First transfer of behavior between species through single gene manipulation
Scientists strengthen brain cell connections to enable gift-giving courtship behavior in fruit flies.
Researchers in Japan have genetically transferred a unique courtship behavior from one fruit fly species to another. By turning on a single gene in insulin-producing neurons, the team successfully made a species of fruit fly (Drosophila melanogaster) perform a gift-giving ritual it had never done before. The study, published in the journal Science, represents the first example of manipulating a single gene to create new neural connections and transfer behavior between species.
Scientists have successfully transferred gift-giving courtship behavior from Drosophila subobscura to D. melanogaster males. They genetically engineered insulin-producing neurons in D. melanogaster to produce FruM proteins, causing these cells to grow long neural projections and connect to the courtship center in the brain. Picture Credits: Tanaka et al., 2025, CC BY
In nature, most male fruit flies court mates by rapidly vibrating their wings to create sound patterns or “courtship songs.” However, Drosophila subobscura has evolved a very different strategy: males regurgitate food and offer it as a gift to females during courtship. This behavior does not exist in closely related species such as D. melanogaster.
Drosophila subobscura males regurgitate food and offer it as a gift to females during courtship. Picture Credits: Tanaka et al., 2025, CC BY
These two fruit fly species diverged about 30-35 million years ago. Both have a gene called “fruitless” or “fru” that controls courtship behavior in males, but they use different strategies—one species sings and the other gives gifts. The researchers found the reason for this difference: in gift-giving flies (D. subobscura) insulin-producing neurons are connected to the courtship control center in the brain, while in singing flies (D. melanogaster) these cells remain disconnected.
“When we activated the fru gene in insulin-producing neurons of singing flies to produce FruM proteins, the cells grew long neural projections and connected to the courtship center in the brain, creating new brain circuits that produce gift-giving behavior in D. melanogaster for the first time,” Dr. Ryoya Tanaka, co-lead author and lecturer at Nagoya University’s Graduate School of Science, explained.
First transfer of courtship behavior between species of fruit flies, through single gene manipulation; the study is published in the journal Science. The researchers identified 16-18 insulin-producing neurons in Drosophila subobscura that express the male-specific protein FruM. When they activated FruM expression in insulin-producing neurons in D. melanogaster, these cells grew new neural connections and successfully transferred gift-giving courtship behavior to this species for the first time. Picture Credits: Tanaka et al., 2025, CC BY
The researchers inserted DNA into D. subobscura embryos to create flies with heat-activated proteins in specific brain cells. They used heat to activate groups of these cells and compared the brains of flies that did and did not regurgitate food. They identified 16-18 insulin-producing neurons that make the male-specific protein FruM, clustered in a part of the brain called the pars intercerebralis.
“Our findings indicate that the evolution of novel behaviors does not necessarily require the emergence of new neurons; instead, small-scale genetic rewiring in a few preexisting neurons can lead to behavioral diversification and, ultimately, contribute to species differentiation,” Dr. Yusuke Hara, co-lead author from the National Institute of Information and Communications Technology (NICT), noted.
“We’ve shown how we can trace complex behaviors like nuptial gift-giving back to their genetic roots to understand how evolution creates entirely new strategies that help species survive and reproduce,” senior author Dr. Daisuke Yamamoto from NICT said.
The study, “Cross-species implementation of an innate courtship behavior by manipulation of the sex-determinant gene” was published in the journal Science, on August 14, 2025, at DOI: 10.1126/science.adp5831. It represents the result of collaborative efforts led by Drs. Yusuke Hara and Daisuke Yamamoto at the National Institute of Information and Communications Technology (NICT), in partnership with researchers at Nagoya University.
Funding:
This research was conducted with support from KAKENHI Grant-in-Aid for Scientific Research: “Early-Career Scientists (Project Numbers: 19K16186, 21K15137),” “Scientific Research A (Project Number: 21H04790),” “Transformative Research Areas (A): Hierarchical Bio-Navigation Science (Project Numbers: 22H05650, 24H01433),” and “Scientific Research C (Project Number: 23K05846).”
Webb narrows atmospheric possibilities for Earth-sized exoplanet TRAPPIST-1 d
The exoplanet TRAPPIST-1 d intrigues astronomers looking for possibly habitable worlds beyond our solar system because it is similar in size to Earth, rocky, and resides in an area around its star where liquid water on its surface is theoretically possible. But according to a new study using data from the NASA/ESA/CSA James Webb Space Telescope, it does not have an Earth-like atmosphere.
A protective atmosphere, a friendly Sun, and lots of liquid water — Earth is a special place. Using the unprecedented capabilities of the Webb, astronomers are on a mission to determine just how special, and rare, our home planet is. Can this temperate environment exist elsewhere, even around a different type of star? The TRAPPIST-1 system provides a tantalizing opportunity to explore this question, as it contains seven Earth-sized worlds orbiting the most common type of star in the galaxy: a red dwarf.
“Ultimately, we want to know if something like the environment we enjoy on Earth can exist elsewhere, and under what conditions. While the James Webb Space Telescope is giving us the ability to explore this question in Earth-sized planets for the first time, at this point we can rule out TRAPPIST-1 d from a list of potential Earth twins or cousins,”
said Caroline Piaulet-Ghorayeb of the University of Chicago and Trottier Institute for Research on Exoplanets (IREx) at Université de Montréal, lead author of the study published in The Astrophysical Journal.
Planet TRAPPIST-1 d
The TRAPPIST-1 system is located 40 light-years away and was revealed as the record-holder for most Earth-sized rocky planets around a single star in 2017, thanks to data from NASA’s retired Spitzer Space Telescope and other observatories. Due to that star being a dim, relatively cold red dwarf, the “habitable zone” – where the planet’s temperature may be just right, such that liquid surface water is possible – lies much closer to the star than in our solar system. TRAPPIST-1 d, the third planet from the red dwarf star, lies on the cusp of that temperate zone, yet its distance to its star is only 2 percent of Earth’s distance from the Sun. TRAPPIST-1 d completes an entire orbit around its star, its year, in only four Earth days.
Webb’s NIRSpec (Near-Infrared Spectrograph) instrument did not detect molecules from TRAPPIST-1 d that are common in Earth’s atmosphere, like water, methane, or carbon dioxide. However, Piaulet-Ghorayeb outlined several possibilities for the exoplanet that remain open for follow-up study.
“There are a few potential reasons why we don’t detect an atmosphere around TRAPPIST-1 d. It could have an extremely thin atmosphere that is difficult to detect, somewhat like Mars. Alternatively, it could have very thick, high-altitude clouds that are blocking our detection of specific atmospheric signatures — something more like Venus. Or, it could be a barren rock, with no atmosphere at all,” Piaulet-Ghorayeb said.
The star TRAPPIST-1
No matter what the case may be for TRAPPIST-1 d, it’s tough being a planet in orbit around a red dwarf star. TRAPPIST-1, the host star of the system, is known to be volatile, often releasing flares of high-energy radiation with the potential to strip off the atmospheres of its small planets, especially those orbiting most closely. Nevertheless, scientists are motivated to seek signs of atmospheres on the TRAPPIST-1 planets because red dwarf stars are the most common stars in our galaxy. If planets can hold on to an atmosphere here, under waves of harsh stellar radiation, they could, as the saying goes, make it anywhere.
“Webb’s sensitive infrared instruments are allowing us to delve into the atmospheres of these smaller, colder planets for the first time,” said Björn Benneke of IREx at Université de Montréal, a co-author of the study. “We’re really just getting started using Webb to look for atmospheres on Earth-sized planets, and to define the line between planets that can hold onto an atmosphere, and those that cannot.”
The outer TRAPPIST-1 planets
Webb observations of the outer TRAPPIST-1 planets are ongoing, which hold both potential and peril. On the one hand, Benneke said, planets e, f, g, and h may have better chances of having atmospheres because they are further away from the energetic eruptions of their host star. However, their distance and colder environment will make atmospheric signatures more difficult to detect, even with Webb’s infrared instruments.
“All hope is not lost for atmospheres around the TRAPPIST-1 planets,” Piaulet-Ghorayeb said. “While we didn’t find a big, bold atmospheric signature at planet d, there is still potential for the outer planets to be holding onto a lot of water and other atmospheric components.” “Our detective work is just beginning. While TRAPPIST-1 d may prove a barren rock illuminated by a cruel red star, the outer planets TRAPPIST-1e, f, g, and h, may yet possess thick atmospheres,” added Ryan MacDonald, a co-author of the paper, now at the University of St Andrews in the United Kingdom, and previously at the University of Michigan. “Thanks to Webb we now know that TRAPPIST-1 d is a far cry from a hospitable world. We’re learning that the Earth is even more special in the cosmos.”
