SPACE/COSMOS
Signs of alien life may be hiding in these gases
Advancing the search for weird life on weird planets
image:
Artist's illustration of a potential Hycean world, where methyl halide gases would be detectable in the atmosphere.
view moreCredit: NASA, ESA, CSA, Joseph Olmsted/STScI
Scientists have identified a promising new way to detect life on faraway planets, hinging on worlds that look nothing like Earth and gases rarely considered in the search for extraterrestrials.
In a new Astrophysical Journal Letters paper, researchers from the University of California, Riverside, describe these gases, which could be detected in the atmospheres of exoplanets — planets outside our solar system — with the James Webb Space Telescope, or JWST.
Called methyl halides, the gases comprise a methyl group, which bears a carbon and three hydrogen atoms, attached to a halogen atom such as chlorine or bromine. They’re primarily produced on Earth by bacteria, marine algae, fungi, and some plants.
One key aspect of searching for methyl halides is that exoplanets resembling Earth are too small and dim to be seen with JWST, the largest telescope currently in space.
Instead, JWST would have to aim for larger exoplanets orbiting small red stars, with deep global oceans and thick hydrogen atmospheres called Hycean planets. Humans could not breathe or survive on these worlds, but certain microbes might thrive in such environments.
“Unlike an Earth-like planet, where atmospheric noise and telescope limitations make it difficult to detect biosignatures, Hycean planets offer a much clearer signal,” said Eddie Schwieterman, UCR astrobiologist and paper co-author.
The researchers believe that looking for methyl halides on Hycean worlds is an optimal strategy for the present moment in time.
“Oxygen is currently difficult or impossible to detect on an Earth-like planet. However, methyl halides on Hycean worlds offer a unique opportunity for detection with existing technology,” said Michaela Leung, UCR planetary scientist and first author of the paper.
Additionally, finding these gases could be easier than looking for other types of biosignature gases indicative of life.
“One of the great benefits of looking for methyl halides is you could potentially find them in as few as 13 hours with James Webb. That is similar or lower, by a lot, to how much telescope time you’d need to find gases like oxygen or methane,” Leung said. “Less time with the telescope means it’s less expensive.”
Though life forms do produce methyl halides on Earth, the gas is found in low concentrations in our atmosphere. Because Hycean planets have such a different atmospheric makeup and are orbiting a different kind of star, the gases could accumulate in their atmospheres and be detectable from light-years away.
“These microbes, if we found them, would be anaerobic. They’d be adapted to a very different type of environment, and we can’t really conceive of what that looks like, except to say that these gases are a plausible output from their metabolism,” Schwieterman said.
The study builds on previous research investigating different biosignature gases, including dimethyl sulfide, another potential sign of life. However, methyl halides appear particularly promising because of their strong absorption features in infrared light as well as their potential for high accumulation in a hydrogen-dominated atmosphere.
While James Webb is currently the best tool for this search, future telescopes, like the proposed European LIFE mission, could make detecting these gases even easier. If LIFE launches in the 2040s as proposed, it could confirm the presence of these biosignatures in less than a day.
“If we start finding methyl halides on multiple planets, it would suggest that microbial life is common across the universe,” Leung said. “That would reshape our understanding of life’s distribution and the processes that lead to the origins of life.”
Moving forward, the researchers plan to expand this work on other planetary types and other gases. For example, they’ve done measurements of gases emanating from the Salton Sea, which appears to produce halogenated gases, such as chloroform. “We want to get measurements of other things produced in extreme environments on Earth, which could be more common elsewhere,” Schwieterman said.
Even as researchers push the boundaries of detection, they acknowledge that direct sampling of exoplanet atmospheres remains beyond current capabilities. However, advances in telescope technology and exoplanet research could one day bring us closer to answering one of humanity’s biggest questions: Are we alone?
“Humans are not going to visit an exoplanet anytime soon,” Schwieterman said. “But knowing where to look, and what to look for, could be the first step in finding life beyond Earth.”
Journal
The Astrophysical Journal Letters
Article Title
Examining the Potential for Methyl Halide Accumulation and Detectability in Possible Hycean-type Atmospheres
Article Publication Date
11-Mar-2025
Entwined dwarf stars reveal their location thanks to repeated radio bursts
We now know it isn’t just neutron stars that emit such pulses
image:
Artist's impression of a red dwarf (left) and a white dwarf orbiting each other, emitting radio pulses.
view moreCredit: Credit: Daniëlle Futselaar/artsource.nl
An international team of astronomers led by Dr Iris de Ruiter, now at the University of Sydney, has shown that a white dwarf and a red dwarf star orbiting each other every two hours are emitting radio pulses.
Thanks to follow-up observations using optical and x-ray telescopes, the researchers were able to determine the origin of these pulses with certainty. The findings explain the source of such radio emissions found across the Milky Way galaxy for the first time.
The results are published in Nature Astronomy.
In recent years, better analysis techniques have given researchers the ability to detect radio pulses that last from seconds to minutes and seem to come from stars in the Milky Way. There have been many hypotheses about what triggers these pulses, but until now there has been no hard evidence as to their source. This study led by Dr de Ruiter while at the University of Amsterdam changes this.
Dr de Ruiter, who received her doctorate from the University of Amsterdam in October 2024, is now a postdoctoral researcher at the University of Sydney. During the last year of her PhD, she developed a method to search for radio pulses of seconds to minutes in the historical archive of LOFAR, the Low-Frequency Array telescope in the Netherlands.
While improving the method, Dr de Ruiter discovered a single pulse in the 2015 observations. When she subsequently sifted through more archive data from the same patch of sky, she discovered six more pulses. All the pulses came from a source called ILTJ1101.
Red and white dwarf
Follow-up observations with the 6.5m Multiple Mirror Telescope in Arizona and the Hobby-Eberly Telescope in Texas (USA) showed that it is not one flashing star, but two stars that together cause the pulse. The two stars, a red dwarf and a white dwarf, orbit a common centre of gravity every 125 minutes. They are located about 1600 light-years from us in the direction of the Big Dipper, also known as the Plough, within the Ursa Major constellation.
Astronomers believe that the radio emission is caused by the interaction of the red dwarf with the white dwarf's magnetic field.
Astronomers plan to study the ultraviolet emission of these entwined stars in detail. This will help to determine the temperature of the white dwarf and learn more about the history of white and red dwarfs.
"It was especially cool to add new pieces to the puzzle," Dr de Ruiter said. "We worked with experts from all kinds of astronomical disciplines. With different techniques and observations, we got a little closer to the solution step by step".
