Gliese 251 is an early red dwarf star, ranking as the 74th closest star system to our Sun.
An artistic interpretation of the Gliese 251 system. Featuring Gliese 251c (left), its host star (right), and the already discovered planet Gliese 251b (center). Image credit: Michael Marcheschi / m2design.
You can find Gliese 251 as a bright M dwarf star, located at a distance of 5.58 parsecs (18 light years) in the constellation of Gemini.
Also known as GJ 251, HD 265866, or Wolf 294, this star is believed to host at least two super-Earths, Gliese 251b and Gliese 251c.
Initially discovered in 2020, Gliese 251b has a mass of 3.85 Earth masses and completes an orbit in 14.2 days.
The newly identified exoplanet, Gliese 251c, boasts a mass of 3.84 times that of Earth and has an orbital period of 53.6 days.
“With so many exoplanets now known, discovering new ones may not seem significant,” remarked Paul Robertson, an astronomer at the University of California, Irvine.
“The exceptional aspect is that its host star is nearby, roughly 18 light-years distant. From a cosmic perspective, it’s essentially in our neighborhood.”
Gliese 251c was detected using the Habitable Zone Planet Finder (HPF), a state-of-the-art near-infrared spectrometer mounted on the Hobby-Eberly Telescope at McDonald Observatory in Texas.
This planetary signal was subsequently validated using the NEID spectrometer at Kitt Peak National Observatory in Arizona.
Corey Beard, Data Scientist at Design West Technologies, states:
“While the discovery is statistically significant, we are still assessing the state of the planet due to instrument and methodological uncertainties.”
“Direct imaging of this candidate will rely on the next generation of telescopes and community investment.”
Given Gliese 251c’s closeness to Earth, it stands out as a prime candidate for future direct imaging studies utilizing the Thirty Meter Telescope (TMT).
The TMT, with its large mirror, could potentially directly image dim exoplanets like Gliese 251c and verify the presence of water.
“TMT is anticipated to be the only telescope capable of capturing such details. These images will pertain to exoplanets,” Dr. Beard added.
“Such imaging isn’t feasible with smaller telescopes.”
The results from the research team were published in Astronomy Magazine.
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Corey Beard et al. 2025. Discovery of a nearby super-Earth candidate located in the habitable zone, suitable for direct imaging. A.J. 170, 279; doi: 10.3847/1538-3881/ae0e20
Rocky, Earth-sized planets in our Milky Way may be surrounded by atmospheres, with new research indicating a strong possibility of liquid water on their surfaces, supporting the potential for life.
Two separate papers, to be released on Monday in the Astrophysical Journal Letters, focus on the TRAPPIST-1 system, which contains seven rocky planets orbiting a single star. Both studies present initial findings from NASA’s James Webb Space Telescope, suggesting that one planet, TRAPPIST-1e, could possess a nitrogen-rich atmosphere, although further research is necessary to confirm this.
These findings represent significant progress in the search for extraterrestrial life both within our solar system and beyond.
Recently, NASA revealed that rock samples from Mars may harbor evidence of ancient microorganisms. Presently, Mars has a thin atmosphere made primarily of carbon dioxide, nitrogen, and argon, but billions of years ago, it likely possessed a much thicker atmosphere that allowed liquid water to exist on its surface.
For quite some time, scientists have maintained that water is a crucial element for life.
For a planet or moon to retain water in liquid form, it must have an atmosphere that prevents instant evaporation into space. This makes the search for exoplanet atmospheres one of the most exciting and promising areas of astronomical research.
“Ultimately, our goal is to identify planets that can support life,” stated Ryan McDonald, an exoplanet astronomer at St Andrews University, Scotland, and co-author of both studies. “To do this, we first need to identify whether these planets have atmospheres.”
The TRAPPIST-1 system is located 40 light-years from Earth and has been extensively studied since its discovery in 2016, as some of its planets may have conditions suitable for extraterrestrial life.
Specifically, TRAPPIST-1e is thought to reside in the so-called “habitable zone,” where liquid water could be present on the surface—not too close to the star to be scorching hot and not too far to freeze.
