The target is the hydrogen 21-centimetre line, a natural radio signal produced by the spin state of neutral hydrogen atoms. In the early universe, hydrogen was the dominant element, and its atoms interacted with the surrounding radiation and matter in ways that encoded information about temperature, density and the influence of gravity. The signal is expected to contain clues about the conditions between the end of the Big Bang’s afterglow and the formation of the first stars, a period often described as the cosmic dark ages. Because the first stars had not yet begun producing light, hydrogen is one of the only available messengers from this otherwise invisible chapter of cosmic history.

Observing the signal from Earth is exceptionally difficult. As the universe expanded, the original 21-centimetre emission was stretched to much longer wavelengths, shifting it into a frequency range of approximately 10 to 50 megahertz. These frequencies are strongly affected by Earth’s ionosphere, which can absorb, distort or reflect incoming radio waves. Even when a signal reaches the ground, it is buried beneath powerful interference generated by radio stations, satellites, mobile communications and other human technologies. The Milky Way also produces intense radio emission, creating a foreground that can be millions of times brighter than the cosmological signal scientists are trying to isolate.

CosmoCube’s solution is to use the Moon as a natural radio shield. In lunar orbit, the spacecraft will spend roughly 40 minutes of every two-hour orbit above the far side, where the bulk of the Moon blocks radio noise from Earth. This temporary radio silence will not make the universe quiet, but it will remove one of the largest sources of contamination facing low-frequency astronomy. During an expected two-year mission, the satellite could collect approximately 1,000 hours of observations while shielded from terrestrial interference. By combining measurements gathered across many orbits, researchers hope to build a statistically reliable picture of the early hydrogen signal.

The spacecraft will carry a miniature, fully integrated radiometer, an instrument designed to measure extremely weak variations in radio brightness. Its antenna will unfold in lunar orbit and scan the sky for the broad spectral signature of neutral hydrogen. Rather than producing a conventional image of individual stars or galaxies, CosmoCube will measure how the average radio signal changes with frequency and direction. Those changes could reveal the thermal history of the early universe and indicate when the first sources of light began altering the surrounding hydrogen. Because the mission is expected to operate at frequencies inaccessible to most ground-based observatories, it will explore a region of cosmic history that remains largely beyond the reach of existing facilities.

Extreme sensitivity creates its own technical problems. Tiny changes in the spacecraft’s electronics, temperature or antenna response can imitate the gradual signal variations expected from the early universe. To combat this, CosmoCube will use a Dicke-switched calibration system that repeatedly compares the sky with several built-in reference sources. This process allows the instrument to track and correct internal gain changes and electronic noise. The calibration strategy is essential because the spacecraft is not simply searching for a bright, isolated transmission; it is attempting to identify a minute cosmological imprint hidden inside the instrument’s own response and the much stronger radiation of the Galaxy.

After the data return to Earth, the team will apply Bayesian statistical methods to separate the likely cosmological signal from foreground emission. Bayesian analysis allows researchers to combine measurements with physical models and calculate which possible signal histories best fit the observations. Computer simulations and in-flight measurements will also be used to reconstruct the antenna’s response to different parts of the sky. This response, known as the beam pattern, determines how much radiation from each direction contributes to a measurement. Correcting for it will help the scientists subtract distortions and distinguish genuine features of the 21-centimetre signal from artefacts introduced by the spacecraft or observing geometry.

The scientific payoff could extend beyond the history of the first stars. CosmoCube may also test how dark matter shaped the early universe. Although dark matter does not emit or absorb light in the ordinary way, its gravity helped pull hydrogen into denser regions, eventually creating the seeds of the first stars and galaxies. Different dark-matter properties would leave different signatures in the distribution and temperature of early hydrogen. By comparing the observed radio spectrum with theoretical models, scientists could investigate how rapidly matter clumped together and how the unseen component of the universe influenced the transition from darkness to Cosmic Dawn. Such measurements could complement observations from larger telescopes that study later stages of cosmic evolution.

The mission has received support from the UK Space Agency, the Kavli Foundation and the Science and Technology Facilities Council, part of UK Research and Innovation. Surrey Space Technology Limited is developing the spacecraft platform, known as SSTL-21, while researchers at the University of Cambridge, the University of Portsmouth and STFC RAL Space are contributing to the science and engineering. Partners from European countries, including Malta, are also involved. Working laboratory prototypes have already been built, and representative spacecraft and payload models are undergoing environmental testing to assess whether the instrument can maintain the required thermal and electronic stability in lunar orbit. The team has participated in the European Space Agency’s mini-Fast mission call, with a proposed mission cost below €50 million, and hopes CosmoCube could launch within the next five years.

CosmoCube will not be the only project seeking shelter behind the Moon. Space agencies in the United States, India and other countries are developing concepts for lunar-orbiting or lunar-surface radio observatories, recognizing that the far side offers a rare zone protected from Earth’s technological noise. What makes the British proposal especially notable is its compact scale: a relatively small spacecraft is being designed to perform precision cosmology in one of the most demanding environments accessible to modern space science. If its calibration systems and analysis techniques work as planned, CosmoCube could turn the Moon into a listening post for the universe’s earliest audible trace, bringing scientists closer to understanding how the first stars emerged from the darkness.

Subject of Research:
The cosmic dark ages, the 21-centimetre hydrogen signal, Cosmic Dawn and the influence of dark matter on the formation of the first stars and galaxies.

Article Title:
The CosmoCube Lunar Mission for Probing the Dark Ages and Cosmic Dawn via 21-cm Cosmology

News Publication Date:
14-Aug-2026

Web References:
https://www.nature.com/articles/s41550-026-02946-y

References:
Nature Astronomy, DOI: 10.1038/s41550-026-02946-y

Image Credits:
Surrey Space Technology Ltd

Keywords

CosmoCube, lunar mission, cosmic dark ages, Cosmic Dawn, 21-centimetre cosmology, neutral hydrogen, dark matter, radio astronomy, Moon, University of Cambridge, low-frequency astronomy, early universe

The finding comes from a laboratory study in which researchers examined how participants with varied levels of technical experience responded to an attacker-controlled passkey. The team wanted to understand whether ordinary users could recognize that an unauthorized authentication method had been added to their account and whether they could successfully regain control. The results, according to the researchers, “paint a grim picture” of users’ ability to identify and resolve this type of compromise without outside help.

Passkeys are based on public-key cryptography rather than a shared secret. When a user creates one, a private cryptographic key is stored on a device or within an approved password manager, while the associated public key is registered with an online service. During login, the device proves possession of the private key without transmitting it to the website. The process is typically unlocked through a fingerprint, facial recognition, device PIN or another local method, meaning that a website does not receive or store a conventional password that could later be stolen.