Neutron star monopoly broken
Because of this discovery, astronomers now know that neutron stars do not have the monopoly on bright radio pulses. In recent years, about 10 such radio-emitting systems have been discovered by other research groups. However, these groups have not yet been able to prove whether these pulses come from a white dwarf or a neutron star.
Researchers are now searching through the LOFAR data to find more such long-period pulses. Co-author Dr Kaustubh Rajwade (University of Oxford, UK) said: “There are probably many more of these types of radio pulses hidden in the LOFAR archive, and each discovery teaches us something new.”
-ENDS-
Interviews
Dr Iris de Ruiter | iris.deruiter@sydney.edu.au
Media enquiries
Marcus Strom | marcus.strom@sydney.edu.au | +61 474 269 459
Outside of work hours: please call +61 2 8627 0246 (directs to a mobile number) or email media.office@sydney.edu.au.
Research: Iris de Ruiter, et al, ‘A white dwarf binary showing sporadic radio pulses at the orbital period’ (Nature Astronomy 2025) DOI: 10.1038/s41550-025-02491-0
Download photos of Dr de Ruiter and the illustration at this link.
Declaration: The authors declare no competing interests. Research was funded by the Dutch Research Council, University of Amsterdam, ASTRON, European Research Council and the Australian Research Council Centre of Excellence for Gravitational Wave Discovery (OzGrav). A full list of funding available in the paper.
Journal
Nature Astronomy
Method of Research
Observational study
Subject of Research
Not applicable
Article Title
A white dwarf binary showing sporadic radio pulses at the orbital period
Article Publication Date
12-Mar-2025
First radio pulses traced to dead-star binary
White dwarf and red dwarf bump together to emit a radio blast every two hours
Northwestern University
image:
Artist's impression of a red dwarf (left) and a white dwarf (center) orbiting each other. The stars’ orbit is so tight that their magnetic fields interact, causing pulses of radio emission every two hours.
view moreCredit: Daniëlle Futselaar/artsource.nl
An international team of astronomers, including a Northwestern University astrophysicist, has traced a series of mysterious radio pulses to an unprecedented home.
Starting a decade ago, astronomers have detected a pulse of radio emission every two hours, coming from the direction of the Big Dipper. After combining observations from multiple telescopes, the team can now reveal the culprit: a binary system with a dead star.
According to the new study, a red dwarf and white dwarf are orbiting each other so tightly that their magnetic fields interact. Each time they bump together — which is every two hours — the interaction emits a long radio blast.
Although astronomers previously only traced long radio pulses to neutron stars, the new discovery shows the movement of stars within a binary system also can emit long-period radio bursts.
The study will be published on Wednesday (March 12) in the journal Nature Astronomy.
“There are several highly magnetized neutron stars, or magnetars, that are known to exhibit radio pulses with a period of a few seconds,” said Northwestern astrophysicist and study coauthor Charles Kilpatrick. “Some astrophysicists also have argued that sources might emit pulses at regular time intervals because they are spinning, so we only see the radio emission when source is rotated toward us. Now, we know at least some long-period radio transients come from binaries. We hope this motivates radio astronomers to localize new classes of sources that might arise from neutron star or magnetar binaries.”
Kilpatrick is a research assistant professor at Northwestern’s Center for Interdisciplinary Exploration and Research in Astrophysics. Iris de Ruiter, a postdoctoral scholar at the University of Sydney in Australia, led the study. At the time of the research, she was a Ph.D. student at the University of Amsterdam in the Netherlands.
Repeating radio signals
De Ruiter first discovered the pulses last year as she combed through archives from the Low Frequency Array(LOFAR), the largest radio telescope operating at the lowest frequencies that can be observed from Earth. Looking through the data, she found the first pulse appeared in 2015. When she subsequently sifted through more archival data from the same area of sky, de Ruiter discovered six more pulses.
Like a short flash of light — but in radio form — each pulse lasts anywhere from seconds to minutes in length. And, strangely, the pulses repeat at regular intervals, like a cosmic clock that ticks once every two hours. In recent years, astronomers have discovered more and more fast radio burst (FRBs). The radio pulses in question, however, are a much rarer event.
“The radio pulses are very similar to FRBs, but they each have different lengths,” Kilpatrick said. “The pulses have much lower energies than FRBs and usually last for several seconds, as opposed to FRBs which last milliseconds. There’s still a major question of whether there’s a continuum of objects between long-period radio transients and FRBs, or if they are distinct populations.”
Curious about the pulses’ sources, de Ruiter and her team obtained follow-up observations from the MMT Observatory in Arizona and the McDonald Observatory in Texas. Those observations revealed the source was not one flashing star — but two stars pulsing together. Located just 1,600 lightyears from Earth, the two stars orbit a common center of gravity, making a full revolution every 125.5 minutes.
The dead star dance
To confirm these findings, Kilpatrick used Northwestern’s remote access to the Multiple Mirror Telescope (MMT) in Arizona to observe the system during its full two-hour-long cycle. “Northwestern’s private access to the MMT enabled this science, which would not have been possible otherwise,” he said.
These observations allowed Kilpatrick to track variations in the system’s movement and gain optical spectra from the red dwarf. By taking light emitted from a star and splitting it into its component colors (or spectra), Kilpatrick was able to gain information about the star itself.
“The spectroscopic lines in these data allowed us to determine that the red dwarf is moving back and forth very rapidly with exactly the same two-hour period as the radio pulses,” Kilpatrick said. “That is convincing evidence that the red dwarf is in a binary system.”
The “back-and-forth” motion appeared to be from a companion star’s gravity pulling the red dwarf around. By precisely calculating the variation in these motions, Kilpatrick measured the mass of the much fainter companion. The calculated mass aligned with the typical mass of a white dwarf. While white dwarfs can range from low- to medium-mass, like our sun, red dwarfs are always much smaller and cooler.
“In almost every scenario, its mass and the fact that it is too faint to see means it must be a white dwarf,” Kilpatrick said. “This confirms the leading hypothesis for the white dwarf binary origin and is the first direct evidence we have for the progenitor systems of long-period radio transients.”
In the future, astronomers plan to study the ultraviolet emission of the binary source, dubbed ILTJ1101, in more detail. The findings could help determine the temperature of the white dwarf and reveal more about the history of white and red dwarfs.
“It was especially cool to add new pieces to the puzzle,” de Ruiter said. “We worked with experts from all kinds of astronomical disciplines. With different techniques and observations, we got a little closer to the solution step by step.”
The study, “A white dwarf binary showing sporadic radio pulses at the orbital period,” is based in part on data obtained with the International LOFAR Telescope (ILT), designed and constructed by ASTRON.
