page
Laura Betz
NASA’s Goddard Space Flight Center
Greenbelt, Maryland
laura.e.betz@nasa.gov
Abigail Major
Space Telescope Science Institute
Baltimore, Maryland
Christine Pulliam
Space Telescope Science Institute
Baltimore, Maryland
Scientists from the Max-Planck-Institut für Kernphysik (MPIK) in Heidelberg, Germany, have announced the first successful detection of antineutrinos from an inactive nuclear reactor.
The research team behind the historic achievement said that detecting antineutrinos, which they described as “the most elusive particle in the Universe,” could improve monitoring, maintenance, safety, and security of nuclear reactors.
In a statement announcing the detection, the researchers point out that even when nuclear fission reactors are turned off, “the story inside the reactor core still has a great deal to tell.”
For example, the long-lived fission products inside nuclear reactors continue to decay for months, or in some cases, years after a reactor is no longer in use. This ongoing radioactive decay can produce what the team termed a “faint flux” of the most elusive particle in the universe: antineutrinos.
Because antineutrinos interact only extremely weakly with matter, they pass almost unhindered through the reactor vessel and surrounding shielding. In theory, the right equipment could detect this activity, offering insights into the reactor’s radioactive inner core.
Fortunately, for MPIK study leader Anthony Onillon and co-leader Thierry Lassere from the independent research group OMINA, also located at MPIK, there is an underground detector around 400 meters from two reactor cores, which were part of the region’s Chooz reactor in northern France.
Dubbed ‘Double Chooz,’ the detector contains over 30 cubic meters of liquid “scintillator.” According to the study authors, when antineutrinos interact with this material, a detectable flash of light is emitted.
“Antineutrinos interact only extremely rarely with matter,” Lasserre explained. “However, when one interacts within the Double-Chooz detector, a characteristic double-light signal is produced that can be distinguished from background events.”
To search for the weak antineutrino signal from the decaying Chooz nuclear reactor material, the research team evaluated recorded data from a 17.2-day period when both reactors were shut down. Because antineutrinos interact so rarely with matter, the researchers searched for the characteristic paired flashes produced when one underwent inverse beta decay inside the detector.
After scanning through the data, the team said they found evidence for roughly 100 “antineutrino candidate events” originating from within the reactors. This included signals from the cores and nearby spent-fuel cooling pools.
The researchers said the measured signal “agrees remarkably well” with simulations of the remaining fuel inventory and the decay of long-lived fission products.The team said this detection marks the first direct experimental validation of the antineutrino emissions predicted by the shutdown reactor models.
“With this new work, the experiment has achieved another first: observing the faint neutrino glow that remains after a reactor goes dark,” the research team explained.
When discussing the significance of the achievement, Dr. Onillon noted that previous efforts have primarily focused on operational nuclear reactors, where the antineutrino flux is much larger. Conversely, their detection was made under challenging conditions using methods perfected by the team.
“Detecting the tiny residual signal after shutdown required exceptionally low backgrounds and careful analysis techniques developed by the Double Chooz collaboration over many years,” the researcher explained.
When discussing the experiment’s practical applications, the team noted that the work provides researchers and regulators with “the first published benchmark” of the antineutrino glow coming from shutdown reactors and spent fuel pools. In theory, such detection could provide information on a reactor during both operational and maintenance phases.
“The results demonstrate that antineutrino detectors can probe nuclear reactors even during shutdown periods, opening new perspectives for reactor monitoring, nuclear safety, and safeguards,” they conclude, adding that such detections “may become relevant for independent verification of reactor status and spent-fuel inventories.”
The study “First measurement of neutrino emissions from spent nuclear fuel by the Double Chooz experiment” was published in Physical Review Letters.
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 German eROSITA Consortium (eROSITA-DE), led by the Max Planck Institute for Extraterrestrial Physics (MPE), has completed the most comprehensive census of the high-energy universe ever assembled.
Released as eROSITA Data Release 2 (DR2), the new high-energy universe catalog includes nearly two million X-ray sources, essentially doubling the number cataloged in DR1. The team behind the achievement said the new catalog, which has been made available to the wider scientific community, marks a “major step forward” in mapping the entire high-energy universe.
“DR2 is the best inventory of the X-ray sky we have to date and opens the door to robust statistical studies of cosmic populations,” explained Miriam E. Ramos-Ceja, Ground Segment Manager of the eROSITA instrument and lead author of the DR2 publication.