That design can provide strong protection against common attacks, but it does not eliminate the danger posed by someone who already has access to a trusted device or account credentials. An abusive partner who can unlock a computer, learn the account password or otherwise enter an account may be able to create a new passkey under their own control. Once registered, the passkey can allow the attacker to authenticate again in the future, potentially without knowing the victim’s current password. The technical strength of the passkey itself does not reveal who originally added it or whether the person using it is acting with the account holder’s consent.

The Cornell researchers tested this problem through account security interfaces, or ASIs—the screens and controls that allow users to inspect login activity, manage authentication methods and recover compromised accounts. Participants interacted with passkey systems offered by three different services. Most could not determine which login originated from the attacker’s device. Many also struggled to remove the unauthorized passkey, change the account password and sign out other active devices as a coordinated response to the intrusion.

The study also exposed the limits of security notifications as a defense. Some participants noticed or questioned emails warning them about unusual account activity, but others regarded the messages with suspicion or did not understand what the notifications were communicating. Online security alerts often compress complex technical events into brief explanations, leaving users to interpret unfamiliar terms such as passkey, device session, authentication method or security key. In an abusive relationship, where an attacker may monitor communications or react quickly to account changes, confusion can carry consequences beyond ordinary inconvenience.

The passkey management interfaces themselves were difficult for participants to follow across all three services examined. Users were not always sure how many passkeys existed, which devices they belonged to or whether deleting one would actually block the attacker. The researchers argue that an account owner should be able to answer basic questions immediately: Which authentication methods are active? When and where were they created? What devices can still access the account? Which action will remove an intruder completely? In the tested systems, those answers were not consistently clear.

“Our conclusion is that services need to do a lot of work to enable users to diagnose compromises to their account, and remediate any account compromise that could occur,” said Alaa Daffalla, a doctoral student in computer science at Cornell and lead author of the study, titled “‘Maybe There’s Only One Passkey?’: Challenges Investigating and Remediating Adversarial Passkeys.” The research is being presented at the 35th USENIX Security Symposium in Baltimore. Daffalla joined the laboratory in 2022 and has focused on the design and usability of account security interfaces.

The work grew out of Cornell’s Clinic to End Tech Abuse, or CETA, which was co-founded in 2018 by Nicola Dell, an associate professor of information science at Cornell, and Thomas Ristenpart, a professor of computer science at the University of Toronto. CETA supports survivors of intimate partner violence and has helped researchers understand how seemingly helpful technologies can be misused by someone with physical proximity, coercive control or access to a victim’s devices. The new study applies those concerns to an authentication technology increasingly promoted as the future of secure login.

“Understanding the security of online accounts, including emerging authentication mechanisms like passkeys, is essential for digital safety, not only for abuse survivors but for all technology users,” Dell said. The researchers emphasize that the problem is not necessarily that passkeys are cryptographically weak. Instead, the danger arises from the surrounding account-management experience: the ability to add an authentication method, the visibility of existing methods and the tools available when an account has already been compromised. Without effective recovery controls, a system designed to prevent remote credential theft may still provide an attacker with durable access after a brief opportunity to use the victim’s device.

The findings point to a need for services to treat passkey enrollment and removal as high-risk account events. Users may need clearer records showing when each passkey was created, the device or account that controls it and the last time it was used. Recovery workflows should make it possible to revoke suspicious passkeys, invalidate active sessions, change passwords and review other security settings from a single, understandable process. Those measures could benefit anyone whose device or account has been accessed by another person, but they may be particularly important for people facing stalking, surveillance or intimate partner abuse, for whom an invisible authentication method can become a tool of continued intrusion. The research was supported in part by grants from the National Science Foundation and by a Google Cyber Award.

Subject of Research: Passkey security, account compromise and digital safety for people experiencing intimate partner abuse

Article Title: “‘Maybe There’s Only One Passkey?’: Challenges Investigating and Remediating Adversarial Passkeys”

News Publication Date: August 13, 2026

Web References: USENIX Security Symposium study page; Cornell Chronicle story; Clinic to End Tech Abuse

References: National Science Foundation grants; Google Cyber Award

Keywords

Passkeys, cybersecurity, account security, public-key cryptography, intimate partner abuse, digital privacy, authentication, online safety, Cornell University, USENIX Security Symposium

H₃⁺ is a small but extraordinarily important ion in hydrogen-rich atmospheres. It forms when hydrogen molecules are ionized by energetic solar radiation or by particles accelerated within a planet’s magnetic environment. In Jupiter’s auroral regions, intense electron precipitation provides an especially efficient source of ionization. Once produced, H₃⁺ radiates strongly in the infrared, making it a valuable tracer of atmospheric temperature, energy deposition and ionospheric dynamics. Its emissions have long allowed researchers to study Jupiter’s polar atmosphere from afar, but those observations could not directly determine how much H₃⁺ was present at particular altitudes or whether it was moving away from the planet.

The new study changes that picture by detecting H₃⁺ plasma in situ, directly within the auroral region rather than through infrared light integrated along a distant line of sight. That distinction is crucial. Remote observations combine emissions from broad regions of the atmosphere, making it difficult to separate structures at different heights or to follow the motion of individual plasma populations. An in situ measurement can identify the ions themselves and determine how their density and velocity vary within the surrounding space plasma. The result is direct evidence that H₃⁺ exists as a mobile, dynamically important component of Jupiter’s polar environment.

The measurements also revealed intermittent bursts of H₃⁺ flowing upward from the ionosphere. These outflows reached velocities greater than Jupiter’s escape speed, meaning that at least part of the ion population possesses enough kinetic energy to overcome the planet’s powerful gravitational field. Rather than rising briefly and falling back into the atmosphere, these ions can be carried outward into the magnetosphere and, in the fastest events, escape Jupiter altogether. The finding identifies H₃⁺ as a previously overlooked vehicle for removing both mass and energy from the Jovian atmosphere.

The estimated loss rate is on the order of 10²⁶ H₃⁺ ions per second. In planetary terms, that is a substantial flow, even though H₃⁺ represents only a trace component of Jupiter’s overwhelmingly hydrogen-dominated atmosphere. The escape does not imply that Jupiter is rapidly losing its atmosphere or that the planet’s structure is threatened. Jupiter is enormously massive, and its atmospheric reservoir is vast. Instead, the result reveals a persistent form of coupling between the ionosphere and magnetosphere, in which a chemically distinctive ion can transport atmospheric material into the surrounding plasma environment.