Journal
Nature Astronomy
Method of Research
Observational study
Subject of Research
Not applicable
Article Title
Sporadic radio pulses from a white dwarf binary at the orbital period
Article Publication Date
12-Mar-2025
Two-star system explains unusual astrophysical phenomenon
image:
Artistic illustration showing the radio pulses emitted by the binary star system: a white dwarf in orbit around a red dwarf.
view moreCredit: Daniëlle Futselaar/artsource.nl
(Images available via the links in the Notes section) An international team of astrophysicists led by the Netherlands and the UK have discovered that radio pulses lasting seconds to minutes are due to two stars coming together – rather than emissions from a single star. The results are published today (12 March) in Nature Astronomy.
In recent years, a new astronomical phenomenon has puzzled radio astronomers: researchers have detected radio pulses from the Milky Way that last from seconds to minutes. These pulses are unlike anything expected from known radio-emitting neutron stars, or pulsars*, which produce pulses on the order of milliseconds. Furthermore, these so-called long-period transients (LPTs) are periodic at timescales of 10s of minutes to hours, unlike a radio pulsar (that emits radio waves once every few seconds).
There have been a few hypotheses for the origins of these novel pulses, but evidence has been scant. Now, a new discovery led by astronomers from the Netherlands and the UK has provided vital clues to the nature of these radio bursts for the first time.
The study focused on a collection of these mysterious periodic radio signals detected in 2022. Using a novel imaging technique, the team led by Dr Iris de Ruiter (University of Amsterdam at the time of the study, now University of Sydney) with Dr Kaustubh Rajwade (Department of Physics, University of Oxford) detected several of these LPT radio pulses in data taken with the Low Frequency Array (LOFAR), an international radio telescope.
Acting like a large radio camera, the telescope could pinpoint the exact location of the radio pulse in the sky that was traced to a star-like object about 1,600 light-years away. Follow-up observations with the 6.5 m diameter Multiple Mirror Telescope in Arizona and the Hobby-Eberly Telescope in Texas (USA) showed that it is not one flashing star, but two stars that together cause the pulse.
The two stars, a white dwarf (a rather bright ember of a Sun-like star after it sheds away all the material around it) in orbit around a red dwarf (a star much smaller and lighter than the Sun), orbit a common centre of gravity every 125 minutes. The star system is located in the direction of the constellation of the Great Bear (Ursa Major).
According to the researchers, there are two possibilities for how the stars generate the unusually long radio pulses. Potentially, the radio bursts emanate from the strong magnetic field of the white dwarf, or they could be produced by the interaction of the magnetic fields of the white dwarf and its stellar companion. However, further observations are needed to clarify this.
‘Thanks to this discovery, we now know that compact objects other than neutron stars are capable of producing bright radio emission,’ comments Dr Rajwade who leads the effort to find the unexplained LPTs with the LOFAR telescope and helped to identify the periodic pattern between radio pulses.
‘We worked with experts from all kinds of astronomical disciplines,’ adds Dr de Ruiter. ‘With different techniques and observations, we got a little closer to the solution step by step.’
In recent years, about ten such radio-emitting systems have been discovered by other research groups. However, these groups have not yet been able to prove whether these pulses come from a white dwarf or a neutron star.
Dr Rajwade continues to search the data from LOFAR for LPTs: ‘This finding is very exciting! We are starting to find a few of these LPTs in our radio data. Each discovery is telling us something new about the extreme astrophysical objects that can create the radio emission we see. For instance, the unexpected observation of coherent radio emission from the white dwarf in this study could help probe the evolution of magnetic fields in this type of star.’
*Pulsar: stellar remains of a brilliant supernova explosion.
Notes to editors:
For media enquiries, contact Dr Caroline Wood, University of Oxford: caroline.wood@admin.ox.ac.uk
The study 'Sporadic radio pulses from a white dwarf binary at the orbital period’, will be published in Nature Astronomy at 10.00am GMT, Wednesday 12 March 2025 at
https://www.nature.com/articles/s41550-025-02491-0
To view a copy of the manuscript before this, contact Dr Caroline Wood, University of Oxford: caroline.wood@admin.ox.ac.uk
Images related to this study are available © Daniëlle Futselaar/artsource.nl [high resolution 16:9 | high resolution 4:3]
Images are for editorial use ONLY relating to this press release and MUST be credited (see filename). These must NOT be sold on to third parties.
About the University of Oxford:
Oxford University has been placed number 1 in the Times Higher Education World University Rankings for the ninth year running, and number 3 in the QS World Rankings 2024. At the heart of this success are the twin-pillars of our ground-breaking research and innovation and our distinctive educational offer.
Oxford is world-famous for research and teaching excellence and home to some of the most talented people from across the globe. Our work helps the lives of millions, solving real-world problems through a huge network of partnerships and collaborations. The breadth and interdisciplinary nature of our research alongside our personalised approach to teaching sparks imaginative and inventive insights and solutions.
Through its research commercialisation arm, Oxford University Innovation, Oxford is the highest university patent filer in the UK and is ranked first in the UK for university spinouts, having created more than 300 new companies since 1988. Over a third of these companies have been created in the past five years. The university is a catalyst for prosperity in Oxfordshire and the United Kingdom, contributing £15.7 billion to the UK economy in 2018/19, and supports more than 28,000 full time jobs.
Journal
Nature Astronomy
Article Title
Sporadic radio pulses from a white dwarf binary at the orbital period
Article Publication Date
12-Mar-2025
Black holes: not endings, but beginnings? New research could revolutionize our understanding of the universe
image:
Artist impression of a white hole
view moreCredit: University of Sheffield
New research suggests black holes may transition into ‘white holes’, ejecting matter and potentially even time back into the universe, defying our current understanding of these cosmic giants
The study by the University of Sheffield proposes a revolutionary link between time and dark energy, suggesting that the mysterious force driving the universe's expansion may be used to measure time
The research could pave the way for groundbreaking new fundamental theories and breakthroughs in our understanding of the universe
Our understanding of black holes, time and the mysterious dark energy that dominates the universe could be revolutionised, as new University of Sheffield research helps unravel the mysteries of the cosmos.Black holes – areas of space where gravity is so strong that not even light can escape – have long been objects of fascination, with astrophysicists, theoretical physicists and others dedicating their lives to revealing their secrets. This fascination with the unknown has inspired numerous writers and filmmakers, with novels and films such as 2001: A Space Odyssey, The Martian and Interstellar exploring these enigmatic objects' hold on our collective imagination.
According to Einstein’s Theory of General Relativity, anyone trapped inside a black hole would fall towards its centre and be destroyed by immense gravitational forces. This centre, known as a singularity, is the point where the matter of a giant star, which is believed to have collapsed to form the black hole, is crushed down into an infinitesimally tiny point. At this singularity, our understanding of physics and time breaks down.