DR2 was built from the first three scans captured by the eROSITA telescope during the Spectrum-Roentgen-Gamma (SRG) mission. According to a statement emailed to The Debrief, the new high-energy map combined data from multiple passes over the sky, significantly increasing the instrument’s survey depth.
After beginning its mission in December 2019, the observatory surveyed the entire sky every six months. This mission length increased the scans’ depth and sensitivity. The new DR2 includes data captured during the mission’s first 556 days. MPE scientists said the final catalog comprises three “full sky surveys.”
“By stacking these observations, the survey reaches significantly fainter fluxes than the first release, enabling the large increase in detected sources,” they explained.
The approach also revealed a large population of previously uncatalogued systems.
For example, the DR2 catalog includes nearly two million X-ray sources detected in the 0.2–2.3 keV band. The survey also revealed over 1.9 million “point-like sources.” The team said these detections are “primarily stars and actively accreting supermassive black holes.” The survey also added around 64,000 extended sources, including newly cataloged galaxy clusters, nearby galaxies, and supernova remnants.
Along with the primary catalog, the new release includes a complementary “hard-band” catalog that includes 15,000 sources detected at higher energies (2.3–5.0 keV). The team said these detections revealed “heavily obscured and intrinsically energetic systems” that scans performed at ‘softer’ X-ray energies typically overlook.
“Together, these catalogues capture the full diversity of the X-ray sky, from nearby stellar coronae to distant supermassive black holes and massive galaxy clusters,” the team explained, adding that many of the cataloged objects are newly identified in X-rays, while others “can now be studied with substantially improved precision.”
Although more analysis is needed to accurately characterize every high-energy source discovered by the new survey, the team said the DR2 includes “multi-wavelength information” that associates the newly cataloged X-ray detections with their most likely optical and infrared counterparts.
“X-ray detection is only the first step,” explains Mara Salvato, eROSITA spokesperson and chair of the follow-up working group. “By linking X-ray sources to their counterparts at other wavelengths, we can work out what these objects are, where they sit on the cosmic distance ladder, and build clean, well-defined samples on an unprecedented scale.”
This data suggests that approximately 88% of the newly discovered sources come from outside the Milky Way Galaxy. The team said the new sources are “dominated by accreting supermassive black holes.”
When discussing the significance of the new DR2 high-energy catalog, the team highlighted its coincidental release with the latest Sloan Digital Sky Survey (SDSS).
“By combining SDSS spectroscopy with eROSITA’s X-ray data, researchers can build three-dimensional maps of active black holes across the sky, revealing how these rapidly growing objects are distributed and evolve across cosmic time,” they explained.
For example, combining eROSITA’s X-ray catalog with the SDSS spectroscopic and photometric redshift data has already resulted in what the team described as “one of the largest and most detailed studies of accreting supermassive black holes to date.” The researchers said these “elusive objects” formed surprisingly early in the history of the Universe, so capturing new data of their growth at high redshift is invaluable.
“The most luminous black holes at high redshift are like needles in a haystack,” explained the corresponding study’s lead author, William Roster. “Thanks to DR2 we found more needles than expected, suggesting that rapidly growing black holes were more abundant in the early Universe than previously thought”
Due to a pre-existing agreement between the German and Russian eROSITA consortia, the new DR2 covers the western Galactic hemisphere. However, the researchers note, within this region of the sky, the new catalog “represents the largest and most homogeneous public X-ray dataset currently available.”
eROSITA Principal Investigator Andrea Merloni said the new dataset of unprecedented scale and completeness has been made available to the global astronomical community. MPE Director Kirpal Nandra agreed, adding that the MPE team hopes the most complete catalog of high-energy sources ever assembled will provide “a unique foundation for discoveries ranging from rare objects to large-scale population studies.”
“eROSITA just set another world record in terms of X-ray source numbers – and it won’t be the last,” Merloni concluded.
The eROSITA-DE DR2 catalogs, upper-flux-limit server, and full documentation are publicly accessible via the eROSITA-DE Science Data Archive.
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
Teams at Katalyst Space are making progress slowing the spin of their LINK spacecraft, which is designed to boost the orbit of NASA’s Neil Gehrels Swift Observatory. A series of thruster burns this week reduced the rate of spin from approximately 9 degrees per second to less than 4 degrees per second. Katalyst is continuing with this approach to restabilize the spacecraft in the coming days.