The researchers propose that the outflow begins in regions associated with upward electric currents above the auroral ionosphere. Jupiter’s aurora is powered by the interaction between the planet’s rapidly rotating magnetic field, its magnetosphere and charged particles moving along magnetic field lines. In these regions, electromagnetic energy can be transferred into the upper atmosphere through particle precipitation, electric fields and plasma waves. Plasma-wave interactions may first disturb and energize H₃⁺ near the ionosphere. The ions can then be accelerated further by electric potential structures that develop above the atmosphere, producing the observed high-speed outflows.

This mechanism illustrates why H₃⁺ is more than an infrared thermometer. As a molecular ion, it participates in the chemistry and electrical conductivity of the upper atmosphere. The abundance and distribution of H₃⁺ influence how easily electric currents can flow through the ionosphere, while the currents themselves help shape the electric fields that govern charged-particle motion. In this way, H₃⁺ may form part of a feedback system: auroral energy creates the ions, the ions alter ionospheric conductance, and the resulting electrodynamic environment helps regulate their transport into the magnetosphere.

The discovery also helps resolve a long-standing observational problem in planetary science. Jupiter’s auroral emissions are among the brightest and most complex in the Solar System, but infrared brightness alone cannot reveal the complete three-dimensional structure of the plasma above the clouds. A bright signal may represent dense plasma, high temperature, enhanced excitation or a combination of these factors. Direct detection of escaping H₃⁺ provides a physical link between the remote-sensing signatures and the actual movement of atmospheric ions. It gives researchers a way to test models of auroral heating, ionospheric conductivity and atmospheric escape against measurements made in the plasma itself.

Jupiter may not be unique. Other planets and moons with hydrogen-rich atmospheres, strong magnetic fields and infrared aurorae could host related processes. The same general chain—ion production, wave-driven energization, electric acceleration and eventual escape—could operate wherever auroral currents connect an atmosphere to a powerful magnetosphere. The new result therefore extends beyond a single planet. It suggests that molecular ions can serve as active messengers between atmospheric chemistry and space plasma physics, carrying energy and material from a planetary ionosphere into its magnetospheric surroundings. For Jupiter, the aurora is now shown to be not only a spectacular light display, but also an engine of atmospheric escape.

Subject of Research: Direct in situ detection and atmospheric escape of trihydrogen cations (H₃⁺) from Jupiter’s polar auroral regions.

Article Title: Ionospheric escape of H₃⁺ from Jupiter’s polar regions

Article References: Wang, Jz., Bagenal, F., Szalay, J.R. et al. Ionospheric escape of H₃⁺ from Jupiter’s polar regions. Nature Astronomy (2026). https://doi.org/10.1038/s41550-026-02950-2

Image Credits: AI Generated

DOI: https://doi.org/10.1038/s41550-026-02950-2

Keywords: Jupiter, H₃⁺, trihydrogen cations, aurora, atmospheric escape, ionosphere, magnetosphere, plasma physics, planetary science, space weather

MoM-BH*-1 was observed as it existed only a few hundred million years after the Big Bang, when the universe was still in its infancy. At that time, the first stars and galaxies were beginning to assemble from largely pristine clouds of hydrogen and helium. Yet this object was anything but faint or ordinary. It radiated approximately 100 billion times more energy than the Sun, an output far beyond what any conventional star can sustain through nuclear fusion. Its apparent diameter may have been comparable to the scale of our Solar System, making it enormous even by the standards of the most extended stars known today.

The object was found during a JWST survey called Mirage or Miracle, or MoM, which was designed to search for extremely distant galaxies and investigate how rapidly the first luminous structures formed. In deep images, MoM-BH*-1 stood out as an intensely bright, unusually red point of light. Astronomers initially considered the possibility that the red appearance resulted from dust, since interstellar dust absorbs shorter wavelengths of light and allows longer, redder wavelengths to dominate. However, the object’s spectrum contained several features that did not fit a conventional dusty galaxy or star.

One of the most important clues was a remarkably deep Balmer break. This spectral feature occurs when hydrogen gas absorbs photons at specific wavelengths associated with electronic transitions in hydrogen atoms. In ordinary stellar atmospheres, the Balmer break can reveal the temperature and age of a population of stars. In MoM-BH*-1, however, the drop in emitted light was far stronger than expected from normal stars. The pattern suggested that the source was surrounded by an exceptionally dense layer of hydrogen, one so thick that it behaved more like a stellar surface than a diffuse interstellar cloud.

The spectrum also showed almost no evidence of elements heavier than hydrogen and helium. Astronomers refer to these heavier elements collectively as metals, even when discussing elements such as oxygen, carbon or nitrogen. In the modern universe, stars and galaxies generally contain metals created by earlier generations of stars. But the early universe had not yet been enriched extensively by stellar explosions, so a metal-poor environment is plausible at cosmic dawn. The near absence of metals in MoM-BH*-1 nevertheless added to the object’s unusual character and helped constrain the possible explanations.

The researchers used computer simulations to test whether a cloud of nearly pure hydrogen could produce the observed red color and spectral break without relying on dust. Their models showed that it could, but only if the gas were extraordinarily dense and arranged as an extended, opaque envelope around a powerful central source. Such an envelope could obscure the source’s inner radiation at selected wavelengths while allowing other light to escape. The result would resemble a huge star from a distance, even though the energy would not be generated by fusion in a stellar core.

Nuclear fusion cannot plausibly account for MoM-BH*-1’s luminosity. Even the most massive stars eventually reach physical limits imposed by radiation pressure, fuel consumption and the stability of their atmospheres. As a star becomes more luminous, the outward pressure of its radiation can overwhelm gravity and drive away the material needed to sustain it. A black hole, by contrast, can release enormous amounts of energy as gas spirals inward. In an accretion disk, gravitational potential energy is converted into heat and radiation before matter crosses the event horizon. This process can power quasars and active galactic nuclei, some of the brightest phenomena in the universe.

In the researchers’ preferred model, MoM-BH*-1 contains a black hole roughly 100,000 times more massive than the Sun. Around it lies a dense, star-like cocoon of hydrogen approximately the size of the Solar System. As gas falls toward the black hole, it would generate intense radiation, while the surrounding envelope would absorb, scatter and reshape that radiation. The envelope would therefore determine much of the object’s observed appearance, producing the red color and deep Balmer break. The proposed structure is neither a conventional star nor a standard exposed quasar, but a black hole embedded inside a massive, luminous atmosphere.

The discovery may have broad implications for the population of little red dots that JWST has found across the early universe. These compact red sources appear in large numbers in observations of galaxies formed during the first billion years of cosmic history, but they are difficult to classify. Some look too bright to be ordinary stellar systems, while their spectra can differ from those of familiar active galaxies. They also seem to become rare or disappear entirely in the modern universe. The black hole star model suggests that at least some of these objects could be young, short-lived phases in the growth of massive black holes, hidden inside dense clouds of primordial gas.