The James Webb Space Telescope narrows atmospheric possibilities for Earth-sized rocky exoplanet TRAPPIST-1 d. This artist’s concept depicts planet TRAPPIST-1 d passing in front of its turbulent star, with other members of the closely packed system shown in the background. The TRAPPIST-1 system is intriguing to scientists for a few reasons. Not only does the system have seven Earth-sized rocky worlds, but its star is a red dwarf, the most common type of star in the Milky Way galaxy. If an Earth-sized world can maintain an atmosphere here, and thus have the potential for liquid surface water, the chance of finding similar worlds throughout the galaxy is much higher. In studying the TRAPPIST-1 planets, scientists are determining the best methods for separating starlight from potential atmospheric signatures in data from the NASA/ESA/CSA James Webb Space Telescope. The star TRAPPIST-1’s variability, with frequent flares, provides a challenging testing ground for these methods. Credit: NASA, ESA, CSA, J. Olmsted (STScI)
WD 0525+526: Hubble uncovers rare white dwarf merger remnant
An international team of astronomers using the NASA/ESA Hubble Space Telescope have discovered a stellar rarity: an ultra-massive white dwarf that formed when a white dwarf merged with another star, rather than through the evolution of a single star. This discovery, which was made possible by Hubble’s sensitive ultraviolet observations, suggests that these rare white dwarfs may be more common than previously suspected.
A white dwarf is the end state for a star that is not massive enough to explode as a core-collapse supernova. The transition to a white dwarf begins when a star exhausts the supply of hydrogen in its core. The changes in and around the star’s core cause the star to expel its outer layers in a massive stellar sigh, revealing the star’s dense, Earth-sized core, which evolves into a white dwarf. The cores of white dwarfs are mostly composed of either carbon and oxygen or oxygen and neon, depending on the mass of the progenitor star. The Sun will become a white dwarf in about 5 billion years.
White dwarfs can theoretically have masses up to about 1.4 times the mass of the Sun, but white dwarfs that are more massive than the Sun are rare. These objects, which astronomers call ultra-massive white dwarfs, can form either through the evolution of a single massive star or through the merger of a white dwarf with another star.
Recently, astronomers used Hubble’s Cosmic Origins Spectrograph to investigate one such ultra-massive white dwarf, WD 0525+526. WD 0525+526 is just 128 light-years away and is 20% more massive than the Sun.
In visible light, the spectrum of WD 0525+526’s atmosphere resembled that of a typical white dwarf. However, Hubble’s ultraviolet spectrum revealed something unusual: evidence of carbon in the white dwarf’s atmosphere.
White dwarfs that form through the evolution of a single star have atmospheres composed of hydrogen and helium. These thick atmospheres blanket the carbon–oxygen or oxygen–neon surface of the white dwarf, usually preventing these elements from appearing in its spectrum.
When carbon appears in the spectrum of a white dwarf, it can signal a more violent origin than the typical single-star scenario: the collision of two white dwarfs, or of a white dwarf and a subgiant star. Such a collision can burn away the hydrogen and helium atmospheres of the colliding stars, leaving behind a scant layer of hydrogen and helium around the merger remnant that allows carbon from the white dwarf’s core to float upward, where it can be detected.
“It’s a discovery that underlines that things may be different from what they appear to us at first glance,” said the principal investigator of the Hubble programme, Boris Gaensicke, of the University of Warwick in the United Kingdom. “Until now, this appeared as a normal white dwarf, but Hubble’s ultraviolet eyes revealed that it had a very different history from what we would have guessed. It’s like asking a person you think you know well a different kind of question.”
This discovery marks the first time that a white dwarf born from colliding stars has been identified by its ultraviolet spectrum. Prior to this study, six white dwarf merger products were discovered via carbon lines in their visible-light spectra. All seven of these are part of a larger group that were found to be bluer than expected for their masses and ages from a study with ESA’s Gaia mission in 2019, with the evidence of mergers providing new insights into their formation history.
WD 0525+526 is remarkable even within the small group of white dwarfs known to be the product of merging stars. With a temperature of almost 21 000 kelvins and a mass of 1.2 solar masses, WD 0525+526 is hotter and more massive than the other white dwarfs in this group.
WD 0525+526’s extreme temperature posed something of a mystery for the team. For cooler white dwarfs, such as the six previously discovered merger products, a process called convection can mix carbon into the thin hydrogen–helium atmosphere. WD 0525+526 is too hot for convection to take place, however. Instead, the team determined that a more subtle process called semi-convection brings a small amount of carbon up into WD 0525+526’s atmosphere. WD 0525+526 has the smallest amount of atmospheric carbon of any white dwarf known to result from a merger, about 100 000 times less than other merger remnants.
The high temperature and low carbon abundance mean that identifying this white dwarf as the product of a merger would have been impossible without Hubble’s sensitivity to ultraviolet light; spectral lines from elements heavier than helium, like carbon, become fainter at visible wavelengths for hotter white dwarfs, but these spectral signals remain bright in the ultraviolet, where Hubble is uniquely positioned to spot them.
“Hubble’s Cosmic Origins Spectrograph is the only instrument that can obtain the superb quality ultraviolet spectroscopy that was required to detect the carbon in the atmosphere of this white dwarf,” said study lead Snehalata Sahu from the University of Warwick.
Because WD 0525+526’s unusual origin was revealed only once astronomers glimpsed its ultraviolet spectrum, it’s likely that other seemingly ‘normal’ white dwarfs are actually the result of cosmic collisions — a possibility that the team is excited to explore in the future.
“We would like to extend our research on this topic by exploring how common carbon white dwarfs are, and how many stellar mergers are hiding among the normal white dwarf family,” said study co-lead Antoine Bedrad from the University of Warwick. “That will be an important contribution to our understanding of white dwarf binaries, and the pathways to supernova explosions.”
This image is an illustration of a merging white dwarf remnant. An international team of astronomers using the NASA/ESA Hubble Space Telescope have discovered a stellar rarity: an ultra-massive white dwarf that formed when a white dwarf merged with another star, rather than through the evolution of a single star. This discovery, which was made possible by Hubble’s sensitive ultraviolet observations, suggests that these rare white dwarfs may be more common than previously suspected. Credit: NASA, ESA, R. Crawford (STScI)
Bibliographic information:
Sahu, S., Bédard, A., Gänsicke, B.T. et al. A hot white dwarf merger remnant revealed by an ultraviolet detection of carbon, Nat Astron (2025), DOI: https://doi.org/10.1038/s41550-025-02590-y
Webb finds new evidence for planet, a gas giant orbiting Alpha Centauri A, our closest solar twin
Astronomers using the NASA/ESA/CSA James Webb Space Telescope have found strong evidence of a giant planet orbiting a star in the stellar system closest to our own Sun. At just 4 light-years away from Earth, the Alpha Centauri triple star system has long been a compelling target in the search for worlds beyond our solar system.
This artist’s concept shows what the gas giant orbiting Alpha Centauri A could look like. Observations of the triple star system Alpha Centauri using the NASA/ESA/CSA James Webb Space Telescope indicate the potential gas giant, about the mass of Saturn, orbiting the star by about two times the distance between the Sun and Earth. In this concept, Alpha Centauri A is depicted at the upper left of the planet, while the other Sun-like star in the system, Alpha Centauri B, is at the upper right. Our Sun is shown as a small dot of light between those two stars. Credit: NASA, ESA, CSA, STScI, R. Hurt (Caltech/IPAC)
Visible only from Earth’s Southern hemisphere, it’s made up of the binary Alpha Centauri A and Alpha Centauri B, both Sun-like stars, and the faint red dwarf star Proxima Centauri. Alpha Centauri A is the third brightest star in the night sky. While there are three confirmed planets orbiting Proxima Centauri, the presence of other worlds surrounding Alpha Centauri A and Alpha Centauri B has proved challenging to confirm.
Now, Webb’s observations from its Mid-Infrared Instrument (MIRI) are providing the strongest evidence to date of a gas giant orbiting Alpha Centauri A. The results have been accepted in a series of two papers in The Astrophysical Journal Letters.