Teams also further evaluated LINK’s functionality and determined there are still potential paths forward for a boost. NASA is working closely with Katalyst to consider revised, innovative approaches. The agency will continue to provide updates about stabilization of LINK and next steps for the mission. LINK is now expected to approach Swift around the end of August.
Learn more from Katalyst, and monitor NASA’s Swift blog for continued updates:
https://science.nasa.gov/blogs/swift
The post Efforts Continue to Stabilize LINK Spacecraft for NASA’s Swift Boost appeared first on NASA Science.
Scientists from the Paul Scherrer Institute (PSI), conducting a new series of experiments with millions of ultracold neutrons, have determined that the neutral particles do not switch between our universe and a theoretical “mirror universe” containing oppositely charged, identical counterparts of all elementary particles previously proposed by theoretical physicists.
Although the new experiments do not completely disprove the concept of a mirror universe, the experiments do cast doubt on one of the idea’s fundamental principles, making its existence less likely. The team behind the new study said their findings also aid future experiments by eliminating one potential area of inquiry.
Although theoretical physicists sometimes propose radical concepts, one such idea proposes a mirror universe where every elemental particle has a “twin.” For example, the authors of the new study explain, there would be mirror protons, mirror electrons, and mirror neutrons. Still, they note, interaction between the particles in our universe and their mirror universe companions is likely to be minimal.
Geza Zsigmond, a researcher at the PSI Center for Neutron and Muon Sciences, said the theory suggests that the two mirror particles “sense each other’s presence” through gravity. Some physicists have even suggested that gravitational interaction with mirror-universe particles could explain dark matter. Unfortunately, experiments designed to hunt for the mirror universe have returned zero positive results.
Bernhard Lauss, leader of the research group for ultracold neutron physics at the PSI Center for Neutron and Muon Sciences, said, “There is no way of proving the existence of mirror particles using gravitational interaction alone.” Fortunately, the theory also offers a second testing possibility.
According to Zsigmond and colleagues, mirror universe particles would interact with our universe either through gravitation or through what they described as a “rare” oscillation of neutrons. This means that neutral particles like a neutron could occasionally disappear from our universe and reappear in the mirror universe. Even more surprisingly, the same theory says that these particles could magically return to our universe as well.
“Based on this hypothesis, neutral particles might oscillate to and fro between our normal matter world and the mirror world,” Lauss said.
The team said that this possibility, combined with new experiments at the Institut Laue-Langevin in France that “rekindled” speculation about the mirror universe, focused their new efforts on this “other” property of mirror universe particles.
After joining up with researchers from ETH Zurich and the Jagiellonian University in Kraków, the PSI team designed a series of experiments that should show if neutrons are zipping back and forth between universes. Zsigmond said that neutrons are ideal to test the concept for two reasons. First, they are neutral particles, and second, the researcher said they have a “strange property” the team hoped to exploit.
“Neutrons appear to have different lifetimes, depending on how this is measured,” Zsigmond explained.
Although several theories have been proposed to explain this discrepancy, the team acknowledged that the varying neutron lifetimes could be caused by some of these neutral particles disappearing from our universe and entering the mirror universe.
First, the team used the high-intensity proton accelerator at PSI to generate the millions of neutrons needed for their experiments. Next, the team slowed the neutrons down, creating what scientists call “ultracold” neutrons.
Next, the researchers trapped the ultracold neutrons in a specially designed non-magnetic stainless steel vacuum chamber. Because the theory suggests that the probability of neutrons jumping between universes is extremely sensitive to magnetic fields, the vacuum chamber was surrounded by magnetic field coils that the researchers could control with the required precision.
Throughout the experimentation phase, the researchers stored 1.5 million ultracold neutrons in the chamber every five minutes. After about 200 seconds, the team would empty the chamber and count how many neutrons remained. The team repeated this process over several months, resulting in the creation, storage, and measurement of approximately 25 billion neutrons.
Lauss said the researchers gradually varied the strength and direction of the magnetic field throughout the process to “scan all the relevant regions in which one might expect oscillations between neutrons and mirror neutrons to occur.” However, Lauss said, “we saw no evidence at all of such oscillations.”