MoM-BH*-1 is particularly valuable because it appears to outshine any surrounding host galaxy, allowing astronomers to study the proposed black hole-star emission almost in isolation. Other little red dots may contain similar objects, but their light could be mixed with radiation from ordinary stars and gas in their host galaxies. Future JWST observations, especially more detailed spectroscopy, will be crucial for testing whether the source contains the predicted signatures of accretion, dense hydrogen and a powerful central engine. If confirmed, black hole stars could offer a new pathway for producing massive black holes so early in cosmic history—and help explain how the universe created its first quasars only a few hundred million years after the Big Bang.

Subject of Research: A proposed black hole star, MoM-BH*-1, observed in the early universe with NASA’s James Webb Space Telescope.

Article Title: “A Gas Enshrouded and Gas Reddened Black Hole at Cosmic Dawn”

Web References: https://doi.org/10.1038/s41586-026-10846-4

References: Nature, DOI: 10.1038/s41586-026-10846-4

Image Credits: Jose-Luis Olivares, MIT

Keywords

James Webb Space Telescope, black hole star, MoM-BH*-1, little red dots, cosmic dawn, early universe, black hole accretion, primordial hydrogen, Nature, astronomy

The idea challenges the familiar image of a black hole as a cosmic vacuum cleaner. Although a black hole’s gravity can capture matter that crosses its event horizon, the material surrounding a supermassive black hole is not simply swallowed. Instead, gas and dust can form a rapidly rotating accretion disk, with the outer regions extending across vast distances. In these cooler, denser zones, dust grains may collide, stick together and gradually assemble into larger bodies. Lyra and his collaborators argue that this environment could resemble a protoplanetary disk, but on a vastly larger and more energetic scale.

“We’re finding objects that are a thousand times the mass of the Earth, but built of pure dust,” Lyra said. “And not only that, but also some of these objects are approaching the mass of the Sun.” The results come from computational modeling conducted by Lyra, Bhupendra Mishra and collaborators at the American Museum of Natural History and other institutions. Their paper, “Active Galactic Nucleus Tori: Potential Birthplace to Millions of Planets,” published in the Astrophysical Journal, explores how solid material could accumulate inside the toroidal structures surrounding active galactic nuclei, or AGNs.

An AGN is the compact, intensely luminous region at the center of a galaxy where a supermassive black hole is actively consuming matter. As gas spirals inward, friction and compression heat it to extraordinary temperatures, causing it to radiate across the electromagnetic spectrum. The black hole itself remains invisible, but its accretion disk and surrounding clouds can shine brighter than the combined light of billions of stars. According to the simulations, the outer regions of this system may be sufficiently cool for dust to survive while still containing enough material and orbital structure for solid bodies to grow.

The proposed mechanism begins with small dust particles embedded in the AGN’s rotating disk. Collisions can cause these grains to clump, creating larger aggregates that interact gravitationally with the surrounding gas and with one another. Over millions of years, the bodies could migrate through the disk, alter their orbits and collide. This process resembles the growth of planetary embryos in the disk around a young star, but the scale is dramatically different. Instead of assembling planets from a relatively modest stellar system, the AGN channel could generate enormous populations of massive objects around a central black hole.

The researchers describe this as a bottom-up pathway for creating not only planets but also stars and black holes. Conventional star formation generally proceeds through gravitational collapse: a giant cloud of gas becomes unstable, contracts under its own gravity and eventually forms a star. In the proposed AGN environment, the sequence could run in reverse. Solid bodies would first emerge from dust, then accumulate gas as their gravity increased. If they became sufficiently massive, some could reach the threshold for nuclear fusion and ignite as stars. The most massive stars could then exhaust their fuel and collapse into black holes.

That possibility gives the AGN channel implications far beyond planetary science. The resulting stellar-mass black holes could remain embedded in the accretion disk, migrate toward the galactic center and interact with other black holes. Repeated encounters and mergers might produce black holes hundreds of times more massive than the Sun, potentially helping explain how heavy black holes form in cosmic environments where standard growth mechanisms appear too slow. “They’re hundreds or thousands of times the size of the Sun,” Mishra said, noting that their movement and mergers could generate gravitational waves detectable by future observatories.

One of the most striking predictions is that these hypothetical planets and compact objects could reveal themselves through microlensing. When a massive object passes between an observer and a bright background source, its gravity bends spacetime and magnifies the light behind it. The resulting change in brightness produces a characteristic light curve. Objects orbiting inside an AGN disk could therefore act as gravitational lenses, temporarily brightening the active nucleus in patterns that differ from ordinary variability. Detecting these predicted signatures would provide a direct test of whether planet formation is taking place around supermassive black holes.

The researchers also anticipate that gravitational-wave observations could offer an independent test. As black holes migrate inward and merge, they should send ripples through spacetime. The Laser Interferometer Space Antenna, or LISA, a planned European Space Agency mission involving three spacecraft linked by laser beams, is being designed to detect low-frequency gravitational waves from massive black-hole systems. Before such observations become possible, the team intends to build more sophisticated simulations incorporating magnetic fields, turbulence, gas inflow and the complex geometry of the accretion disk. These models could predict electromagnetic signals accompanying gravitational-wave events and clarify whether the apparent cosmic nursery around a black hole can truly give birth to worlds, stars and new generations of black holes.

Subject of Research:
Computational modeling of planet, star and black-hole formation in active galactic nucleus tori surrounding supermassive black holes

Article Title:
Active Galactic Nucleus Tori: Potential Birthplace to Millions of Planets

Web References:
https://iopscience.iop.org/article/10.3847/1538-4357/ae6f0b

References:
Lyra, W., Mishra, B., McKernan, B., Mac Low, M.-M., Ford, S., Cook, H. E. “Active Galactic Nucleus Tori: Potential Birthplace to Millions of Planets.” The Astrophysical Journal.

Image Credits:
NMSU Photo by Josh Bachman

Keywords

supermassive black holes, active galactic nuclei, planet formation, exoplanets, accretion disks, cosmic dust, gravitational waves, microlensing, LISA, computational astrophysics

The discovery, reported in Nature by researchers from the Institute of Science and Technology Austria and international collaborators, emerged from the JWST “Mirage or Miracle” survey. The program was designed to investigate distant sources whose appearances could be deceptive: some might be extraordinary galaxies from the early Universe, while others could be nearby objects masquerading as remote cosmic systems. The survey has already produced major discoveries, including the extremely distant galaxy MoM-z14. In the case of MoM-BH*-1, the light detected by JWST began its journey roughly 13 billion years ago. Because the expansion of the Universe stretches light toward longer, redder wavelengths, the object now appears as a faint, highly redshifted source whose spectrum preserves information about the physical conditions surrounding its central black hole.