This image shows the Alpha Centauri star system from several different ground- and space-based observatories: the Digitized Sky Survey (DSS), the NASA/ESA Hubble Space Telescope, and the NASA/ESA/CSA James Webb Space Telescope. Alpha Centauri A is the third brightest star in the night sky, and the closest Sun-like star to Earth. The ground-based image from DSS shows the triple system as a single source of light, while Hubble resolves the two Sun-like stars in the system, Alpha Centauri A and Alpha Centauri B. The image from Webb’s MIRI (Mid-Infrared Instrument), which uses a coronagraphic mask to block the bright glare from Alpha Centauri A, reveals a potential planet orbiting the star. Credit: NASA, ESA, CSA, STScI, DSS, A. Sanghi (Caltech), C. Beichman (JPL), D. Mawet (Caltech), J. DePasquale (STScI)
If confirmed, the planet would be the closest to Earth that orbits in the habitable zone of a Sun-like star. However, because the planet candidate is a gas giant, scientists say it would not support life as we know it.
“With this system being so close to us, any exoplanets found would offer our best opportunity to collect data on planetary systems other than our own. Yet, these are incredibly challenging observations to make, even with the world’s most powerful space telescope, because these stars are so bright, close, and move across the sky quickly,” said Charles Beichman, NASA’s Jet Propulsion Laboratory and the NASA Exoplanet Science Institute at Caltech’s IPAC astronomy center, co-first author on the new papers. “Webb was designed and optimized to find the most distant galaxies in the universe. The operations team at the Space Telescope Science Institute had to come up with a custom observing sequence just for this target, and their extra effort paid off spectacularly.”
Several rounds of meticulously planned observations by Webb, careful analysis by the research team, and extensive computer modeling helped determine that the source seen in Webb’s image is likely to be a planet, and not a background object (like a galaxy), foreground object (a passing asteroid), or other detector or image artifact.
The first observations of the system took place in August 2024, using the coronagraphic mask aboard MIRI to block Alpha Centauri A’s light. While extra brightness from the nearby companion star Alpha Centauri B complicated the analysis, the team was able to subtract out the light from both stars to reveal an object over 10,000 times fainter than Alpha Centauri A, separated from the star by about two times the distance between the Sun and Earth.
While the initial detection was exciting, the research team needed more data to come to a firm conclusion. However, additional observations of the system in February 2025 and April 2025 (using Director’s Discretionary Time) did not reveal any objects like the one identified in August 2024.
“We are faced with the case of a disappearing planet! To investigate this mystery, we used computer models to simulate millions of potential orbits, incorporating the knowledge gained when we saw the planet, as well as when we did not,” said PhD student Aniket Sanghi of the California Institute of Technology in Pasadena, California. Sanghi is a co-first author on the two papers covering the team’s research.
This 3-panel image captures the NASA/ESA/CSA James Webb Space Telescope’s observational search for a planet around the nearest Sun-like star, Alpha Centauri A. The initial image shows the bright glare of Alpha Centauri A and Alpha Centauri B, then the middle panel shows the system with a coronagraphic mask placed over Alpha Centauri A to block its bright glare. However, the way the light bends around the edges of the coronagraph creates ripples of light in the surrounding space. The telescope’s optics (its mirrors and support structures) cause some light to interfere with itself, producing circular and spoke-like patterns. These complex light patterns, along with light from the nearby Alpha Centauri B, make it incredibly difficult to spot faint planets. In the panel at the right, astronomers have subtracted the known patterns (using reference images and algorithms) to clean up the image and reveal faint sources like the candidate planet. Credit: NASA, ESA, CSA, STScI, A. Sanghi (Caltech), C. Beichman (JPL), D. Mawet (Caltech), J. DePasquale (STScI)
Researchers say a non-detection in the second and third round of observations with Webb isn’t surprising.
“We found that in half of the possible orbits simulated, the planet moved too close to the star and wouldn’t have been visible to Webb in both February and April 2025,” said Sanghi.
Based on the brightness of the planet in the mid-infrared observations and the orbit simulations, researchers say it could be a gas giant approximately the mass of Saturn orbiting Alpha Centauri A in an elliptical path varying between 1 to 2 times the distance between Sun and Earth.
“These are some of the most demanding observations we’ve done so far with MIRI’s coronagraph,” said Pierre-Olivier Lagage, of CEA, France, who is a co-author on the papers and was the French lead for the development of MIRI. “When we were developing the instrument we were eager to see what we might find around Alpha Centauri, and I’m looking forward to what it will reveal to us next!”
“If confirmed, the potential planet seen in the Webb image of Alpha Centauri A would mark a new milestone for exoplanet imaging efforts,” Sanghi says. “Of all the directly imaged planets, this would be the closest to its star seen so far. It’s also the most similar in temperature and age to the giant planets in our solar system, and nearest to our home, Earth,” he says. “Its very existence in a system of two closely separated stars would challenge our understanding of how planets form, survive, and evolve in chaotic environments.”
If confirmed by additional observations, the team’s results could transform the future of exoplanet science.
“This would become a touchstone object for exoplanet science, with multiple opportunities for detailed characterization by Webb and other observatories,” said Beichman.
Hubble makes size estimate of interstellar comet 3I/ATLAS
A team of astronomers has taken the sharpest-ever picture of the unexpected interstellar comet 3I/ATLAS, using the crisp vision of the NASA/ESA Hubble Space Telescope.
This image of interstellar comet 3I/ATLAS was captured by the Hubble Space Telescope’s Wide Field Camera on 21 July 2025. The scale bar is labeled in arcseconds, which is a measure of angular distance on the sky. One arcsecond is equal to an angular measurement of 1/3600 of one degree. There are 60 arcminutes in a degree and 60 arcseconds in an arcminute (the full Moon has an angular diameter of about 30 arcminutes). The actual size of an object that covers one arcsecond on the sky depends on its distance from the telescope. The north and east compass arrows show the orientation of the image on the sky. Note that the relationship between north and east on the sky (as seen from below) is flipped relative to direction arrows on a map of the ground (as seen from above). This image shows visible wavelengths of light. Credit: NASA, ESA, D. Jewitt (UCLA); Image Processing: J. DePasquale (STScI)
Hubble’s observations are allowing astronomers to more accurately estimate the size of the comet’s solid icy nucleus. The upper limit on the diameter of the nucleus is 5.6 kilometers, though it could be as small as 320 metres across, researchers report. Though the Hubble images put tighter constraints on the nucleus size compared to previous ground-based estimates, the solid heart of the comet presently cannot be directly seen, even by Hubble. Observations from other observatories, including the NASA/ESA/CSA James Webb Space Telescope, will help refine our knowledge about the comet, including its chemical makeup.
Hubble also captured a dust plume ejected from the Sun-warmed side of the comet, and the hint of a dust tail streaming away from the nucleus. Hubble’s data yields a dust-loss rate consistent with comets that are first detected around 480 million kilometres from the Sun. This behaviour is much like the signature of previously seen Sun-bound comets originating within our Solar System.
The big difference is that this interstellar visitor originated in some other Solar System elsewhere in our Milky Way galaxy.
3I/ATLAS is traveling through our Solar System at roughly 210,000 kilometres per hour, the highest velocity ever recorded for a Solar System visitor. This breathtaking sprint is evidence that the comet has been drifting through interstellar space for many billions of years. The gravitational slingshot effect from innumerable stars and nebulae the comet passed added momentum, ratcheting up its speed. The longer 3I/ATLAS was out in space, the higher its speed grew.
This comet was discovered by the Asteroid Terrestrial-impact Last Alert System (ATLAS) on 1 July 2025 at a distance of 675 million kilometres from the Sun. 3I/ATLAS should remain visible to ground-based telescopes through September, after which it will pass too close to the Sun to observe and is expected to reappear on the other side of the Sun by early December.
The paper will be published in The Astrophysical Journal Letters. It is already available here.
This is a Hubble Space telescope image of the interstellar comet 3I/ATLAS. Hubble photographed the comet on 21 July 21 2025, when the comet was 365 million kilometres from Earth. Hubble shows that the comet has a teardrop-shaped cocoon of dust coming off its solid, icy nucleus. Because Hubble was tracking the comet moving along a hyperbolic trajectory, the stationary background stars are streaked in the exposure. Credit: NASA, ESA, D. Jewitt (UCLA); Image Processing: J. DePasquale (STScI)
From Italy, two new solutions for coral protection: a conductive biopaste and a healing patch
Innovative solutions for reef conservation emerge from the collaboration between the University of Milano-Bicocca, the Istituto Italiano di Tecnologia, and the Acquario di Genova.