When discussing the significance of their findings, the PSI-led team said the lack of evidence of mirror universe oscillation by ultracold neutrons suggests a very high probability that such mirror universe neutral particle roundtrips “can be ruled out.” They also note that failing to find evidence of a mirror universe still resulted in benefits for particle physics by eliminating an area of inquiry.
“By restricting the scope for certain speculations, we are showing researchers in theoretical physics that they need to explore new avenues,” Zsigmond explained. “Physics needs that kind of impetus if it is to continue to evolve.”
Moving forward, the team said that “substantial improvements” to their experiments would require a much more elaborate setup. Until then, they said their experiment and its results are “the best of its kind in the world and will set the standard for the foreseeable future.”
The study “New High-Sensitivity Search for Neutron to Mirror-Neutron Oscillations at the PSI Ultracold Neutron Source” was published in Physical Review Letters.
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
An unusual clump of gas 450 million years after the Big Bang may contain stars hailing from the universe’s elusive first generation of stars. New research examines an alternative explanation involving an accreting black hole.
Hebe is visible in the image on the left as a prominent blob of helium emission up and to the left from GN-z11, a luminous galaxy hosting an accreting supermassive black hole. On the right is an infrared image of the same region, in which Hebe is not visible. Click to enlarge. [Adapted from NASA, ESA, CSA, Ralf Crawford (STScI)]
Before the community settles on this exciting explanation, however, the hypothesis must withstand all the tests astronomers can throw at it. In a recent research article, Junehyoung Jeon, Tae Bong Jeong, and Saiyang Zhang (The University of Texas at Austin) along with Volker Bromm (The University of Texas at Austin) attempted to explain Hebe’s properties in another way.
Hebe glows with distinctive helium emission that requires a source of high-energy radiation. This radiation could be provided by a cluster of Pop III stars, but it could also, in theory, arise from an accreting supermassive black hole embedded within the gas clump.
Predicted total mass of Hebe’s Pop III stars as a function of the Lyman–Werner flux from the nearby galaxy GN-z11. Click to enlarge. [Jeon et al. 2026]
While the black hole scenario could, with reasonable black hole masses, gas densities, and accretion rates, reproduce individual flux measurements drawn from JWST observations, this hypothesis struggled to simultaneously match multiple measurements. The Pop III star cluster scenario, with a cluster mass of a few hundred thousand solar masses, provided the best fit to the JWST data.
Modeled spectral energy distributions (lines) and predicted line flux densities (open symbols) for the accreting black hole, Pop III star, and Pop II (second-generation) star hypotheses. The observed JWST line fluxes are shown as filled circles. Click to enlarge. [Jeon et al. 2026]
While a cluster of Pop III stars is still the leading explanation for Hebe’s properties, the team noted that the Pop III star and black hole hypotheses aren’t mutually exclusive; Hebe could very well harbor a primordial black hole and a smattering of Pop III stars. Regardless of what powers its characteristic helium emission, Hebe offers an enticing glimpse into the early universe, and more work is needed to understand this intriguing object.
“What Is Powering the Enigmatic He II Emitter Hebe: The First Stars or Black Holes?” Junehyoung Jeon et al 2026 ApJ 1006 27. doi:10.3847/1538-4357/ae7bea
The post First-Generation Stars Provide Better Fit than a Black Hole for Early-Universe Gas Clump appeared first on AAS Nova.
NASA’s Neil Gehrels Swift Observatory captured an “orphan” black hole lighting up as it devoured a star on the outskirts of a faraway galaxy. These phenomena are rare to begin with, and none had ever before been seen so far outside of a galaxy’s core.
“We were looking for these star-shredding events as a way to find otherwise invisible supermassive black holes wandering away from the galactic cores where they usually reside,” said Robert Stein, a research fellow at The University of Maryland, College Park and NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “With this discovery, which is one of just a couple that have been confirmed so far, we’ve validated a new technique and can use it to hunt for more.”
A paper describing the results, led by Stein, was published Monday in The Astrophysical Journal Letters.
Researchers saw an ultrabright flare unleashed by a star being torn apart by extreme gravitational forces after drifting too close to a monster black hole — a phenomenon called a tidal disruption event. The black hole behind the blast weighs in at about a million times the Sun’s mass. Its existence was first flagged in November 2025 as an unusual brightening in a galaxy about 750 million light-years away by ZTF (Zwicky Transient Facility), a survey conducted by the Palomar Observatory in Southern California.