Using the laws of quantum mechanics, a fundamental theory describing the nature of the universe at the level of atoms and even smaller particles, the new study proposes a radically different theoretical standpoint where, rather than a singularity signifying the end, it could represent a new beginning.
The new paper entitled ‘Black Hole Singularity Resolution in Unimodular Gravity from Unitarity’, published today in the scientific journal Physical Review Letters, aims to illustrate the point where our current grasp of physics and time falters.
While black holes are often described as sucking everything, including time, into a point of nothingness, in the paper, white holes are theorised to act in reverse, ejecting matter, energy and time back into the universe.
The study uses a simplified, theoretical model of a black hole, known as a planar black hole. Unlike typical black holes, which have a spherical shape, a planar black hole's boundary is a flat, two-dimensional surface. The researchers’ ongoing work suggests that the same mechanism could also apply to a typical black hole.
“It has long been a question as to whether quantum mechanics can change our understanding of black holes and give us insights into their true nature,” said Dr Steffen Gielen, from the University of Sheffield’s School of Mathematical and Physical Sciences, who co-wrote the paper with Lucía Menéndez-Pidal from Complutense University of Madrid.
“In quantum mechanics, time as we understand it cannot end as systems perpetually change and evolve.”
The scientists’ findings demonstrate how, using the laws of quantum mechanics, the black hole singularity is replaced by a region of large quantum fluctuations - tiny, temporary changes in the energy of space - where space and time do not end. Instead, space and time transition into a new phase called a white hole - a theoretical region of space thought to function in the opposite way to a black hole. As such, a white hole could be where time begins.
“While time is, in general, thought to be relative to the observer, in our research time is derived from the mysterious dark energy which permeates the entire universe,” Dr Gielen continued.
“We propose that time is measured by the dark energy that is everywhere in the Universe, and responsible for its current expansion.This is the pivotal new idea that allows us to grasp the phenomena occurring within a black hole.”
Dark energy is a mysterious, theoretical force that scientists believe drives the accelerating expansion of the universe. The new study uses dark energy almost as a point of reference, with energy and time as complementary ideas that can be measured against one another.
Tantalisingly, the theory that what we perceive as a singularity is actually a beginning suggests the existence of something even more enigmatic on the other side of a white hole.
“Hypothetically you could have an observer - a hypothetical entity - go through the black hole, through what we think of as a singularity and emerge on the other side of the white hole. It’s a highly abstract notion of an observer but it could happen, in theory,” Dr Gielen added.
Beyond such theoretical musings, the suggestion of a profound connection between the nature of time at the most fundamental level and the mysterious dark energy that governs the cosmos will be explored further in the months and years ahead.
The new research also suggests novel approaches to reconciling gravity and quantum mechanics, potentially paving the way for groundbreaking new fundamental theories and breakthroughs in our understanding of the universe.
You can read the paper in full here.
The University of Sheffield
The University of Sheffield is a leading Russell Group university, with a world-class reputation, ranked within the Top 100 universities in the world (Times Higher Education World University Rankings 2025). Over 30,000 students from 150 countries study at Sheffield and in a truly global community, they learn alongside over 1,500 of the world’s leading academics.
Sheffield’s world-shaping research feeds into its excellent education. Students learn at the leading edge of discovery from researchers who are tackling today’s biggest global challenges.
Driven by outstanding people, staff and students share a commitment to changing the world for the better, through the power and application of ideas and knowledge.
From the first documented use of penicillin as a therapy in 1930, to building Europe’s largest research-led manufacturing cluster, Sheffield’s inventive spirit and top quality research environment sets it apart.
Current research partners include Boeing, Rolls-Royce, Unilever, AstraZeneca, GlaxoSmithKline, Siemens and Airbus, as well as many government agencies and charitable foundations.
Sheffield was voted University of the Year in 2024 at the Whatuni Student Choice Awards - the largest annual university awards in the UK voted for exclusively by students. The award reflects a commitment to world-class education and an outstanding student experience. Its Students' Union, which is home to more than 350 societies and clubs, was also named Best Students’ Union for the seventh consecutive year.
Over 300,000 Sheffield alumni from 205 different countries make a significant influence across the world, with six Nobel Prize winners included amongst former staff and students.
To find out more, visit: www.sheffield.ac.uk
Journal
Physical Review Letters
Method of Research
Observational study
Subject of Research
Not applicable
Article Title
Black Hole Singularity Resolution in Unimodular Gravity from Unitarity
Article Publication Date
12-Mar-2025
SwRI-led PUNCH constellation launches
NASA satellites poised to image how the solar corona transitions into the solar wind
image:
Prior to launch, the PUNCH spacecraft were attached to the gold-colored ESPA ring designed to deploy secondary payloads, below NASA’s SPHEREx observatory, to cost-effectively share a ride to space. PUNCH’s four small suitcase-sized spacecraft, designed and built by Southwest Research Institute, will revolutionize our understanding of how the solar corona, the Sun’s outer atmosphere, becomes the solar wind that fills and defines our heliosphere.
view moreCredit: BAE Systems/Benjamin Fry
SAN ANTONIO — March 12, 2025 — Four small suitcase-sized spacecraft, designed and built by Southwest Research Institute headquartered in San Antonio, launched from Vandenberg Space Force Base in California on March 11. NASA’s Polarimeter to Unify the Corona and Heliosphere, or PUNCH, constellation has spread out in a low-Earth orbit along the day-night line, providing a clear view in all directions for its two-year primary mission.
“The PUNCH spacecraft are now drifting into perfect position to study the solar corona, the Sun’s outer atmosphere, as it transitions into the solar wind that fills our solar system,” said PUNCH Principal Investigator Dr. Craig DeForest of SwRI’s Solar System Science and Exploration Division located in Boulder, Colo. “To get the data we need, we had to create an instrument as large as the Earth. Because that wasn’t possible, we used four small spacecraft, synchronized and spread around the entire planet, to create a virtual instrument 8,000 miles across. That lets us look up to 45° from the Sun in all directions, all the time.”
One satellite carries a coronagraph, the Narrow Field Imager developed by the U.S. Naval Research Laboratory, that images the Sun’s corona continuously. The other three carry SwRI-developed Wide Field Imagers, designed to view the very faint outermost portion of the solar corona and the solar wind itself. PUNCH will also track space weather events, such as coronal mass ejections traveling across the solar system, in three dimensions for the first time.