The results are an intelligent material to accelerate coral growth and another to treat infectious diseases. They are made of natural materials that, once degraded, do not harm the marine ecosystem.
The two solutions, tested on real corals at the aquarium, have been described in international journals Advanced Materials and One Earth.
Milan/Genoa (Italy), July 30, 2025 – A research group in Italy has developed two new coral protection technologies for healing and restoring coral reefs: a biopaste and a natural patch, both successfully tested on real corals. The two solutions resulted from the collaboration among researchers at the University of Milano-Bicocca in Milan, the Istituto Italiano di Tecnologia (IIT-Italian Institute of Technology) in Genoa, and the Acquario di Genova (Aquarium of Genoa).
Threatened by climate change and increasingly vulnerable, coral reefs are crucial ecosystems for marine biodiversity and the survival of many coastal communities. In addition to being a fundamental resource for fishing and tourism, reefs play a key role in global ecological balance. To counteract their progressive degradation, scientific research is focusing on innovative solutions that combine eco-compatibility, effectiveness, and rapid intervention.
The first solution realized by the research group is a green, fully biodegradable biopaste capable of anchoring corals while simultaneously accelerating their growth through electrochemical mineralization technology. Described in a study published in the journal Advanced Materials, the new material, named “Active Biopaste”, is a paste made from modified soybean oil and graphene. The two substances, once mixed, harden in a controllable way and become a solid, conductive substrate to anchor coral fragments and support Mineral AccretionTechnology(MAT), a technique that stimulates their growth. The paste exhibits stable properties for over 40 days in seawater, and MAT tests show significant enhancement of coral growth rates within two weeks, doubling those of the control group.
“What makes our solution unique is the integration of two essential functions into a single innovative material,” explains Gabriele Corigliano, first author of the study and a PhD student in Marine Sciences at Bicocca and in the Smart Materials unit at IIT, coordinated by Athanassia Athanassiou. “On one hand, this paste simplifies the attachment of corals, making it safer and more reliable both in underwater nurseries and on the reef. On the other hand, thanks to its conductive properties, it promotes coral growth through MAT, a technique that uses low-intensity electric currents to deposit calcium carbonate on metal structures—this is the material corals use to build their skeletons. Unlike traditional MAT, no permanent structures are needed, eliminating the risk of corrosion and long-term pollution. Overall, our approach actively promotes coral growth and is safe for marine life.”
“We aim to push current knowledge in materials science as far as possible to produce technologies that are effective and multifunctional underwater, while also respecting the environment and aligning with the United Nations’ sustainability goals,” adds Marco Contardi, researcher at the MaRHE Center at Bicocca and member of the Smart Materials unit at IIT. “This approach allows us to design materials intended for the sea and for marine use, always considering their effects during and after application, such as biodegradation.”
“This study highlights the profound transformation underway in marine sciences,” notes Simone Montano, associate professor in the Department of Environmental and Earth Sciences and deputy director of the MaRHE Center at the University of Milano-Bicocca. “The synergy between the three research groups—the MaRHE Center at the University of Milano-Bicocca, the IIT Smart Materials team, and the Aquarium of Genoa—demonstrates how the development of innovative and sustainable technologies can buy us the time needed for mitigation policies to take effect. Only through joint efforts like this can we give nature the chance to return to its original balance.”
This same collaboration also led to a second major contribution to reef conservation, published in the journal One Earth. First author of this study is VincenzoScribano, a PhD student at the University of Milano-Bicocca and member of the Smart Materials unit at IIT, who developed an eco-compatible system for the targeted delivery of antibiotics to diseased corals—a sort of patch combining a hydrophilic film loaded with antibiotics (made from chitosan, a polymer derived from shellfish) with a natural hydrophobic sealant based on beeswax and plant oils from sunflower and flax. All materials are natural and, once degraded, do not harm the marine ecosystem. In aquarium tests, the treatment halted the disease’s progression in over 90% of the cases.
“This technology allows us to treat corals affected by aggressive diseases that damage their tissue and spread rapidly across coral reefs,” explains Scribano. “Thanks to the dual-layer system, the antibiotics are released exclusively on the infected coral area, and the delivery is sealed off by the paste, preventing the spread of antibiotics into the marine environment. The technology has proven particularly effective against a disease in the tissue necrosis family, which is widespread in aquaculture.”
“With these studies, we’ve demonstrated the potential of a responsible approach to materials design,” says Athanassia Athanassiou, Principal Investigator and Head of the Smart Materials unit at IIT. “The goal is to develop sustainable solutions that support living organisms and protect biodiversity. We conduct in-depth research on sustainable materials, evaluating their effectiveness and end-of-life impact, always with a design approach that considers environmental consequences. Today, every design decision we make is guided by a responsible and sustainable scientific vision.”
These results are part of a long-term research initiative by the joint team from the University of Milano-Bicocca, IIT, and the Aquarium of Genoa, which has become an international reference point in the development of coral conservation technologies. This interdisciplinary approach has already led to previous innovations, such as the use of curcumin, a natural antioxidant extracted from turmeric, to reduce coral bleaching.
Materials and innovations are tested at the MaRHE Center facility within the Aquarium of Genoa, which, thanks to its solid expertise in the field, controlled environment, and attention to animal welfare, is an ideal setting for developing solutions aimed at marine conservation. This integrated vision sees the sea not only as an ecosystem to protect but also as a laboratory for imagining a more sustainable future in harmony with the environment.
Webb traces details of complex planetary nebula – More than one star contributes to the irregular shape of NGC 6072
Webb’s newest look at planetary nebula NGC 6072 in the near- and mid-infrared shows what may appear as a very messy scene resembling splattered paint. However, the unusual, asymmetrical scene hints at more complicated mechanisms underway, as the star central to the scene approaches the very final stages of its life and expels shells of material, losing up to 80 percent of its mass.
Since their discovery in the late 1700s, astronomers have learned that planetary nebulae, or the expanding shell of glowing gas expelled by a low-intermediate mass star late in its life, can come in all shapes and sizes. Most planetary nebulae present as circular, elliptical, or bi-polar, but some stray from the norm, as seen in new high-resolution images of the planetary nebula NGC 6072 by the NASA/ESA/CSA James Webb Space Telescope.
The NASA/ESA/CSA James Webb Space Telescope’s view of planetary nebula NGC 6072 in the near-infrared shows a complex scene of multiple outflows expanding out at different angles from a dying star at the centre of the scene. These outflows push gas toward the equatorial plane, forming a disc. Astronomers suspect there is at least one other star interacting with the material cast off by the central dying star, creating the abnormal appearance of this planetary nebula. In this image, the red areas represent cool molecular gas, for example, molecular hydrogen. Credit: NASA, ESA, CSA, STScI
In Webb’s NIRCam (Near-Infrared Camera) view of the object, it’s readily apparent that this nebula is multi-polar. This means there are several different elliptical outflows jetting out either way from the centre. These outflows compress gas towards the equatorial plane and create a disc. Astronomers say this is evidence that there are likely at least two stars at the centre of this scene. Specifically, a companion star is interacting with an aging star that had already begun to shed some of its outer layers of gas and dust.
The central region of the planetary nebula glows from the hot stellar core, seen as a light blue hue in near-infrared light. The dark orange material, which is made up of gas and dust, follows pockets or open areas that appear dark blue. This clumpiness could be created when dense molecules formed while being shielded from hot radiation from the central star. There could also be a time element at play. Over thousands of years, inner fast winds could be ploughing through the halo cast off from the main star when it first started to lose mass.
The mid-infrared view of planetary nebula NGC 6072 from the NASA/ESA/CSA James Webb Space Telescope shows expanding circular shells around the outflows from the dying central star, which astronomers suspect is that pinkish white dot at the centre of the image. The longer wavelengths captured by Webb’s MIRI (Mid-Infrared Instrument) highlight the dust being cast off by the central dying star. In this image, the blue represents cool molecular gas seen in red in the image from Webb’s NIRCam (Near-Infrared Camera) due to colour mapping. Credit: NASA, ESA, CSA, STScI
The longer wavelengths captured by Webb’s MIRI (Mid-Infrared Instrument) are highlighting dust, revealing the star researchers suspect could be central to this scene. It appears as a small pink-white dot in this image. Webb’s look in the mid-infrared wavelength also reveals concentric rings expanding from the central region, the most obvious circling just past the edges of the lobes.