Unlike the familiar image of a black hole surrounded by a thin, pancake-shaped accretion disk, a black hole star would be concealed within a much larger cloud of gas. Matter falling inward would release enormous amounts of energy, but the surrounding gas would absorb, scatter, and reprocess that radiation before allowing it to escape. The result would be an object whose outward appearance is dominated not by the black hole itself, but by a glowing, turbulent envelope. The proposed black hole stars could reach sizes of approximately 1,000 astronomical units, more than 100,000 times the diameter of the Sun and comparable in scale to the broad regions associated with powerful accretion systems. Their envelopes would remain gravitationally connected to the central black hole while radiating in a way that could imitate the light of a stellar population or a compact galaxy.

MoM-BH-1 is particularly important because its spectrum contains both black-hole-like and star-like signatures. One of the strongest clues is a feature known as the Balmer break, a sharp change in the amount of light emitted across a region of the spectrum associated with hydrogen absorption. In ordinary galaxies, the strength of this feature can reveal the ages and compositions of stars. In MoM-BH-1, however, the Balmer break is unusually pronounced—stronger than those typically observed in star-forming galaxies, dust-free stellar populations, or the enigmatic objects JWST researchers call “little red dots.” The combination suggests that the source is not simply a conventional galaxy filled with young stars. Instead, the spectral shape may be produced when radiation from a growing black hole passes through an exceptionally dense, dust-free gas envelope.

This distinction could help solve a central problem in the study of little red dots. Since their discovery in JWST observations, these compact, intensely red sources have generated competing explanations. Some researchers have argued that they are heavily obscured active galactic nuclei, while others have suggested that their light may come from unusual stellar populations or compact galaxies. A major difficulty has been separating the radiation from a possible central black hole from the light of its host galaxy. MoM-BH*-1 appears to offer a cleaner laboratory because nearly all of the detected emission can be attributed to the central object, with little evidence for a substantial host galaxy contributing to the observed brightness. Its red appearance may therefore be caused not primarily by dust blocking the light, but by gas scattering the radiation and shifting its emergent spectrum toward redder wavelengths, in a process loosely comparable to the way Earth’s atmosphere reddens a sunset.

The researchers modeled MoM-BH*-1 as a small, rapidly growing supermassive black hole embedded in extremely dense and turbulent gas. Under normal circumstances, the energy released by accretion can limit how quickly a black hole grows. As radiation pressure increases, it can push back against the inflowing material, creating a theoretical ceiling known as the Eddington limit. But dense environments may permit “super-Eddington” accretion, in which matter falls inward faster than conventional models allow. If the inflowing gas is sufficiently thick and dynamically complex, radiation can become trapped and carried inward with the material rather than immediately escaping. This would enable the black hole to gain mass at an accelerated rate, potentially allowing a relatively small initial seed to become enormous within a few hundred million years.

That possibility is significant because some quasars observed in the early Universe appear to contain black holes with masses of hundreds of millions or billions of Suns at a time when there should not have been enough time for ordinary growth processes to produce them. Astronomers have proposed several solutions, including the formation of unusually massive “direct-collapse” black-hole seeds, rapid mergers, and episodes of super-Eddington accretion. Black hole stars could provide an observable signature of the latter process. Rather than being a final state, the objects may represent a short-lived phase in which a black hole is growing inside a massive gas reservoir. As the envelope changes, collapses, or is expelled, the system could evolve into a more familiar active galactic nucleus and eventually become the central engine of a luminous quasar.

The connection to little red dots becomes even stronger when the researchers consider MoM-BH*-1’s surroundings. The object lies near a brighter galaxy, and models indicate that the two systems could merge in roughly 100 million years. When the spectra of the black hole star and its neighboring galaxy are combined, the result closely resembles the characteristic appearance of little red dots. This suggests that some of the mysterious JWST sources may not be a single type of object, but systems in which a black hole star is embedded within, or interacting with, a young host galaxy. In that scenario, the compact black hole star would supply the intense central radiation, while the surrounding galaxy would modify the total spectrum seen by distant observers. The result could look like a red, compact, rapidly evolving “baby quasar.”

The discovery is also part of a broader pattern. In March 2025, researchers announced another candidate black hole star, nicknamed “The Cliff,” associated with the period known as cosmic noon, roughly two to three billion years after the Big Bang. That era marked the height of star formation and galaxy growth. A further object identified near cosmic noon was described in a recent Astrophysical Journal Letters study by researchers including ISTA postdoctoral scientist Alberto Torralba and Jorryt Matthee. Finding similar sources at different cosmic epochs suggests that black hole stars may not be restricted to the earliest Universe, although they could have been more common when gas supplies were richer and galaxies were undergoing rapid assembly. Closer examples also offer astronomers an opportunity to obtain higher-quality spectra with ground-based observatories such as the European Southern Observatory’s Very Large Telescope.

The team emphasizes that black hole stars remain a developing interpretation rather than a fully established population, and future JWST observations will be essential for testing the idea. Astronomers will search for additional sources with the same combination of strong Balmer breaks, red continua, and signatures of dense gas surrounding an accreting black hole. Measurements of emission lines, variability, spatial structure, and the relationship between these objects and nearby galaxies could determine whether black hole stars are common precursors to quasars or a rarer phenomenon. If confirmed, they would reshape models of black-hole growth by showing that the earliest black holes could temporarily hide inside star-like cocoons while consuming gas at extreme rates. MoM-BH*-1 therefore offers more than a striking new name: it may be a direct glimpse of the growth phase that allowed the Universe’s first supermassive black holes to become cosmic giants so quickly.

Subject of Research: Not applicable

Article Title: A Gas Enshrouded and Gas Reddened Black Hole at Cosmic Dawn

Web References: https://www.nature.com/articles/s41586-026-10846-4; https://www.stsci.edu/jwst/science-execution/program-information?id=5224; https://ista.ac.at/en/news/baby-quasars-growing-supermassive-black-holes/; https://www.mpg.de/25316826/black-hole-stars

References: Nature, DOI: 10.1038/s41586-026-10846-4; Astrophysical Journal Letters, DOI: 10.3847/2041-8213/ae7bfd

Image Credits: Illustration: Rohan Naidu, University of Hawai’i

Keywords

James Webb Space Telescope, JWST, black hole stars, supermassive black holes, little red dots, baby quasars, cosmic dawn, quasars, super-Eddington accretion, early Universe, astrophysics, Nature, MoM-BH*-1

The newly identified stream lies in UGC9050-Dw1, an ultra-diffuse galaxy, a remarkably faint and extended system whose stars are spread over a large area. Unlike bright spiral galaxies such as the Milky Way, ultra-diffuse galaxies contain relatively few stars for their size, making their light difficult to distinguish from the background sky. The stellar stream itself is even harder to see because it consists of stars gradually pulled away from a globular cluster. In images, it appears as a subtle trail stretching through the galaxy, a remnant of a long gravitational interaction that has been unfolding over time.