“PUNCH will make the invisible visible,” DeForest said. “Deep baffles in our wide-field imagers reduce direct sunlight by over 16 orders of magnitude or a factor of 10 million billion — the ratio between the mass of a human and the mass of a cold virus. Then state-of-the-art processing on the ground removes the background starfield, over 99% of the light in each image, to reveal the extremely faint glimmer of the solar wind.”
The spacecraft have started a 90 day-commissioning period from the Mission Operations Center, located at SwRI’s Boulder, Colo., offices. In June 2025, the science mission begins, and the Science Operations Center will begin sharing data with the rest of the world, via NASA’s Solar Data Analysis Center.
Each spacecraft includes a camera, developed by RAL Space in the United Kingdom, to collect three raw images, through three different polarizing filters, every four minutes. In addition, each spacecraft will produce a clear unpolarized image every eight minutes, for calibration. These images will allow scientists to discern the exact trajectory and speed of coronal mass ejections as they move through the inner solar system, improving on current instruments that only measure the corona itself and also do not routinely exploit the polarization of light.
“While PUNCH is a research mission, we will be able to track space storms, or coronal mass ejections, in three dimensions as they approach the Earth — this is critical to forecasting space weather and how it might affect us as a space-faring society,” DeForest said. “We hope PUNCH will help revolutionize space weather forecasting in the same way that geosynchronous satellites revolutionized weather forecasting on Earth.”
PUNCH shared a ride to space with NASA’s Spectro-Photometer for the History of the Universe, Epoch of Reionization and Ices Explorer (SPHEREx) observatory. NASA’s Small Explorers (SMEX) program provides frequent flight opportunities for world-class scientific investigations from space using innovative, efficient approaches within the heliophysics and astrophysics science areas. In addition to leading the PUNCH science mission, SwRI will operate the four spacecraft. The PUNCH team includes the U.S. Naval Research Laboratory, which built the Narrow Field Imager, and RAL Space in Oxfordshire, United Kingdom, which provided detector systems for the four visible-light cameras.
To view a video about the mission, see: https://youtu.be/3BL18jyKeOI
For more information, visit https://www.swri.org/markets/earth-space/space-research-technology/space-science/heliophysics.
Four small suitcase-sized spacecraft, designed and built by Southwest Research Institute headquartered in San Antonio, launched from Vandenberg Space Force Base in California on March 11. NASA’s Polarimeter to Unify the Corona and Heliosphere, or PUNCH, constellation has deployed. When it reaches final configuration in low Earth orbit, it will provide a clear view in all directions for its two-year primary mission.
Credit
SpaceX
Planetary system found around nearest single star
Gemini North’s MAROON-X instrument finds evidence for four mini-Earth exoplanets around our famous cosmic neighbor Barnard’s Star
Association of Universities for Research in Astronomy (AURA)
image:
For a century, astronomers have been studying Barnard’s Star in the hope of finding planets around it. First discovered by E. E. Barnard at Yerkes Observatory in 1916, it is the nearest single star system to Earth. Now, using in part the Gemini North telescope, one half of the International Gemini Observatory, partly funded by the U.S. National Science Foundation and operated by NSF NOIRLab, astronomers have discovered four sub-Earth exoplanets orbiting the star. One of the planets is the least massive exoplanet ever discovered using the radial velocity technique, indicating a new benchmark for discovering smaller planets around nearby stars.
view moreCredit: International Gemini Observatory/NOIRLab/NSF/AURA/P. Marenfeld
For a century, astronomers have been studying Barnard’s Star in the hope of finding planets around it. First discovered by E. E. Barnard at Yerkes Observatory in 1916, it is the nearest single star system to Earth [1]. Barnard’s Star is classified as a red dwarf — low-mass stars that often host closely-packed planetary systems, often with multiple rocky planets. Red dwarfs are extremely numerous in the Universe, so scientists are interested in understanding the environments of the planets they host.
One such effort was led by Jacob Bean from the University of Chicago, whose team created an instrument called MAROON-X, which is designed specifically to search for distant planets around red dwarf stars. MAROON-X 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.
MAROON-X hunts for exoplanets using the radial velocity technique, meaning it detects the subtle back and forth wobble of a star as its exoplanets gravitationally tug on it, which causes the light emitted by the star to shift ever so slightly in wavelength. The powerful instrument measures these small shifts in light so precisely that it can even tease apart the number and masses of the planets that must be circling the star to have the observed effect.
After rigorously calibrating and analyzing data taken during 112 nights over a period of three years, the team found solid evidence for three exoplanets around Barnard’s Star, two of which were previously classified as candidates. The team also combined data from MAROON-X with data from a 2024 study done with the ESPRESSO instrument at the European Southern Observatory’s Very Large Telescope in Chile to confirm the existence of a fourth planet, elevating it as well from candidate to bona fide exoplanet.
“It’s a really exciting find — Barnard’s Star is our cosmic neighbor, and yet we know so little about it,” says Ritvik Basant, PhD student at the University of Chicago and first author of the paper appearing in The Astrophysical Journal Letters. “It’s signaling a breakthrough with the precision of these new instruments from previous generations.”
The newly discovered planets are most likely rocky planets, rather than gas planets like Jupiter. However, this will be difficult to pin down with certainty since, because of the angle we observe them from Earth, the planets do not cross in front of their star, which is the usual method for determining a planet’s composition. But with information from similar planets around other stars, the team will be able to make better estimates of their makeup.
They were, however, able to rule out with a fair degree of certainty the existence of other exoplanets with masses comparable to Earth in Barnard Star’s habitable zone — the region of space around a star that is just right to allow liquid water on an orbiting planet’s surface.
Barnard’s Star has been called the “great white whale” for planet hunters; several times over the past century, groups have announced evidence that suggested planets around Barnard’s Star, only for them to be subsequently disproved. But these latest findings give a much larger degree of confidence than any previous result.
“We observed at different times of night on different days. They’re in Chile; we’re in Hawai‘i. Our teams didn’t coordinate with each other at all,” says Basant. “That gives us a lot of assurance that these aren’t phantoms in the data.”
The four planets, each only about 20 to 30% the mass of Earth, are so close to their home star that they zip all the way around it in a matter of days. The fourth planet is the least massive planet discovered to date using the radial velocity technique. The team hopes this will spark a new era of finding more and more sub-Earth exoplanets in the Universe.
Most rocky planets found so far are much larger than Earth, and they appear to be fairly similar throughout the Milky Way Galaxy. But there are reasons to think that smaller exoplanets have more widely varied compositions. As scientists find more of them, they can begin to tease out more information about how these planets form and what makes them likely to have habitable conditions.