This may be additional evidence of a secondary star at the centre of the scene hidden from our view. The secondary star, as it circles repeatedly around the original star, could have carved out rings of material in a spiral pattern as the main star was expelling mass during an earlier stage of its life.
The red areas in NIRCam and blue areas in MIRI both trace cool molecular gas (likely molecular hydrogen) while central regions trace hot ionized gas.
Planetary nebulae will remain a topic of study for astronomers using Webb who hope to learn more about the full life cycle of stars and how they impact their surrounding environments. As the star at the centre of a planetary nebula cools and fades, the nebula will gradually dissipate into the interstellar medium — contributing enriched material that helps form new stars and planetary systems, now containing those heavier elements.
Webb’s imaging of NGC 6072 opens the door to studying how the planetary nebulae with more complex shapes contribute to this process.
This image of NGC 6072, captured by the James Webb Space Telescope’s NIRCam (Near-Infrared Camera), shows compass arrows, scale bar, and colour key for reference. The north and east compass arrows show the orientation of the image on the sky. Note that the relationship between north and east on the sky (as seen from below) is flipped to the direction arrows on a map of the ground (as seen from above). The scale bar is labeled in light-years, which is the distance that light travels in one Earth-year (it takes 0.5 years for light to travel a distance equal to the length of the scale bar). One light-year is equal to about 9.46 trillion kilometers. This image shows invisible near-infrared wavelengths of light that have been translated into visible-light colours. The colour key shows which NIRCam filters were used when collecting the light. The colour of each filter name is the visible light colour used to represent the infrared light that passes through that filter. Credit: NASA, ESA, CSA, STScI
Astronomers witness still-forming planet sculpting the dust around it, near the star HD 135344B
The image to the left, taken with ESO’s Very Large Telescope (VLT), shows a possible planet being born around the young star HD 135344B. This star, located around 440 light-years away, is surrounded by a disc of dust and gas with prominent spiral arms. Theory predicts that planets can sculpt spiral arms like these, and the new planet candidate is located at the base of one of the arms, just as expected. The image was captured with a new VLT instrument: the Enhanced Resolution Imager and Spectrograph (ERIS). The central black circle corresponds to a coronagraph –– a device that blocks the light of the star to reveal faint details around it. The white circle indicates the location of the planet. The image to the right is a combination of previous observations taken with the SPHERE instrument also at the VLT (red) and the Atacama Large Millimeter/submillimeter Array (ALMA, orange and blue). These and other previous studies of HD 135344B did not find signatures of a companion, but ERIS may have finally unveiled the culprit responsible for the star’s spiral disc. Credit: ESO/F. Maio et al./T. Stolker et al./ ALMA (ESO/NAOJ/NRAO)/N. van der Marel et al.
Astronomers may have caught a still-forming planet in action, carving out an intricate pattern in the gas and dust that surrounds its young host star. Using ESO’s Very Large Telescope (VLT), they observed a planetary disc with prominent spiral arms, finding clear signs of a planet nestled in its inner regions. This is the first time astronomers have detected a planet candidate embedded inside a disc spiral.
“We will never witness the formation of Earth, but here, around a young star 440 light-years away, we may be watching a planet come into existence in real time,” says Francesco Maio, a doctoral researcher at the University of Florence, Italy, and lead author of this study, published today in Astronomy & Astrophysics.
The potential planet-in-the-making was detected around the star HD 135344B, within a disc of gas and dust around it called a protoplanetary disc. The budding planet is estimated to be twice the size of Jupiter and as far from its host star as Neptune is from the Sun. It has been observed shaping its surroundings within the protoplanetary disc as it grows into a fully formed planet.
This image, taken with ESO’s Very Large Telescope (VLT), shows a spiral disc around the young star HD 135344B. The image was obtained with the VLT’s Enhanced Resolution Imager and Spectrograph (ERIS) instrument, which found a candidate planet that may be sculpting the spiral features in the disc. The location of this planet is indicated with a white circle. The central black circle corresponds to a coronagraph — a device that blocks the light of the star to reveal faint details around it. Credit: ESO/F. Maio et al.
Protoplanetary discs have been observed around other young stars, and they often display intricate patterns, such as rings, gaps or spirals. Astronomers have long predicted that these structures are caused by baby planets, which sweep up material as they orbit around their parent star. But, until now, they had not caught one of these planetary sculptors in the act.
This image, captured with ESO’s Very Large Telescope (VLT), shows a spiral disc around the young star HD 135344B. The image, which was released in 2016, was obtained with the Spectro-Polarimetric High-contrast Exoplanet Research (SPHERE) instrument.
Spiral features like these can be sculpted by planets, although this image doesn’t show evidence of companions orbiting HD 135344B. However, new observations at somewhat longer wavelengths, obtained with the Enhanced Resolution Imager and Spectrograph (ERIS) at the VLT, have found a possible young planet around this star.
The central black circle corresponds to a coronagraph –– a device that blocks the light of the star to reveal faint details around it.
Credit: ESO/T. Stolker et al.
This image, taken with the Atacama Large Millimeter/submillimeter Array (ALMA), and first released in 2015, shows a planet-forming disc around the young star HD 135344B. The image combines a view of both the gas (blue) and the dust (orange) around the star. The star itself is invisible at these wavelengths, and is located in the central gap of the disc.
Credit: ALMA (ESO/NAOJ/NRAO)/N. van der Marel et al.
This image shows the dusty disc around the young star HD 135344B. It’s a combination of data taken with two different facilities: the Spectro-Polarimetric High-contrast Exoplanet Research (SPHERE) instrument at ESO’s VLT in red, and the Atacama Large Millimeter/submillimeter Array (ALMA) in orange and blue. The original SPHERE and ALMA images were released in 2016 and 2015 respectively and didn’t show evidence for the presence of a planet in this disc, first revealed in 2025.
Credit: ESO/T. Stolker et al./ALMA (ESO/NAOJ/NRAO)/N. van der Marel et al.
This image from the Digitized Sky Survey (DSS) shows the region of the sky around the star HD 135344B. Right at the centre of the image there are two bright stars close to each other; HD 135344B is the one at the bottom.
Credit: ESO/Digitized Sky Survey 2. Acknowledgement: D. De Martin
This image shows a possible companion orbiting the young star V960 Mon. The star, located more than 5000 light-years away, is surrounded by a disc with intricate features. Previous analysis of the disc showed that it contains clumps of unstable material that could collapse to form a companion object. The new candidate found here could be either a planet or a brown dwarf –– an object bigger than a planet that didn’t gain enough mass to shine as a star.
The candidate object was found with ESO’s Very Large Telescope (VLT), using its new Enhanced Resolution Imager and Spectrograph (ERIS). The new ERIS data are shown here in orange, overlaid on older images of the dusty disc as seen with the VLT’s SPHERE instrument (yellow) and the Atacama Large Millimeter/submillimeter Array (ALMA, in blue).
Credit: ESO/A. Dasgupta/ALMA (ESO/NAOJ/NRAO)/Weber et al.
This image, taken with ESO’s Very Large Telescope (VLT), shows a possible companion orbiting the young star V960 Mon. The image was captured with the VLT’s Enhanced Resolution Imager and Spectrograph (ERIS) instrument. The properties of the object are unknown: it could be a planet or a brown dwarf –– an object bigger than a planet that didn’t gain enough mass to shine as a star.
Credit: ESO/A. Dasgupta
In the case of HD 135344B’s disc, swirling spiral arms had previously been detected by another team of astronomers using SPHERE (Spectro-Polarimetric High-contrast Exoplanet REsearch), an instrument on ESO’s VLT. However, none of the previous observations of this system found proof of a planet forming within the disc.
Now, with observations from the new VLT’s Enhanced Resolution Imager and Spectrograph (ERIS) instrument, the researchers say they may have found their prime suspect. The team spotted the planet candidate right at the base of one of the disc’s spiral arms, exactly where theory had predicted they might find the planet responsible for carving such a pattern.
“What makes this detection potentially a turning point is that, unlike many previous observations, we are able to directly detect the signal of the protoplanet, which is still highly embedded in the disc,” says Maio, who is based at the Arcetri Astrophysical Observatory, a centre of Italy’s National Institute for Astrophysics (INAF). “This gives us a much higher level of confidence in the planet’s existence, as we’re observing the planet’s own light.”