In a recent study, astronomers utilized NASA’s James Webb Space Telescope to observe four “transits” of TRAPPIST-1e, which occur when the planet passes in front of its star. While the telescope did not directly detect the planet’s atmosphere, it measured how light passing through the atmosphere was absorbed, if one is present.
Like a prism, light can be split into different color bands across the spectrum, and variations in how particular colors are filtered or absorbed can help identify the presence of specific atoms or gas molecules.
For instance, if a specific color is absorbed, it may indicate a high concentration of carbon dioxide, while other color changes could suggest the presence of hydrogen, oxygen, methane, or nitrogen.
“If no color variation is present, the planet is likely just a barren rock,” McDonald noted. “Barren rocks won’t show any color changes in response to light.”
During the four transits, researchers found no signs of a hydrogen-rich atmosphere surrounding TRAPPIST-1e, nor did they observe any indications of a carbon dioxide-rich atmosphere. However, observations from the Webb telescope suggest a potential nitrogen-rich atmosphere.
“This is an exciting development that will significantly narrow down the prospects for a more Earth-like atmosphere,” remarked Caroline Piaulett Graeb, a postdoctoral researcher at the University of Chicago who was not involved in the new research.
Earth’s atmosphere is composed of a significant amount of nitrogen gas. Titan, one of Saturn’s moons, has an atmosphere primarily made of nitrogen and is believed by NASA to harbor a vast underground sea. Although it may be habitable, the methane-rich environment of the moon differs greatly from conditions on Earth.
Piaulet-Ghorayeb, the lead author of a study published last month in the Astrophysical Journal, focused on another planet in the TRAPPIST-1 system, TRAPPIST-1d. This planet is also located within the habitable zone, but the study found no evidence of common Earth-like molecules such as water, carbon dioxide, or methane.
Studying these distant worlds poses significant challenges.
The TRAPPIST-1 star is small and exceptionally active, producing considerable background noise that complicates researchers’ efforts. McDonald and his team dedicated over a year to analyzing data from the Webb telescope in order to isolate and identify chemical signatures from TRAPPIST-1e and its star.
To confirm the presence of an atmosphere, McDonald and his colleagues plan to observe TRAPPIST-1e during an additional 15 transits over the coming years.
They are also looking into three other planets, TRAPPIST-1f, TRAPPIST-1g, and TRAPPIST-1h, which are located further out in the system.
This research aims to bring scientists closer to answering some of the most persistent questions regarding exoplanets and the existence of life.
“We have not yet reliably confirmed the atmosphere of rocky planets outside our solar system, but it opens the door to studying temperate planets,” said Piaulett-Ghorayeb. “However, there is still much to explore.”
Astronomers are making strides in exploring the TRAPPIST-1 system with the NASA/ESA/CSA James Webb Space Telescope, showcasing its remarkable capability to glean detailed data about the exoplanet atmospheres and effectively utilize this information. The initial findings stem from Webb’s observation of TRAPPIST-1e. Although the first four observations by Webb are not adequate to fully assess the atmosphere, scientists are using the data to refine the possibilities for these planets, including the presence of oceans similar to those on Earth and a methane-rich environment akin to Saturn’s moon Titan. Meanwhile, additional innovative observations from Webb are ongoing, revealing the unique characteristics of TRAPPIST-1e.
The Earth-sized Exoplanet TRAPPIST-1E is illustrated in the bottom right as it eclipses the flare host star in this artist’s representation of the TRAPPIST-1 system. Image credits: NASA/ESA/CSA/STSCI/JOSEPH OLMSTED, STSCI.
TRAPPIST-1 is a cool dwarf star located in the Aquarius constellation, approximately 38.8 light-years away.
The stars are only slightly larger than Jupiter and possess a mere 8% of the solar mass. They rotate rapidly and emit UV energy flares.
TRAPPIST-1 harbors seven transiting planets designated TRAPPIST-1b, c, d, e, f, g, and h.
All these planets are comparable in size to Earth and Venus, or slightly smaller, with remarkably short orbital periods: 1.51, 2.42, 4.04, 6.06, 9.21, 12.35, and 20 days, respectively.