“The U.S. National Science Foundation is collaborating with the astronomy community on an adventure to look deeper into the Universe to detect planets with environments that might resemble Earth's,” says Martin Still, NSF program director for the International Gemini Observatory. “The planet discoveries provided by MAROON-X mounted on Gemini North provide a significant step along that journey.”
MAROON-X is still a visiting instrument at Gemini North. Given its outstanding performance and popularity with the user community, it is in the process of being converted to a permanent facility instrument.
“This result demonstrates the competitive, state-of-the-art capabilities that Gemini offers its user community. The observatory is in the middle of rejuvenating its instrumentation portfolio and MAROON-X is part of the first wave of new instruments, alongside GHOST on Gemini South and IGRINS-2 on Gemini North,” says Andreas Seifahrt, Associate Director of Development for the International Gemini Observatory, co-author of the paper, and member of the team who designed and built MAROON-X.
Notes
[1] The nearest star system to us, Proxima Centauri, has three stars circling each other, which changes the dynamics of planet formation and orbits.
More information
This research was presented in a paper titled “Four sub-Earth planets orbiting Barnard’s Star from MAROON-X and ESPRESSO” to appear in The Astrophysical Journal Letters. DOI: 10.3847/2041-8213/adb8d5
The team is composed of Ritvik Basant (University of Chicago), Rafael Luque (University of Chicago, NHFP Sagan Fellow), Jacob L. Bean (University of Chicago), Andreas Seifahrt (International Gemini Observatory/NSF NOIRLab), Madison Brady (University of Chicago), Lily L. Zhao (University of Chicago, NHFP Sagan Fellow), Nina Brown (University of Chicago), Tanya Das (University of Chicago), Julian Stürmer (Heidelberg University), David Kasper (University of Chicago), Rohan Gupta (University of Chicago), and Guðmundur Stefánsson (University of Amsterdam).
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 MAROON-X instrument is attached to 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, where it dissects light from the telescope to capture information about faraway planets.
Credit
International Gemini Observatory/NOIRLab/NSF/AURA/J. Bean
Exoplanets Orbiting Barnard’s [VIDEO] |
This animation shows the orbital dynamics of the Barnard’s Star planetary system. For a century, astronomers have been studying Barnard’s Star in the hope of finding planets around it. First discovered by E. E. Barnard at Yerkes Observatory in 1916, it is the nearest single star system to Earth. Now, using in part the Gemini North telescope, one half of the International Gemini Observatory, partly funded by the U.S. National Science Foundation and operated by NSF NOIRLab, astronomers have discovered four sub-Earth exoplanets orbiting the star. One of the planets is the least massive exoplanet ever discovered using the radial velocity technique, indicating a new benchmark for discovering smaller planets around nearby stars.
Credit
International Gemini Observatory/NOIRLab/NSF/AURA/R. Proctor/J. Pollard
Links
- Read the paper: Four sub-Earth planets orbiting Barnard’s Star from MAROON-X and ESPRESSO
- UChicago press release
- Photos of Gemini North
- Videos of Gemini North
- Check out other NOIRLab Science Releases
Journal
The Astrophysical Journal Letters
Article Title
Four sub-Earth planets orbiting Barnard’s Star from MAROON-X and ESPRESSO
Article Publication Date
11-Mar-2025
Study by UChicago scientists finds four tiny planets around one of our nearest stars
MAROON-X instrument finds evidence for planets around famous Barnard’s Star
University of Chicago
image:
An artist’s conception of the view from one of the four planets orbiting Barnard’s Star. Illustration by R. Proctor/J. Pollard/NOIRLab.
view moreCredit: International Gemini Observatory/NOIRLab/NSF/AURA/R. Proctor/J. Pollard
Astronomers have revealed new evidence that there are not just one but four tiny planets circling around Barnard’s Star, the second-nearest star system to Earth.
The four planets, each only about 20 to 30% the mass of Earth, are so close to their home star that they zip around the entire star in a matter of days. That probably means they are too hot to be habitable, but the find is a new benchmark for discovering smaller planets around nearby stars.
“It’s a really exciting find—Barnard’s Star is our cosmic neighbor, and yet we know so little about it,” said Ritvik Basant, Ph.D student at the University of Chicago and first author on the study. “It’s signaling a breakthrough with the precision of these new instruments from previous generations.”
The finding adds weight to a November study by a team using a different telescope, which had found strong evidence for one planet around Barnard’s Star and hints at others.
The new study, which included scientists with the Gemini Observatory/National Science Foundation NOIRLab, Heidelberg University, and the University of Amsterdam, is published March 11 in The Astrophysical Journal Letters.
Star wobbles
For a century, astronomers have been studying Barnard’s Star in hopes of finding planets around it. First discovered by E. E. Barnard at Yerkes Observatory in 1916, it is the nearest system that has the same configuration we do—i.e., with only one star. (The absolute nearest star system to us, Proxima Centauri, has three stars circling each other, which changes the dynamics of planet formation and orbits).
Barnard’s Star is a type called an M dwarf star, which we now know are extremely numerous in the universe. Scientists, therefore, would like to know more about what kinds of planets they host.
The trouble is that these faraway planets are far too tiny to be seen next to the brilliance of their stars, even with our most powerful telescopes. That means scientists have had to get creative to search for them.
One such effort was led by UChicago Prof. Jacob Bean, whose team created and installed an instrument called MAROON-X, which is attached to the Gemini Telescope on a Hawaiian mountaintop and designed specifically to search for distant planets.
Because stars are so much brighter than their planets, it’s easier to look for effects that planets have on their stars—like monitoring the wind by watching how a flag moves.
MAROON-X looks for one such effect; the gravity of each planet tugs slightly on the star’s position, meaning the star seems to wobble back and forth. MAROON-X measures the color of the light so precisely that it can pick up these minor shifts, and even tease apart the number and masses of the planets that must be circling the star to have this effect.
Basant, Bean, and the team rigorously calibrated and analyzed data taken during 112 different nights over a period of three years. They found solid evidence for three planets around Barnard’s Star.
When the team combined their findings with data from the November experiment by a different team, which was taken by an instrument called ESPRESSO at the Very Large Telescope in Chile, they saw good evidence for a fourth planet.
These planets are likely rocky planets, rather than gas planets like Jupiter, the scientists said. That will be difficult to pin down with certainty; the angle we see them from Earth means we can’t watch them cross in front of their star, which is the usual method to find out if a planet is rocky. But by gathering information about similar planets around other stars, we can make better guesses about their makeup.
However, the team was able to rule out, with a fair degree of certainty, the existence of other planets in the habitable zone around Barnard’s Star.