A star’s companion is born
A different team of astronomers have also recently used the ERIS instrument to observe another star, V960 Mon, one that is still in the very early stages of its life. In a study published on 18 July in The Astrophysical Journal Letters, the team report that they have found a companion object to this young star. The exact nature of this object remains a mystery.
This image shows a possible companion orbiting the young star V960 Mon. The star, located more than 5000 light-years away, is surrounded by a disc with intricate features. Previous analysis of the disc showed that it contains clumps of unstable material that could collapse to form a companion object. The new candidate found here could be either a planet or a brown dwarf –– an object bigger than a planet that didn’t gain enough mass to shine as a star.
The candidate object was found with ESO’s Very Large Telescope (VLT), using its new Enhanced Resolution Imager and Spectrograph (ERIS). The new ERIS data are shown here in orange, overlaid on older images of the dusty disc as seen with the VLT’s SPHERE instrument (yellow) and the Atacama Large Millimeter/submillimeter Array (ALMA, in blue).
Credit: ESO/A. Dasgupta/ALMA (ESO/NAOJ/NRAO)/Weber et al.
This image, taken with ESO’s Very Large Telescope (VLT), shows a possible companion orbiting the young star V960 Mon. The image was captured with the VLT’s Enhanced Resolution Imager and Spectrograph (ERIS) instrument. The properties of the object are unknown: it could be a planet or a brown dwarf –– an object bigger than a planet that didn’t gain enough mass to shine as a star.
Credit: ESO/A. Dasgupta
The new study, led by Anuroop Dasgupta, a doctoral researcher at ESO and at the Diego Portales University in Chile, follows up observations of V960 Mon made a couple of years ago. Those observations, made with both SPHERE and the Atacama Large Millimeter/submillimeter Array (ALMA), revealed that the material orbiting V960 Mon is shaped into a series of intricate spiral arms. They also showed that the material is fragmenting, in a process known as ‘gravitational instability’, when large clumps of the material around a star contract and collapse, each with the potential to form a planet or a larger object.
“That work revealed unstable material but left open the question of what happens next. With ERIS, we set out to find any compact, luminous fragments signalling the presence of a companion in the disc — and we did,” says Dasgupta.
The team found a potential companion object very near to one of the spiral arms observed with SPHERE and ALMA. The team say that this object could either be a planet in formation, or a ‘brown dwarf’ — an object bigger than a planet that didn’t gain enough mass to shine as a star.
If confirmed, this companion object may be the first clear detection of a planet or brown dwarf forming by gravitational instability.
More information
This research highlighted in the first part of this release was presented in the paper “Unveiling a protoplanet candidate embedded in the HD 135344B disk with VLT/ERIS” to appear in Astronomy & Astrophysics (doi: 10.1051/0004-6361/202554472). The second part of the release highlights the study “VLT/ERIS observations of the V960 Mon system: a dust-embedded substellar object formed by gravitational instability?” published in The Astrophysical Journal Letters (doi: 10.3847/2041-8213/ade996).
The team who conducted the first study (on HD 135344B) is composed of F. Maio (University of Firenze, Italy, and INAF-Osservatorio Astrofisico Arcetri, Firenze, Italy [OAA]), D. Fedele (OAA), V. Roccatagliata (University of Bologna, Italy [UBologna] and OAA), S. Facchini (University of Milan, Italy [UNIMI]), G. Lodato (UNIMI), S. Desidera (INAF-Osservatorio Astronomico di Padova, Italy [OAP]), A. Garufi (INAF – Istituto di Radioastronomia, Bologna, Italy [INAP-Bologna], and Max-Planck-Institut für Astronomie, Heidelberg, Germany [MPA]), D. Mesa (OAP), A. Ruzza (UNIMI), C. Toci (European Southern Observatory [ESO], Garching bei Munchen, Germany, and OAA), L. Testi (OAA, and UBologna), A. Zurlo (Diego Portales University [UDP], Santiago, Chile, and Millennium Nucleus on Young Exoplanets and their Moons [YEMS], Santiago, Chile), and G. Rosotti (UNIMI).
The team behind the second study (on V960 Mon) is primarily composed of members of the Millennium Nucleus on Young Exoplanets and their Moons (YEMS), a collaborative research initiative based in Chile. Core YEMS contributors include A. Dasgupta (ESO, Santiago, Chile, UDP, and YEMS), A. Zurlo (UDP and YEMS), P. Weber (University of Santiago [Usach], Chile, and YEMS, and Center for Interdisciplinary Research in Astrophysics and Space Exploration [CIRAS], Santiago, Chile), F. Maio (OAA, and University of Firenze, Italy), Lucas A. Cieza (UDP and YEMS), D. Fedele (OAA), A. Garufi (INAF Bologna and MPA), J. Miley (Usach, YEMS, and CIRAS), P. Pathak (Indian Institute of Technology, Kanpur, India), S. Pérez (Usach and YEMS, and CIRAS), and V. Roccatagliata (UBologna and OAA).
The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of ESO, the U.S. National Science Foundation (NSF) and the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Republic of Chile. ALMA is funded by ESO on behalf of its Member States, by NSF in cooperation with the National Research Council of Canada (NRC) and the National Science and Technology Council (NSTC) in Taiwan and by NINS in cooperation with the Academia Sinica (AS) in Taiwan and the Korea Astronomy and Space Science Institute (KASI). ALMA construction and operations are led by ESO on behalf of its Member States; by the National Radio Astronomy Observatory (NRAO), managed by Associated Universities, Inc. (AUI), on behalf of North America; and by the National Astronomical Observatory of Japan (NAOJ) on behalf of East Asia. The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.
The European Southern Observatory (ESO) enables scientists worldwide to discover the secrets of the Universe for the benefit of all. We design, build and operate world-class observatories on the ground — which astronomers use to tackle exciting questions and spread the fascination of astronomy — and promote international collaboration for astronomy. Established as an intergovernmental organisation in 1962, today ESO is supported by 16 Member States (Austria, Belgium, Czechia, Denmark, France, Finland, Germany, Ireland, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom), along with the host state of Chile and with Australia as a Strategic Partner. ESO’s headquarters and its visitor centre and planetarium, the ESO Supernova, are located close to Munich in Germany, while the Chilean Atacama Desert, a marvellous place with unique conditions to observe the sky, hosts our telescopes. ESO operates three observing sites: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope and its Very Large Telescope Interferometer, as well as survey telescopes such as VISTA. Also at Paranal ESO will host and operate the Cherenkov Telescope Array South, the world’s largest and most sensitive gamma-ray observatory. Together with international partners, ESO operates ALMA on Chajnantor, a facility that observes the skies in the millimetre and submillimetre range. At Cerro Armazones, near Paranal, we are building “the world’s biggest eye on the sky” — ESO’s Extremely Large Telescope. From our offices in Santiago, Chile we support our operations in the country and engage with Chilean partners and society.
Gemini North Discovers Long-Predicted Stellar Companion of Betelgeuse?
Gemini North telescope in Hawai‘i reveals never-before-seen companion to Betelgeuse, solving millennia-old mystery
Gemini North Discovers Long-Predicted Stellar Companion of Betelgeuse. Using the NASA-NSF-funded ‘Alopeke instrument on the Gemini North telescope, one half of the International Gemini Observatory, partly funded by the U.S. National Science Foundation (NSF) and operated by NSF NOIRLab, astronomers have discovered a companion star in an incredibly tight orbit around Betelgeuse. This discovery answers the millennia-old question of why this famous star experiences a roughly six-year-long periodic change in its brightness, and provides insight into the physical mechanisms behind other variable red supergiants. The companion star appears blue here because, based on the team’s analysis, it is likely an A- or B-type star, both of which are blue-white due to their high temperatures. ‘Alopeke is funded by the NASA-NSF Exoplanet Observational Research Program (NN-EXPLORE). Credit: International Gemini Observatory/NOIRLab/NSF/AURA Image Processing: M. Zamani (NSF NOIRLab)
Please notice that, according to the published studies, Betelgeuse’s companion might not be a star.
Astronomers have discovered a companion star in an incredibly tight orbit around Betelgeuse using the NASA and U.S. National Science Foundation-funded ‘Alopeke instrument on Gemini North, one half of the International Gemini Observatory, partly funded by the NSF and operated by NSF NOIRLab. This discovery answers the longstanding mystery of the star’s varying brightness and provides insight into the physical mechanisms behind other variable red supergiants.