Globular clusters are dense, ancient systems containing thousands, and in some cases hundreds of thousands, of stars bound together by gravity. As a cluster orbits its host galaxy, the galaxy’s gravitational field exerts unequal forces across the cluster. The side facing the galactic centre experiences a slightly stronger pull than the far side, producing tidal stress. Over millions or billions of years, this process can remove individual stars from the cluster. The escaped stars do not immediately disperse randomly; instead, they continue following similar orbits, forming a narrow stellar stream that traces the cluster’s path through the galactic gravitational field.

That path carries information about the invisible mass shaping the galaxy. A stellar stream behaves like a gravitational test structure: its position, width, curvature and density reflect the forces acting on it. By modelling the stream’s orbit and the way it has been stretched, researchers can infer how much mass lies inside the galaxy and how that mass is distributed. Because most of a galaxy’s mass is not made of stars or gas, the stream becomes an indirect probe of its dark matter halo. Dark matter does not emit, absorb or reflect light, but its gravity influences the motion of visible matter, including stars in globular clusters and the streams they leave behind.

Julie Kiel Holm, a PhD student at the Niels Bohr Institute, and Sarah Pearson, an associate professor at DTU Space, led an international team that identified the structure in UGC9050-Dw1. Their analysis establishes that a method developed through studies of stellar streams in the Milky Way can be applied to a galaxy outside our own. The researchers used the stream’s observable properties to estimate the external galaxy’s mass distribution and dark matter content. Their results indicate that UGC9050-Dw1 contains a substantial amount of dark matter, consistent with earlier findings about ultra-diffuse galaxies, but obtained through an entirely different measurement technique.

The significance of the result extends beyond the discovery of one exceptionally faint line of stars. In the Milky Way, astronomers have used streams to search for irregularities in the dark matter distribution, including possible small-scale clumps that could disturb a stream’s otherwise smooth structure. Applying the same approach to other galaxies could reveal whether dark matter behaves similarly in environments with different sizes, shapes, star-formation histories and gravitational conditions. It could also help resolve a long-standing question surrounding ultra-diffuse galaxies: why do some appear to contain far more dark matter than their modest populations of stars would suggest?

Detecting the stream required overcoming two major challenges at once. The first was its intrinsic faintness. A globular cluster stream contains stars dispersed over a vast region, so its light is spread thinly across the sky. The second was the low surface brightness of the host galaxy itself. In such observations, the signal can easily be overwhelmed by foreground stars, background galaxies, instrumental effects and variations in the sky brightness. Sophisticated imaging and analysis methods are therefore essential. Researchers must distinguish a coherent, physically connected pattern from random alignments of unrelated stars or faint background features, then test whether the structure is consistent with a stream shaped by the galaxy’s gravitational field.

The discovery also offers a glimpse of what the next generation of astronomical surveys may uncover. The Euclid Space Telescope is designed to map billions of galaxies and investigate the large-scale distribution of matter, while NASA’s Nancy Grace Roman Space Telescope will deliver exceptionally sharp and wide-field observations of distant regions of the sky. Their data could reveal many more faint streams around external galaxies, creating a new population of targets for dark matter studies. Instead of relying almost exclusively on the Milky Way as a laboratory, astronomers may soon compare the gravitational structures of galaxies across a wide range of environments.

For Holm and her colleagues, the observation is therefore both a first and a proof of concept. A stellar stream born in a globular cluster has now been shown to survive as a detectable structure outside the Milky Way and to provide quantitative information about the dark matter halo of its host galaxy. The result turns an extraordinarily faint feature into a potential cosmic measuring instrument. As larger telescopes and more powerful data-analysis techniques expose the hidden outskirts of other galaxies, these fragile trails of stars could become one of the most revealing ways to investigate the unseen matter that governs the evolution of the Universe.

Subject of Research: Globular cluster stellar streams, ultra-diffuse galaxies and dark matter mapping beyond the Milky Way.

Article Title: Evidence for the first globular cluster stellar stream beyond the Milky Way

News Publication Date: 12-Aug-2026

Web References: Nature article; DOI: 10.1038/s41586-026-10878-w

References: Holm, J. K., Pearson, S., Nibauer, J., Sand, D. J., Price-Whelan, A. M., Starkenburg, T., Hendel, D. and Fielder, C., “Evidence for the first globular cluster stellar stream beyond the Milky Way,” Nature.

Image Credits: Hubble Space Telescope and Holm et al. (2026).

Keywords

Globular cluster stellar stream, dark matter, ultra-diffuse galaxy, UGC9050-Dw1, Hubble Space Telescope, Milky Way, stellar astronomy, galactic evolution, Euclid Space Telescope, Nancy Grace Roman Space Telescope

Researchers at the Surrey Space Centre found that radiation exposure can rise sharply at the altitudes used by most commercial aircraft, typically between 8 and 14 kilometres above the ground. At these heights, the atmosphere is thinner and provides less shielding from energetic particles arriving from space. Under ordinary conditions, aircraft occupants already receive more radiation than people at ground level, because cosmic rays collide with atmospheric molecules and generate secondary particles, including neutrons, that can penetrate aircraft cabins. During an extreme solar particle event or geomagnetic storm, however, the radiation environment can change within minutes or hours.

The most immediate biological concern is increased exposure to ionising radiation, which has enough energy to remove electrons from atoms and damage living tissue. A single severe event would not necessarily produce an acute radiation sickness risk for passengers, but it could substantially increase the dose received by flight crews, frequent travellers and aircraft operating repeatedly through affected regions. Measurements associated with a major solar storm in November 2025 showed radiation levels at high altitude briefly approaching ten times normal flight conditions. The researchers also compared present-day aviation conditions with the historic solar storm of February 1956, the strongest event in the modern record, concluding that passengers exposed during such an episode could receive a dose comparable to a year of routine flight-related cosmic radiation in a single journey.

For airlines, the threat may be even more serious inside the aircraft’s computers than inside its cabin. High-energy particles can pass through semiconductor devices and deposit electrical charge in sensitive circuits. This can produce a phenomenon known as a Single Event Upset, or SEU, in which a stored bit changes from zero to one or from one to zero, potentially altering a calculation, a command or a piece of data. Many SEUs are corrected automatically through redundancy, error-detecting codes or system resets. Yet during an intense particle event, the number of errors can rise from a few per hour to thousands, increasing pilot workload and creating the possibility that several supposedly independent systems could experience faults at the same time.