It is possible that they could be tidally locked, meaning the same side is always facing the host star, resulting in a perpetual day and night side for each TRAPPIST-1 planet.
Among the seven planets, TRAPPIST-1E is of particular interest if it possesses an atmosphere, as its surface water is situated at a theoretically viable distance from the star.
The Space Telescope Science Institute and colleague Dr. Néstor Espinoza aimed the Webb’s NIRSpec (near-infrared spectrometer) instrument at TRAPPIST-1e during its transits in front of the star.
As starlight filters through the planet’s atmosphere, it can be partially absorbed, revealing the specific chemicals present by the resulting dips in the light spectrum that reaches Webb.
As more transits are analyzed, the clarity regarding the atmospheric composition improves.
With only four transits analyzed thus far, numerous possibilities remain open for TRAPPIST-1E, though researchers speculate that it lacks a significant primary atmosphere.
Given TRAPPIST-1’s active nature and frequent flares, it’s not unexpected that the potential hydrogen-helium atmosphere of the planet could have been stripped away by stellar radiation.
However, many planets, like Earth, develop a denser secondary atmosphere after losing their initial one.
TRAPPIST-1E may not have the capacity for this and could potentially lack a secondary atmosphere.
“We have devised a novel method to analyze Webb’s data to assess the potential atmosphere and surface conditions of TRAPPIST-1E,” said the scientist.
It appears unlikely that TRAPPIST-1e’s atmosphere is largely composed of carbon dioxide, reminiscent of Venus’s thick atmosphere or Mars’s thinner one.
Nonetheless, astronomers should be cautious, as there are no direct parallels to our solar system.
“Because TRAPPIST-1 is significantly different from our Sun, the surrounding planetary systems also exhibit notable differences, posing challenges to both observational and theoretical frameworks,” remarked Dr. Nicole Lewis of Cornell University.
“If TRAPPIST-1E has liquid water, it would require a greenhouse effect. This effect incorporates various gases, especially carbon dioxide, which help stabilize the atmosphere and maintain a warm environment on the planet.”
“A minimal greenhouse effect is beneficial, and measurements do not exclude the presence of carbon dioxide necessary to preserve water on the surface.”
The team’s analysis suggests that water could exist as global oceans or be distributed in smaller, ice-encased regions at midday.
This is due to the size of the TRAPPIST-1 planets and their orbital sizes, all of which are thought to be tidally locked, with one side perpetually facing the star and the other shrouded in darkness.
“They’re remarkable,” stated Dr. Anna Glidden, an astronomer at the Kavli Institute for Astrophysics and Space Research at MIT.
“This is an astounding measurement of starlight around an Earth-sized planet located 40 light-years away, providing insights into potential life there if conditions permit.”
“It’s thrilling to be part of this new era of exploration.”
Néstor Espinoza et al. 2025. JWST-TST Dreams: NIRSpec/Prism transmission spectroscopy of the planet TRAPPIST-1e. ApJL 990, L52; doi: 10.3847/2041-8213/adf42e
Anna Glidden et al. 2025. JWST-TST Dreams: Secondary atmosphere constraints of the habitable zone planet TRAPPIST-1e. ApJL 990, L53; doi: 10.3847/2041-8213/adf62e
The icy dwarf planet Ceres might have been habitable in the past
NASA/Jet Propulsion Research Institute (JPL)
The dwarf planet Ceres seems desolate and frozen, yet, billions of years after its creation, it could have housed a warm, habitable interior.
Sam Course Building from Arizona State University notes that while we can’t definitively say life could arise on Ceres, its past conditions possibly allowed for the survival of life.
Previous research indicates that Ceres may contain water ice and organic compounds, suggesting potential for life. In this study, however, researchers explored what these potential alien life forms could have consumed. Instead of feeding on other organisms, they might have derived energy directly from chemical molecules, similar to microorganisms found in hydrothermal vents in Earth’s oceans. Could analogous microorganisms have lived in Ceres’ ancient oceans?
The team simulated Ceres’ history and found that over 500 million to 2 billion years ago, pores near its hot core could have released liquid which mingled with the cold ocean waters. This interaction might have provided essential chemical “food” for microorganisms.