Photo of the constellation Orion with annotations from IAU and Sky & Telescope. Credit: E. Slawik/NOIRLab/NSF/AURA/M. Zamani
Betelgeuse is one of the brightest stars in the night sky, and the closest red supergiant to Earth. It has an enormous volume, spanning a radius around 700 times that of the Sun. Despite only being ten million years old, which is considered young by astronomy standards, it’s late in its life. Located in the shoulder of the constellation Orion, people have observed Betelgeuse with the naked eye for millennia, noticing that the star changes in brightness over time. Astronomers established that Betelgeuse has a main period of variability of around 400 days and a more extended secondary period of around six years.
Betelgeuse is one of the brightest stars in the night sky, and the closest red supergiant to Earth. Credit: IAU and Sky & Telescope
In 2019 and 2020, there was a steep decrease in Betelgeuse’s brightness — an event referred to as the ‘Great Dimming.’ The event led some to believe that a supernova death was quickly approaching, but scientists were able to determine the dimming was actually caused by a large cloud of dust ejected from Betelgeuse.
The Great Dimming mystery was solved, but the event sparked a renewed interest in studying Betelgeuse, which brought about new analyses of archival data on the star. One analysis led scientists to propose that the cause of Betelgeuse’s six-year variability is the presence of a companion star [1]. But when the Hubble Space Telescope and the Chandra X-Ray Observatory searched for this companion, no detections were made.
The companion star has now been detected for the first time by a team of astrophysicists led by Steve Howell, a senior research scientist at NASA Ames Research Center. They observed Betelgeuse using a speckle imager called ‘Alopeke. ‘Alopeke, which means ‘fox’ in Hawaiian, is funded by the NASA–NSF Exoplanet Observational Research Program (NN-EXPLORE) and is mounted on the Gemini North telescope, one half of the International Gemini Observatory, funded in part by the U.S. National Science Foundation and operated by NSF NOIRLab.
Speckle imaging is an astronomical imaging technique that uses very short exposure times to freeze out the distortions in images caused by Earth’s atmosphere. This technique enables high resolution, which, when combined with the light collecting power of Gemini North’s 8.1-meter mirror, allowed for Betelgeuse’s faint companion to be directly detected.
Analysis of the companion star’s light allowed Howell and his team to determine the companion star’s characteristics. They found that it is six magnitudes fainter than Betelgeuse in the optical wavelength range, it has an estimated mass of around 1.5 times that of the Sun, and it appears to be an A- or B-type pre-main-sequence star — a hot, young, blue-white star that has not yet initiated hydrogen burning in its core.
Gemini North Discovers Long-Predicted Stellar Companion of Betelgeuse. Using the NASA-NSF-funded ‘Alopeke instrument on the Gemini North telescope, one half of the International Gemini Observatory, partly funded by the U.S. National Science Foundation (NSF) and operated by NSF NOIRLab, astronomers have discovered a companion star in an incredibly tight orbit around Betelgeuse. This discovery answers the millennia-old question of why this famous star experiences a roughly six-year-long periodic change in its brightness, and provides insight into the physical mechanisms behind other variable red supergiants. The companion star appears blue here because, based on the team’s analysis, it is likely an A- or B-type star, both of which are blue-white due to their high temperatures. ‘Alopeke is funded by the NASA-NSF Exoplanet Observational Research Program (NN-EXPLORE). Credit: International Gemini Observatory/NOIRLab/NSF/AURA Image Processing: M. Zamani (NSF NOIRLab)
The companion is at a relatively close distance away from the surface of Betelgeuse — about four times the distance between the Earth and the Sun. This discovery is the first time a close-in stellar companion has been detected orbiting a supergiant star. Even more impressive — the companion orbits well within Betelgeuse’s outer extended atmosphere, proving the incredible resolving abilities of ‘Alopeke.
“Gemini North’s ability to obtain high angular resolutions and sharp contrasts allowed the companion of Betelgeuse to be directly detected,” says Howell. Furthermore, he explains that ‘Alopeke did what no other telescope has done before: “Papers that predicted Betelgeuse’s companion believed that no one would likely ever be able to image it.”
This discovery provides a clearer picture of this red supergiant’s life and future death. Betelgeuse and its companion star were likely born at the same time. However, the companion star will have a shortened lifespan as strong tidal forces will cause it to spiral into Betelgeuse and meet its demise, which scientists estimate will occur within the next 10,000 years.
Photo of the constellation Orion produced by NOIRLab in collaboration with Eckhard Slawik, a German astrophotographer. Credit: E. Slawik/NOIRLab/NSF/AURA/M. Zamani
The discovery also helps to explain why similar red supergiant stars might undergo periodic changes in their brightness on the scale of many years. Howell shares his hope for further studies in this area:
“This detection was at the very extremes of what can be accomplished with Gemini in terms of high-angular resolution imaging, and it worked. This now opens the door for other observational pursuits of a similar nature.”
Martin Still, NSF program director for the International Gemini Observatory adds: “The speckle capabilities provided by the International Gemini Observatory continue to be a spectacular tool, open to all astronomers for a wide range of astronomy applications. Delivering the solution to the Betelgeuse problem that has stood for hundreds of years will stand as an evocative highlight achievement.”
Gemini North Discovers Long-Predicted Stellar Companion of Betelgeuse. Using the NASA-NSF-funded ‘Alopeke instrument on the Gemini North telescope, one half of the International Gemini Observatory, partly funded by the U.S. National Science Foundation (NSF) and operated by NSF NOIRLab, astronomers have discovered a companion star in an incredibly tight orbit around Betelgeuse. This discovery answers the millennia-old question of why this famous star experiences a roughly six-year-long periodic change in its brightness, and provides insight into the physical mechanisms behind other variable red supergiants. The companion star appears blue here because, based on the team’s analysis, it is likely an A- or B-type star, both of which are blue-white due to their high temperatures. ‘Alopeke is funded by the NASA-NSF Exoplanet Observational Research Program (NN-EXPLORE). Credit: International Gemini Observatory/NOIRLab/NSF/AURA Image Processing: M. Zamani (NSF NOIRLab)
Another opportunity to study Betelgeuse’s stellar companion will occur in November 2027 when it returns to its furthest separation from Betelgeuse, and thus easiest to detect. Howell and his team look forward to observations of Betelgeuse before and during this event to better constrain the nature of the companion.
Breathtaking views of astronomical events are a never-ending source of great excitement for the staff at Gemini North, one half of the International Gemini Observatory, supported in part by the U.S. National Science Foundation and operated by NSF NOIRLab. One such example is the lunar eclipse taking place in the distance on the right side of this image, captured in 2019. It is seemingly encased in the dark blue band above the horizon. Lunar eclipses occur when Earth moves between the Sun and the Moon. The Moon, which is only visible by the sunlight reflected off it, is darkened by the Earth’s shadow. An eclipse like this one can be viewed from anywhere on Earth where the Moon is visible, though the extent of the eclipse depends on how aligned the Moon is to Earth’s shadow and one’s viewing location. In 2022, for example, the two lunar eclipses, both total eclipses, were visible from Gemini North in Hawai‘i. Credit: International Gemini Observatory/NOIRLab/NSF/AURA/J. Chu
Notes
[1] Two papers released in 2024 used decades of observations of Betelgeuse from many observers around the world to predict the orbit and location of the companion star (see DOI: 10.3847/1538-4357/ad93c8 and DOI: 10.3847/1538-4357/ad87f4).
More information
This research is presented in a paper titled “Probable Direct Imaging Discovery of the Stellar Companion to Betelgeuse” to appear in The Astrophysical Journal Letters on 24 July. DOI: 10.3847/2041-8213/adeaaf
The team is composed of Steve B. Howell (NASA Ames Research Center), David R. Ciardi (NASA Exoplanet Science Institute-Caltech/IPAC), Catherine A. Clark (NASA Exoplanet Science Institute-Caltech/IPAC), Douglas A. Hope (Georgia Tech Research Institute, Georgia State University), Colin Littlefield (NASA Ames Research Center, Bay Area Environmental Research Institute), Elise Furlan (NASA Exoplanet Science Institute-Caltech/IPAC).
NSF NOIRLab, the U.S. National Science Foundation center for ground-based optical-infrared astronomy, operates the International Gemini Observatory (a facility of NSF, NRC–Canada, ANID–Chile, MCTIC–Brazil, MINCyT–Argentina, and KASI–Republic of Korea), NSF Kitt Peak National Observatory (KPNO), NSF Cerro Tololo Inter-American Observatory (CTIO), the Community Science and Data Center (CSDC), and NSF–DOE Vera C. Rubin Observatory (in cooperation with DOE’s SLAC National Accelerator Laboratory). It is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with NSF and is headquartered in Tucson, Arizona.