“Out of the half million flashes ZTF detects each night, our new artificial intelligence algorithm automatically recognized a flare that looked a lot like a tidal disruption event, despite its unusual location in the outskirts of a galaxy,” Stein said. For a few months, the tidal disruption event outshone its entire host galaxy in ultraviolet wavelengths, temporarily radiating with the light of about 10 billion suns.
Other telescopes, including the SOAR (Southern Astrophysical Research) telescope in Chile, followed up on the ZTF source to look at the event’s spectrum, which revealed features supporting that it was likely a tidal disruption event. Astronomers then used NASA’s Swift to look at wavelengths they can’t detect with ground-based telescopes to uncover new information. For example, Swift’s UVOT (Ultraviolet/Optical Telescope) took the blip’s temperature and found that it had quite a fever at about 54,000 degrees Fahrenheit (30,000 degrees Celsius).
“The combination of all this data helped us rule out other explanations and confidently say it’s a tidal disruption event, despite its strange location,” said Jonathan Carney, a doctoral student at the University of North Carolina at Chapel Hill, who took the first spectra that supported the flare’s interpretation as a tidal disruption event.
Nearly every galaxy in the universe is anchored by a supermassive black hole sitting right in the center. About once every 100,000 years, a star will drift too close to this invisible heavyweight and trigger a tidal disruption event.
While they’re rather rare in any given galaxy, scientists scour millions of galaxies for them. Each year, astronomical surveys typically spot about 30 tidal disruption events occurring somewhere in the universe.
Prior to 2024, they’d only been seen in galaxy cores. That’s partly because astronomers mainly looked for them there; after all, it’s where all the known supermassive black holes were, and you can’t get a tidal disruption event without one (the gravitational pull of lighter black holes isn’t strong enough).
Then scientists saw the telltale signs of a star being shredded 2,600 light-years from the center of its host galaxy. That inspired more astronomers to look beyond galaxy cores for similar events, and now a team has identified one more than 30,000 light-years away from a galaxy’s center.
So how did the newfound black hole become so off-kilter?
“It must have originated in a galaxy’s center, but not the one it’s in the outskirts of now,” Stein said. “We think the host galaxy’s supermassive black hole is still at its core, but the one eating the star could have started off in a small galaxy that merged with the big one we see today.”
The researchers have outlined two possibilities. Three or more galaxies may have merged together, and the gravitational tug-of-war between their central supermassive black holes may have flung the lightest black hole out to the galaxy’s edge.
Or a dwarf galaxy could be midway through a merger. As the dwarf’s stars fell into the larger galaxy, one may have passed too close to the dwarf’s supermassive black hole.
“Further discoveries could reveal the origin of this apparent ‘orphan’ black hole,” Stein said. “The key science question we want to answer is: How common are wandering black holes?”
The answer may soon be within reach. “Pointed science observations with Swift’s UVOT and XRT (X-Ray Telescope) instruments are temporarily suspended as the mission awaits an orbit boost, which is planned for this summer,” said co-author S. Bradley Cenko, Swift’s principal investigator at NASA Goddard. The spacecraft, whose primary mission ran from 2004 to 2006, is slowly sinking toward Earth due to atmospheric drag after more than 20 years of observations of the changing universe. Nudging it to a higher orbit could extend its lifetime even longer. “Once it resumes normal operations, Swift could continue searching for more examples of out-of-place black holes.”
In the coming years, scientists will use the new technique to search for disintegrating stars in observations from the newly operational Vera C. Rubin Observatory, jointly funded by the U.S. Department of Energy and National Science Foundation, in Chile and NASA’s upcoming Nancy Grace Roman Space Telescope.
“Rubin’s wide, deep surveys will reveal a much larger sample of tidal disruption events than current observatories are capable of collecting, including ones that are off-center,” Carney said. “And Roman’s space-based surveys will extend the current search zone by seeing ones that are farther away, looking back through 9 billion years of cosmic history.” Adding their observations to Swift’s and those from ground-based observatories will bring astronomers closer than ever before to completing a census of the universe’s behemoth black holes.
To learn more about the Swift mission, visit:
By Ashley Balzer
NASA’s Goddard Space Flight Center, Greenbelt, Md.
Media contact:
Claire Andreoli
NASA’s Goddard Space Flight Center, Greenbelt, Md.
301-286-1940
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