‘Really exciting’
Barnard’s Star has been called the “great white whale” for planet hunters; several times over the past century, groups have announced evidence that suggested planets around Barnard’s Star, only for them to be later disproved.
But these latest findings, independently confirmed in two different studies by the different instruments ESPRESSO and MAROON-X, mean a much larger degree of confidence than any previous result.
“We observed at different times of night on different days. They’re in Chile; we’re in Hawaii. Our teams didn’t coordinate with each other at all,” Basant said. “That gives us a lot of assurance that these aren’t phantoms in the data.”
These are among the smallest planets yet found with this observing technique. The scientists hope this will mark a new era of finding more and more planets in the universe.
Most of the rocky planets we’ve found so far are much larger than Earth, and they appear to be fairly similar across the galaxy. But there are reasons to think the smaller planets will have more widely varied compositions. As we find more of them, we can begin to tease out more information about how these planets form—and what makes planets likely to have habitable conditions.
The find itself was exciting, too, the scientists said.
“We worked on this data really intensely at the end of December, and I was thinking about it all the time,” Bean said. “It was like, suddenly we know something that no one else does about the universe. We just couldn’t wait to get this secret out.
“A lot of what we do can be incremental, and it’s sometimes hard to see the bigger picture,” he said. “But we found something that humanity will hopefully know forever. That sense of discovery is incredible.”
Additional University of Chicago authors on the paper were postdoctoral fellows Rafael Luque, Lily L. Zhao, Tanya Das, and David Kasper; graduate student Madison Brady; postbaccalaureate student Nina Brown; and masters student Rohan Gupta.
Journal
The Astrophysical Journal Letters
Article Title
Four Sub-Earth Planets Orbiting Barnard's Star from MAROON-X and ESPRESSO
Article Publication Date
11-Mar-2025
Small, faint and 'unexpected in a lot of different ways': U-M astronomers make galactic discovery
University of Michigan
image:
Researchers led by astronomers at the University of Michigan have discovered the smallest and dimmest galaxy to date that's orbiting the Andromeda system, the Milky Way's nearest major galactic neighbor. The newfound galaxy, Andromeda XXXV, is seen within the white ellipse.
(High resolution .tiff file available on request)
Credit: CFHT/MegaCam/PAndAS (Principal investigator: Alan McConnachie; Image processing: Marcos Arias)
A discovery made by a team led by researchers at the University of Michigan tugs at the seams of some key cosmic lessons we thought we had learned from our own galaxy.
This new knowledge comes from the outskirts of Andromeda, the Milky Way's nearest major galactic neighbor, where astronomers have found the system's smallest and dimmest satellite galaxy to date.
This dwarf galaxy, named Andromeda XXXV and located roughly 3 million light-years away, is forcing astronomers to rethink how galaxies evolve in different cosmic environments and survive different epochs of the universe.
Although the discovery bears more questions than answers, that's what happens when you're investigating the universe, said Marcos Arias, the lead author of the report in Astrophysical Journal Letters that details the discovery.
The universe still harbors many mysteries, he said, but this discovery helps correct what we do know and reveals more about what we don't.
"We still have a lot to discover," said Arias, who performed this work as an undergraduate student in the Department of Astronomy and is currently a post-baccalaureate researcher in astronomy and physics.
"There are so many things that we still need to learn—even about what's near to us—in terms of galaxy formation, evolution and structure before we can reverse engineer the history of the universe and understand how we came to be where we are today."
Intergalactic and very tiny
Our Milky Way system also hosts dozens of these satellite or companion galaxies, too, which explains why their story is still being written. These companions are distinct from their massive, central host galaxy, but still close enough to be caught in its gravitational grasp. The satellites are also much, much smaller.
"These are fully functional galaxies, but they're about a millionth of the size of the Milky Way," said the study's senior author, Eric Bell, U-M professor and associate chair of astronomy. "It's like having a perfectly functional human being that's the size of a grain of rice."
Because they're so much smaller, these satellite galaxies are also a lot dimmer and harder to spot. It's only been within the last couple decades that astronomers have had technology sensitive enough to discover most of the Milky Way's known satellites. And it's currently impossible for observers to spot extremely faint satellites that are orbiting hosts farther away than Andromeda, Bell said.
Because of their proximity to us, the Milky Way's satellites have been our only source of information on these tiny galaxies. Although scientists have discovered satellite galaxies in Andromeda before—that's why it's Andromeda XXXV and not Andromeda I—they've been too big and bright to firmly challenge what we've learned from the Milky Way.
"This is, in part, why Marcos' discovery is so important. This type of galaxy was only discoverable around one system, the Milky Way, in the past," Bell said. "Now we're able to look at one around Andromeda and it's the first time we've done that outside our system."
To discover Andromeda XXXV, Arias first pored over massive observational datasets to look for signs of potential companions. Once he had compiled a list of promising candidates, he and Bell secured time on the Hubble Space Telescope to take a closer inspection.
"The opportunities for high-impact research as an undergraduate in the astronomy department at U-M are extensive," Arias said. The work was supported by the National Science Foundation and by NASA through the Space Telescope Science Institute.
Using Hubble, the researchers discovered that not only was Andromeda XXXV a satellite galaxy, but it was small enough to resculpt some of our notions of how galaxies evolve, such as how long they're able to form stars.
"It was really surprising," Bell said. "It's the faintest thing you find around, so it's just kind of a neat system. But it's also unexpected in a lot of different ways."
The team also included researchers from the University of Chicago, Utah Valley University, the Vatican Observatory, the University of La Serena in Chile, the University of Alabama, Montana State University and the Leibniz Institute for Astrophysics Potsdam in Germany.
A celestial whodunit
Although the discovery was surprising, Bell also stressed that it isn't unusual for ideas in astronomy to become more complex once we leave our own backyard. When you have only one system to analyze, you can't be sure what's a generalizable characteristic and what's an idiosyncrasy, he said.
Now, Andromeda XXXV has provided enough strong evidence to start confidently distinguishing those features. The most obvious difference between satellites in the Milky Way and in Andromeda was when they stopped forming stars.
"Most of the Milky Way satellites have very ancient star populations. They stopped forming stars about 10 billion years ago," Arias said. "What we're seeing is that similar satellites in Andromeda can form stars up to a few billion years ago—around 6 billion years."
This information also helped the researchers solve what Bell framed as a murder mystery in Andromeda.
Whether a galaxy is huge or tiny, it needs to have a store of gas that's available to condense into stars. When that gas is gone, star formation stops. A natural question to ask is whether this end comes about by a galaxy's gas supply petering out on its own, or by being sapped away by the larger host.
For the Milky Way's satellites, their earlier shut-off tracks with the unaided option. With star formation lasting longer in Andromeda's small companions, it appears to be the latter.