The vulnerability is growing as aircraft become more dependent on digital flight controls, networked computers and lightweight electronic components. Modern avionics are designed to withstand routine radiation environments, but extreme space weather can push systems beyond the conditions used in conventional certification and reliability testing. The issue became especially visible after Airbus temporarily grounded about 6,000 A320 aircraft after identifying a vulnerability to intense solar radiation in a flight-control computer. The weakness came to light following an incident in October 2025, when a JetBlue flight travelling from Cancún to Newark made an emergency landing in Florida. Although individual events do not prove that a solar storm caused a particular aircraft malfunction, the episode highlighted how radiation-induced errors can move from an invisible space-weather process to an operational aviation emergency.

The highest routine exposure occurs on polar routes, including services linking London Heathrow with Vancouver International Airport. Earth’s magnetic field normally deflects many charged particles away from the atmosphere, but its protective effect is weaker near the poles. Solar particles can therefore penetrate more deeply over high-latitude flight paths, where aircraft may already be operating in an environment with elevated radiation and reduced options for diversion. Severe geomagnetic storms can expand the affected region towards lower latitudes, however, meaning that the risk is not confined to polar aviation. During sufficiently powerful events, routes over the United Kingdom and other mid-latitude regions could also experience significant increases in radiation and electronic upset rates.

The research identifies a weakness in current aviation safety frameworks: existing procedures generally address normal occupational exposure and some known solar-particle alerts, but do not provide a consistent system for judging the combined effects of radiation dose and avionics disruption during an extreme event. An alert based only on low-energy protons can produce many warnings without a meaningful increase in the radiation environment at flight level. Professor Clive Dyer, a co-author of the study, said that current alerts generate at least ten false alarms for every true alert because they do not adequately represent the high-energy particles most relevant to aviation.

To improve decision-making, the Surrey team has proposed a new atmospheric radiation scale designed specifically for aircraft operations. Rather than relying on a single measurement, the scale combines high-energy proton observations from space with data from ground-level neutron monitors, including instruments at Surrey, Lerwick and Camborne. It is intended to connect the physical conditions in space with practical aviation consequences, including estimated human dose and the likelihood of SEUs in flight electronics. The researchers say that a graded system could allow airlines and regulators to move proportionately from increased monitoring to changes in altitude, route alterations, flight restrictions or temporary grounding, instead of reacting either too late or unnecessarily to ambiguous warnings.

The proposed framework is also intended to work with existing modelling and monitoring technologies. The team points to MAIRE, a radiation modelling system used to estimate aviation exposure, and SAIRA, an aircraft-based monitoring capability designed to measure the radiation environment during flight. Together with real-time space-weather observations, these tools could help operators determine whether a storm is likely to affect a particular route, how long the disruption may last and whether avoiding the affected region would be safer and more economical than continuing normally. The researchers emphasise that this kind of information must be integrated into flight planning systems rather than delivered as a specialist warning that arrives after an aircraft has already departed.

Dr Fan Lei, lead author of the study and a senior research fellow at the Surrey Space Centre, said the recent A320 grounding demonstrated that space weather is no longer a theoretical risk for aviation. As aircraft systems become more sophisticated and increasingly reliant on electronics, he argued, understanding the interaction between energetic particles, flight computers and human exposure will be essential to maintaining safety. Professor Keith Ryden, who co-authored the study, said the new scale could give operators a clearer basis for rapid decisions during extreme events. The researchers now hope their approach will support common international guidance, allowing airlines, aircraft manufacturers and regulators to respond to the next major solar storm with a shared understanding of when a warning should become an operational action.

Subject of Research:
The effects of extreme space weather on aviation radiation exposure, aircraft electronics, flight safety and operational decision-making.

Article Title:
Assessment of impacts to aviation radiation by extreme space weather events and new atmospheric radiation scales

News Publication Date:
11 August 2026

Web References:
https://doi.org/10.1051/swsc/2026025

References:
Lei, F., Dyer, C., Ryden, K. et al., “Assessment of impacts to aviation radiation by extreme space weather events and new atmospheric radiation scales,” Journal of Space Weather and Space Climate, DOI: 10.1051/swsc/2026025.

Keywords

Space weather, solar storms, aviation safety, cosmic radiation, atmospheric radiation, aircraft electronics, Single Event Upsets, avionics, polar flight routes, geomagnetic storms, aerospace engineering.

IRS 3 lies about 0.6 light-years from Sgr A*, a distance equivalent to roughly 42,000 times the separation between Earth and the Sun. In everyday terms, that is an immense distance. On the scale of the Galactic Centre, however, it places the star in the immediate neighbourhood of a black hole containing approximately four million times the mass of the Sun. The region is crowded with stars, powerful magnetic fields, energetic particles and rapidly changing radiation, making IRS 3 an exceptional natural laboratory for studying how stars evolve under extreme conditions.

The observations were conducted with the Mid-Infrared Instrument, or MIRI, aboard the James Webb Space Telescope. Mid-infrared light is particularly useful for investigating cool dust and molecules that absorb and re-emit radiation at characteristic wavelengths. By analysing the infrared spectrum of IRS 3, researchers led by PD Dr Florian Peißker of the University of Cologne identified the chemical and physical properties of the material surrounding the star with far greater detail than previous observations allowed.

What makes IRS 3 especially striking is the scale of its circumstellar envelope. The structure extends to a radius of approximately 10,000 astronomical units, where one astronomical unit is the average distance between Earth and the Sun. Such envelopes are common around mature, evolved stars, but IRS 3 appears to be unusually isolated in the immediate vicinity of Sgr A*. Its enormous shell of material therefore stands out against a dense background containing millions of other stars.

The new observations indicate that IRS 3 is undergoing a phase known as a superwind. This is a brief but dramatic stage in the late evolution of certain stars, particularly asymptotic giant branch stars. During this phase, powerful stellar winds carry gas and newly formed dust away from the star at extremely high rates. Over periods of only a few centuries, the star can lose a substantial fraction of its outer layers, transforming its surroundings into a thick, expanding envelope that will eventually disperse into interstellar space.

According to the research team, IRS 3 is losing material at a rate equivalent to the mass of Earth every 18 days. Although the comparison makes the scale easier to imagine, the total outflow is far more significant when considered over astronomical timescales. The steady loss of gas and dust explains why the envelope is both unusually large and dense. It also provides the raw material in which molecules can form, shielded within cooler regions of the expanding stellar outflow.

The detection of water is the most surprising aspect of the study. Near Sgr A*, ultraviolet radiation, X-rays and high-energy particles are expected to break apart fragile molecules. Water molecules can be destroyed when energetic photons dissociate them into their constituent atoms, particularly in exposed regions close to powerful sources of radiation. Yet the MIRI observations show that water exists within the envelope of IRS 3, suggesting that the dense outflow from the star creates protected pockets where molecular chemistry can proceed.