To seek past or current life in the solar system, Amanda Hendrix from the Institute of Planetary Sciences emphasizes the importance of examining worlds like Ceres that either currently have or once possessed oceans.
Interestingly, the types of life-sustaining conditions described by the team might also have existed on other ice-like bodies the size of Ceres. This suggests that the number of potentially habitable planets in evolution could be greater than previously thought.
“If Ceres was habitable in the past, then it’s probable that a multitude of asteroids and moons were also habitable, and many may still be today,” states team member Joe O’Rourke from Arizona State University.
Thus, habitability may simply result from readily available ingredients that appear to be common in the solar system.
However, many aspects remain uncertain, especially concerning Ceres itself. Researchers believe that accurate chemical analyses of surface minerals will enhance their models, but no spacecraft capable of conducting such analyses has landed on Ceres yet.
The planetary candidate, Alpha Centauri AB, may be a gas giant orbiting at a distance of one to two times that of the Earth from the Sun, as indicated in two research papers. Astrophysics Journal Letter. If verified, this planet would be the closest known to Earth within the habitable zone of a Sun-like star. Nonetheless, since it is a gas giant, astronomers do not believe it could support life as we understand it.
Artist’s rendering of the gas giant Alpha Centauri A. Image credits: NASA/ESA/CSA/STSCI/Robert L. Hurt, Caltech & IPAC.
Alpha Centauri resides in the Centaurus constellation and represents the nearest star system to Earth.
Also referred to as Rigil Centaurus, Rigil Kent, and Griese 559, this system includes a bright binary star pair, Alpha Centauri A and Alpha Centauri B, alongside a fainter red star known as Alpha Centauri C.
The two prominent stars are approximately 4.35 light-years away, while Alpha Centauri C, commonly called Proxima Centauri, is slightly nearer at about 4.23 light-years.
In comparison to the Sun, Alpha Centauri A is a G2-type star similar in nature, but slightly larger (1.1 times the size of the Sun and around 1.5 times its luminosity).
Alpha Centauri B, classified as a K1-type star, is slightly smaller and less luminous (approximately 0.9 times the mass of the Sun, with about 45% of its visual brightness).
These two stars orbit around a common center of gravity approximately every 80 years, maintaining a minimum distance of about 11 times that of the Earth-Sun distance.
Astronomers study these stars closely along with our nearest interstellar neighbor, Proxima Centauri, making them prime targets in the search for potentially habitable planets.
“This proximity offers the best chance to gather data on planetary systems beyond our own,” stated Dr. Charles Beichman from NASA’s Jet Propulsion Laboratory and the Exoplanet Science Institute at IPAC Astronomy Center in California.
“However, the brightness and swift motion of these stars present significant challenges in observation, even for the world’s most advanced space telescopes.”
The Alpha Centauri star system captured by different terrestrial and space-based observatories: DSS, Hubble Space Telescope, and James Webb Space Telescope. While the DSS shows the triple system as one light source, Hubble distinguishes between Alpha Centauri A and B. Webb’s Milimask image mitigates glare from Alpha Centauri A via a coronagraphic mask. Image credits: NASA/ESA/CSA/ANIKET SANGHI, CALTECH/CHAS BEICHMAN, NEXSCI, NASA & JPL-CALTECH/DIMITRI MAWET, CALTECH/JOSEPH DEPASQUALE, STSCI.
The first observations of this system occurred in August 2024, employing a Coronagraphic Mask with Webb’s Mid-Infrared Instrument (MIRI) to reduce the brightness of Alpha Centauri A.
The presence of nearby companion star Alpha Centauri B added complexity to the analysis, but astronomers successfully subtracted the light from both stars, uncovering objects that were more than 10,000 times dimmer than Alpha Centauri A.
On the other hand, an initial detection was promising, but further data was required for a definitive conclusion.
However, subsequent observations in February and April of 2025 did not unveil any objects akin to those detected in August 2024.
“We are facing a case of disappearing planets,” remarked Dr. Aniket Sangi from Caltech.