The scientific community is honored to have the opportunity to conduct astronomical research on I’oligam Du’ag (Kitt Peak) in Arizona, on Maunakea in Hawai‘i, and on Cerro Tololo and Cerro Pachón in Chile. We recognize and acknowledge the very significant cultural role and reverence of I’oligam Du’ag to the Tohono O’odham Nation, and Maunakea to the Kanaka Maoli (Native Hawaiians) community.
The NASA–NSF Exoplanet Observational Research Program (NN-EXPLORE) is a joint initiative to advance U.S. exoplanet science by providing the community with access to cutting-edge, ground-based observational facilities. Managed by NASA’s Exoplanet Exploration Program (ExEP), NN-EXPLORE supports and enhances the scientific return of space missions such as Kepler, TESS, HST, and JWST by enabling essential follow-up observations from the ground—creating strong synergies between space-based discoveries and ground-based characterization. ExEP is located at the Jet Propulsion Laboratory. More information at https://exoplanets.nasa.gov/exep/NNExplore/overview/.
GW231123: LIGO-Virgo-KAGRA detect most massive black hole merger to date
Gravitational waves from massive black holes challenge current astrophysical models
The LIGO-Virgo-KAGRA (LVK) Collaboration has detected the merger of the most massive black holes ever observed with gravitational waves using the US National Science Foundation (NSF)-funded LIGO observatories. The powerful merger produced a final black hole approximately 225 times the mass of our Sun. The signal, designated GW231123, was detected during the fourth observing run of the LVK network on November 23, 2023.
The two black holes that merged were approximately 103 and 137 times the mass of the Sun. In addition to their high masses they are also rapidly spinning, making this a uniquely challenging signal to interpret and suggesting the possibility of a complex formation history.
“The discovery of such a massive and highly spinning system presents a challenge not only to our data analysis techniques – says Ed Porter, researcher at the Astroparticle and Cosmology laboratory (APC) of CNRS in Paris – but will have a major effect on the theoretical studies of black hole formation channels and waveform modelling for many years to come. Actually, current models of stellar evolution do not allow the existence of such massive black holes, which could possibly have formed through previous mergers of smaller black holes.”
Approximately 100 black-hole mergers have previously been observed through gravitational waves, analysed and shared with the wider scientific community. Until now the most massive binary was the source of GW190521, with a much smaller total mass of “only” 140 times that of the sun.
Before now, the most massive black hole merger—produced by an event that took place in 2021 called GW190521—had a total mass of 140 times that of the Sun.
In the more recent GW231123 event, the 225-solar-mass black hole was created by the coalescence of black holes each approximately 100 and 140 times the mass of the Sun.
In addition to their high masses, the black holes are also rapidly spinning.
“This is the most massive black hole binary we’ve observed through gravitational waves, and it presents a real challenge to our understanding of black hole formation,” says Mark Hannam of Cardiff University and a member of the LVK Collaboration. “Black holes this massive are forbidden through standard stellar evolution models. One possibility is that the two black holes in this binary formed through earlier mergers of smaller black holes.”
Dave Reitze, the executive director of LIGO at Caltech, says, “This observation once again demonstrates how gravitational waves are uniquely revealing the fundamental and exotic nature of black holes throughout the universe.”
A record-breaking system
The high mass and extremely rapid spinning of the black holes in GW231123 push the limits of both gravitational-wave detection technology and current theoretical models. Extracting accurate information from the signal required the use of models that account for the intricate dynamics of highly spinning black holes.
“The black holes appear to be spinning very rapidly—near the limit allowed by Einstein’s theory of general relativity,” explains Charlie Hoy of the University of Portsmouth and a member of the LVK. “That makes the signal difficult to model and interpret. It’s an excellent case study for pushing forward the development of our theoretical tools.”
Researchers are continuing to refine their analysis and improve the models used to interpret such extreme events. “It will take years for the community to fully unravel this intricate signal pattern and all its implications,” says Gregorio Carullo of the University of Birmingham and a member of the LVK. “Despite the most likely explanation remaining a black hole merger, more complex scenarios could be the key to deciphering its unexpected features. Exciting times ahead!”
Probing the limits of gravitational-wave astronomy
The high mass and extremely rapid spinning of the black holes in GW231123 pushes the limits of both gravitational-wave detection technology and current theoretical models. Extracting accurate information from the signal required the use of theoretical models that account for the complex dynamics of highly spinning black holes.
“This event pushes our instrumentation and data-analysis capabilities to the edge of what’s currently possible,” says Dr. Sophie Bini, a postdoctoral researcher at Caltech, previously at the University of Trento. “It’s a powerful example of how much we can learn from gravitational-wave astronomy—and how much more there is to uncover.”
Gravitational-wave detectors such as LIGO in the United States, Virgo in Italy, and KAGRA in Japan are designed to measure minute distortions in spacetime caused by violent cosmic events like black hole mergers. The fourth observing run began in May 2023 and observations from the first half of the run (up to January 2024) will be published later in the summer.
“With the longest continuous observation to date and enhanced sensitivity, the LIGO-Virgo-KAGRA fourth observing campaign is delivering invaluable new insights into our understanding of the universe –says Viola Sordini, researcher at the Institute of Physics of the 2 Infinities (IP2I) of CNRS in Lyon and deputy spokesperson of the Virgo Collaboration – This exciting discovery opens a new season of results, with many more expected throughout the summer and a continued stream of findings anticipated over the next two years. Publications are followed by release of the data, in support of the broader scientific community and open science”
GW231123 will be presented at the 24th International Conference on General Relativity and Gravitation (GR24) and the 16th Edoardo Amaldi Conference on Gravitational Waves, held jointly as the GR-Amaldi meeting in Glasgow, UK, from July 14-18 2025.
LIGO, the Laser Interferometer Gravitational-wave Observatory, made history in 2015 when it made the first-ever direct detection of gravitational waves, ripples in space-time. In that case, the waves emanated from a black hole merger that resulted in a final black hole 62 times the mass of our Sun. The signal was detected jointly by the twin detectors of LIGO, one located in Livingston, Louisiana, and the other in Hanford, Washington.
Since then, the LIGO team has teamed up with partners at the Virgo detector in Italy and KAGRA (Kamioka Gravitational Wave Detector) in Japan to form the LVK Collaboration. These detectors have collectively observed more than 200 black hole mergers in their fourth run, and about 300 in total since the start of the first run in 2015.
The LIGO-Virgo-KAGRA Collaboration
LIGO is funded by the NSF, and operated by Caltech and MIT, which conceived and built the project. Financial support for the Advanced LIGO project was led by NSF with Germany (Max Planck Society), the U.K. (Science and Technology Facilities Council) and Australia (Australian Research Council) making significant commitments and contributions to the project. More than 1,600 scientists from around the world participate in the eQort through the LIGO Scientific Collaboration, which includes the GEO Collaboration. Additional partners are listed at https://my.ligo.org/census.php.
The Virgo Collaboration is currently composed of approximately 1.000 members from 175 institutions in 20 different (mainly European) countries. The European Gravitational Observatory (EGO) hosts the Virgo detector near Pisa in Italy, and is funded by Centre National de la Recherche Scientifique (CNRS) in France, the National Institute of Nuclear Physics (INFN) in Italy, the National Institute of Subatomic Physics (Nikhef) in the Netherlands, The Research Foundation – Flanders (FWO) e the Belgian Fund for Scientific Research (F.R.S.–FNRS). A list of the Virgo Collaboration groups can be found at: https://www.virgo-gw.eu/about/scientific-collaboration/. More information is available on the Virgo website at https://www.virgo-gw.eu.
KAGRA is the laser interferometer with 3 km arm-length in Kamioka, Gifu, Japan. The host institute is Institute for Cosmic Ray Research (ICRR), the University of Tokyo, and the project is co-hosted by National Astronomical Observatory of Japan (NAOJ) and High Energy Accelerator Research Organization (KEK). KAGRA collaboration is composed of over 400 members from 128 institutes in 17 countries/regions. KAGRA’s information for general audiences is at the website https://gwcenter.icrr.u-tokyo.ac.jp/en/. Resources for researchers are accessible from http://gwwiki.icrr.u-tokyo.ac.jp/JGWwiki/KAGRA.
Press release from EGO and California Institute of Technology