This discovery does not mean that the Galactic Centre is a calm or hospitable environment. Instead, it demonstrates that stellar mass loss can temporarily create its own chemical refuge. The material expelled by IRS 3 increases the density of gas and dust around the star, allowing some regions of the envelope to absorb damaging radiation. Within these shielded zones, atoms can combine on dust grains or in the gas phase, producing molecules that would otherwise be rapidly destroyed. The finding offers a new view of how evolved stars may enrich even the most violent regions of a galaxy.

The researchers say that IRS 3 may be actively supplying the area around Sgr A* with elements and molecules that later become part of the broader interstellar medium. Water itself is not evidence of life, but it is a crucial ingredient in planetary formation and a central component of the chemistry that precedes biology. As the envelope expands, some of its contents will eventually mix with surrounding gas, potentially influencing the composition of future stars, planets and smaller bodies formed in the Galactic Centre.

The study, published in Astronomy & Astrophysics, also highlights the scientific value of observing the Milky Way’s centre at infrared wavelengths. Visible light is heavily obscured by dust along the line of sight, while infrared radiation can pass through much of that material and reveal otherwise hidden structures. Future observations with METIS, a next-generation mid-infrared instrument being developed for the Extremely Large Telescope in Chile, could provide sharper views of IRS 3’s envelope, measure its winds in greater detail and determine how its molecular content changes over time. For now, the star’s unexpected water-rich cocoon is offering astronomers a rare glimpse of stellar chemistry unfolding beside one of the most extreme objects in the universe.

Subject of Research: Not applicable

Article Title: Dust production in the harsh environment of Sgr A* – MIRI/JWST observation of the O-rich asymptotic giant branch star IRS 3

News Publication Date: 11-Aug-2026

Web References: https://doi.org/10.1051/0004-6361/202660243

References: Astronomy & Astrophysics

Image Credits: ESO/F. Peissker

Keywords

James Webb Space Telescope, JWST, MIRI, IRS 3, Sagittarius A, Sgr A, Milky Way, Galactic Centre, water molecules, superwind, asymptotic giant branch star, stellar evolution, circumstellar envelope, dust production, black hole, infrared astronomy, Extremely Large Telescope

The assumption at the center of the study is known as the stellar initial mass function, or IMF. It describes the distribution of stellar masses produced during a generation of star formation. In a typical stellar population, high-mass stars are rare, while low-mass stars are far more numerous. Because massive stars are much brighter than their smaller counterparts, astronomers can often detect them in distant galaxies even when the faintest stars remain invisible. They then use the IMF to infer how many unseen low-mass stars must exist and calculate the total mass of the galaxy.

For more than half a century, researchers have commonly treated the IMF as universal. In this framework, a star-forming region in the Milky Way and a galaxy billions of light-years away are assumed to produce broadly similar proportions of massive and low-mass stars. That assumption makes it possible to convert the light from a galaxy into estimates of its stellar content. However, it also means that an incorrect IMF can systematically distort the measurements used to reconstruct the history of the cosmos.

The new research, led by scientists in the University of Missouri’s College of Arts and Science, indicates that the stellar mix can vary significantly between different environments. Rather than behaving as identical factories, star-forming regions may produce different proportions of stars depending on the physical conditions present when they collapse. Temperature, gas density, turbulence, chemical composition and the pressure within a molecular cloud could all influence how matter fragments into stars of different masses.

To investigate the possibility, the researchers turned to data from the European Space Agency’s Gaia mission. Gaia has created an extraordinarily detailed map of the Milky Way, measuring the positions, motions and other properties of nearly two billion stars. The Mizzou team focused on open and stellar clusters—groups of stars that formed from the same cloud at approximately the same time. Because cluster members share a common origin, they provide a natural laboratory for comparing stellar populations formed under related conditions.

If the IMF were truly universal, clusters should display essentially the same distribution of stellar masses after accounting for their ages and other effects. The researchers instead found meaningful differences from cluster to cluster. Some populations contained relative numbers of high- and low-mass stars that did not match the proportions predicted by a single universal IMF. The pattern was sufficiently consistent, the team reported, to suggest that the variation reflects differences in star-forming environments rather than random statistical noise or a simple observational error.

That result does not mean the IMF should be abandoned. Instead, the researchers propose that astronomers treat it as an environment-dependent tool. A galaxy dominated by dense, chemically enriched star-forming regions might require a different IMF from one where stars formed in more diffuse or metal-poor clouds. Applying the appropriate version could improve calculations of stellar mass, star-formation rates and the rate at which galaxies build up their visible matter over time.

The implications extend to some of the most surprising observations made by the James Webb Space Telescope. JWST has detected galaxies from the early universe that appear brighter and more massive than many theoretical models predicted. One possible explanation is that these galaxies grew more rapidly than expected, forcing scientists to reconsider aspects of cosmology and galaxy formation. Another possibility is that their stars formed with an unusual mass distribution. If early galaxies produced more massive, luminous stars than assumed, their light could make them appear to contain more stellar mass when interpreted through a standard IMF.

“Other galaxies weren’t breaking the laws of physics—we were measuring them with the wrong yardstick,” said Charles Steinhardt, an astronomy professor at the University of Missouri and co-author of the study. Undergraduate researcher Carter Meyerhoff, also a co-author, described the pattern as “surprisingly clean,” suggesting that astronomers may eventually be able to select an IMF based on the conditions in which a galaxy’s stars formed. The researchers emphasize that additional observations and independent analyses will be needed to establish how broadly the relationship applies beyond the Milky Way.

The study, titled “Direct evidence for stellar initial mass function variation in the Milky Way,” was published in The Astrophysical Journal Letters. Alexander Luening of the University of Rochester also contributed. By linking the birth environment of stars to the way astronomers interpret their combined light, the work points toward a more flexible model of the universe—one in which galaxies may not simply contain different numbers of stars, but may manufacture those stars according to different cosmic recipes.

Subject of Research: Stellar formation environments and variation in the stellar initial mass function across Milky Way star clusters.

Article Title: Direct evidence for stellar initial mass function variation in the Milky Way

Web References: University of Missouri College of Arts and Science: https://coas.missouri.edu/ ; Study DOI: https://doi.org/10.3847/2041-8213/ae7444

References: The Astrophysical Journal Letters, DOI: 10.3847/2041-8213/ae7444

Keywords

Stellar initial mass function, star formation, Milky Way, star clusters, Gaia mission, James Webb Space Telescope, galaxy evolution, stellar populations, astrophysics, astronomy