"It's a little dark, but it's either did they fall or did they get pushed? These galaxies appear to have been pushed," Bell said. "With that, we've learned something qualitatively new about galaxy formation from them."
This extended star formation is even more interesting in the context of Andromeda XXXV's size and the universe's history.
Deep fried cosmology
The universe started out incredibly hot and dense, but by the time of its first billionth birthday, it had expanded and cooled off to the temperature of a cool spring day. This idyllic temperature was also conducive to the universe's gas condensing into stars, which gathered into galaxies.
But as these stars churned out energy, and as black holes formed and gobbled up matter, the universe got really hot again. For small galaxies—galaxies with less mass than about 100,000 suns—this was thought to be a death sentence for star formation. The heat would basically cook off the gas needed to seed stars.
"We thought they were basically all going to be fried because the entire universe turned into a vat of boiling oil," Bell said. But Andromeda XXXV was not fried.
"We thought that it would completely lose its gas, but apparently that doesn't happen, because this thing is about 20,000 solar masses and yet it was forming stars just fine for a few extra billion years."
How it survived is now an open question.
"I don't have an answer," Bell said. "It is also still true that the universe did heat up, we're just learning the consequences are more complicated than we thought."
Organizations like NASA are planning on launching missions capable of discovering more satellite galaxies over the coming years, which will help piece together new solutions.
While Arias and Bell are obviously excited for that and to learn as much as they can from the tools currently at their disposal, they're also comfortable living in the unknown. For Arias, it's what drew him to the field.
"It's the universe," he said. "There will always be something new to discover."
Not only is Andromeda XXXV the dimmest and smallest known satellite galaxy in the Andromeda system, it's about 3 million light-years away, making it very hard to spot. The ellipse within the inset shows where this companion galaxy was discovered.
(High resolution .tiff file available on request)
Credit
CFHT/MegaCam/PAndAS (Principal investigator: Alan W. McConnachie; Image Processing: Marcos Arias)
This map shows the Andromeda galaxy, M31, and its satellites. The newly discovered Andromeda XXXV companion galaxy is highlighted in bold red text.
(High resolution .tiff file available on request)
Credit
J. M. Arias et al. Astrophys. J. Lett. (2025) DOI: 10.3847/2041-8213/adb433
Journal
The Astrophysical Journal Letters
Article Title
Andromeda XXXV: The Faintest Dwarf Satellite of the Andromeda Galaxy
Article Publication Date
11-Mar-2025
Rice research on super-Earths and mini-Neptunes suggests more Earth-like planets may exist
Rice University
image:
From left to right, Andre Izidoro, assistant professor of Earth, environmental and planetary sciences, and Sho Shibata, a postdoctoral fellow of Earth, environmental and planetary sciences at Rice University.
view moreCredit: Rice University.
A new study by Rice University researchers Sho Shibata and Andre Izidoro presents a compelling new model for the formation of super-Earths and mini-Neptunes — planets that are 1 to 4 times the size of Earth and among the most common in our galaxy. Using advanced simulations, the researchers propose that these planets emerge from distinct rings of planetesimals, providing fresh insight into planetary evolution beyond our solar system. The findings were recently published in The Astrophysical Journal Letters.
For decades, scientists have debated how super-Earths and mini-Neptunes form. Traditional models have suggested that planetesimals — the tiny building blocks of planets — formed across wide regions of a young star’s disk. But Shibata and Izidoro suggest a different theory: These materials likely come together in narrow rings at specific locations in the disk, making planet formation more organized than previously believed.
“This paper is particularly significant as it models the formation of super-Earths and mini-Neptunes, which are believed to be the most common types of planets in the galaxy,” said Shibata, a postdoctoral fellow of Earth, environmental and planetary sciences. “One of our key findings is that the formation pathways of the solar system and exoplanetary systems may share fundamental similarities.”
Using advanced N-body simulations — computer models that analyze how objects interact through gravity — the researchers studied planet formation within two distinct regions: one inside 1.5 astronomical units (AU) of the host star and another beyond 5 AU, near the water snowline. The simulations tracked the collisions, growth and migration of planetesimals over millions of years. The results revealed that super-Earths primarily form through planetesimal accretion in the inner disk, while mini-Neptunes develop beyond the snow line, mainly via pebble accretion.
“Our results suggest that super-Earths and mini-Neptunes do not form from a continuous distribution of solid material but rather from rings that concentrate most of the mass in solids,” said Izidoro, an assistant professor of Earth, environmental and planetary sciences. “ Related research at Rice has explored aspects of this idea, but this new paper brings these concepts together into a single, coherent picture.”
The researchers’ model successfully replicates key features of exoplanetary systems, including the “radius valley” — a noticeable scarcity of planets around 1.8 times the size of Earth. Instead, exoplanets tend to cluster into two size groups: roughly 1.4 and 2.4 times Earth’s size. Their model explains this gap by predicting that planets smaller than 1.8 times the Earth’s radius are mostly rocky super-Earths, while larger ones are water-rich mini-Neptunes, aligning closely with real-world observations.
The research also provides insight into size uniformity observed in multiplanet systems.Many exoplanetary systems show a “peas-in-a-pod” pattern, where planets within the same system are strikingly similar in size. The ring model naturally produces this uniformity by controlling how planets form and grow within their respective rings.
Shibata and Izidoro’s simulations also align with observed distributions of planetary orbits, reinforcing the idea that planets emerge from specific locations rather than being randomly scattered across the disk.
Beyond explaining these observations, the model also allows for predictive analysis of planetary formation and even hints at the potential for other Earth-like planets. Izidoro said although it would be rare, rocky planets in the habitable zone could form through late-stage giant impacts, similar to how Earth and its moon formed.
“We can push our model further and use it to make predictions about the types of planets expected at Earth-sun equivalent distances — regions currently beyond the reach of observations,” Izidoro said. “Based on our predictions, up to about 1% of super-Earth and mini-Neptune systems could host Earth-like planets within the habitable zone of their stars. While this fraction is relatively low given how common super-Earths and mini-Neptunes are, it implies an occurrence rate of approximately one Earth-like planet per 300 sun-like stars.”
Looking ahead, these findings could have profound implications for future exoplanet research.
“These predictions will be tested with future telescopes, providing crucial insights into planetary formation and habitability,” Shibata said. “If future observations confirm our predictions, it could completely change our understanding of how planets form — not just in our galaxy but throughout the universe.”
Journal
The Astrophysical Journal Letters
Article Title
Formation of Super-Earths and Mini-Neptunes from Rings of Planetesimals
No comments:
Post a Comment