“To unravel this mystery, we employed computer models simulating millions of potential orbits, taking into account the insights gained from observing planets and their absence.”
In the simulations, the team incorporated the 2019 sightings of potential exoplanet candidates reported by the ESO’s Very Large Telescope, alongside new data from Webb, considering the gravitational stability of orbits influenced by Alpha Centauri B.
“The non-detections in the second and third rounds with Webb were not unexpected,” stated Sangi.
“In many simulated orbits, the planet was positioned too close to the star, rendering it invisible to Webb during both February and April 2025.”
“Based on mid-infrared observations of planetary brightness and orbital simulations, this gas giant could have a mass similar to Saturn, orbiting Alpha Centauri A at a distance one to two times greater than that between the Sun and Earth.”
“If confirmed, the potential planets identified in Webb’s Alpha Centauri images will represent a significant milestone in exoplanet imaging efforts,” Sangi added.
“Of all directly imaged planets, this would be the closest star we have ever observed.”
“Moreover, it would be the nearest to our home, with gas giants in our solar system that are similar in temperature and age to Earth.”
“The mere existence of two closely separated star systems poses intriguing challenges to our understanding of planetary formation, survival, and evolution within chaotic environments.”
If substantiated by further observations, these findings could reshape the field of exoplanet science.
“This will become a pivotal object in exoplanet research, offering multiple opportunities for detailed characterization by Webb and other observatories,” Dr. Beichman concluded.
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Charles Beichman et al. 2025. The Neighbor World: Imaging a giant planet candidate, orbital and physical properties of CEN A, and habitable zones at the exozodiacal upper limit. ApJL in press; Arxiv: 2508.03814
Aniket Sangi et al. 2025. The Neighbor World: Imaging a giant planet candidate in the habitable zone of Cen A. II. Binary Star Modeling, Planetary and Exozodiacal Search, and Sensitivity Analysis. ApJL in press; Arxiv: 2508.03812
Planetary researcher Tereza Konstantinou and colleagues at the University of Cambridge examined the chemical composition of Venus’s atmosphere and found that the planet’s interior today is too dry to support oceans on its surface. I reasoned that it wasn’t. Rather, Venus is thought to have been a scorching and harsh world throughout its history.
This composite image taken by JAXA’s Akatsuki spacecraft shows Venus. Image credit: JAXA / ISAS / DARTS / Damia Bouic.
From a distance, Venus and Earth look like siblings. It is a rocky planet, about the same size as Earth.
But up close, Venus is more like its evil twin. Venus is covered in thick clouds of sulfuric acid, and its surface has an average temperature of nearly 500 degrees Celsius.
Despite these extreme conditions, astronomers have wondered for decades whether Venus once had a liquid ocean capable of supporting life, or whether some mysterious form is now hidden within its thick clouds. I have been investigating whether there are “airborne” life forms.
“Until we send a probe at the end of this decade, we won’t know if Venus could support life, or if it actually could support life,” Constantineau said.
“However, given that Venus likely did not have an ocean, it is unlikely that Venus could have supported Earth-like life that required liquid water.”
When looking for life elsewhere in the galaxy, astronomers focus on planets orbiting their host stars within the habitable zone. There, temperatures are such that liquid water can exist on the planet’s surface.
Venus provides strong constraints on where this habitable zone exists around the star.
“Despite being our closest planet, Venus is important for exoplanet science because it allows us to explore planets at the edge of the habitable zone that have evolved quite differently than us. Because it gives us a unique opportunity,” Constantinou said.
A dichotomous climate pathway for Venus is proposed. Image credit: Konstantinou others., doi: 10.1038/s41550-024-02414-5.
There are two main theories about how conditions on Venus have evolved since its formation 4.6 billion years ago.
First, surface conditions on Venus were once warm enough for liquid water to exist, but a runaway greenhouse effect caused by widespread volcanic activity has caused Venus to become increasingly hot. is.
The second theory is that Venus was born at such a high temperature that liquid water could not condense on its surface.
“Both of these theories are based on climate models, but we wanted to take a different approach based on observations of Venus’s current atmospheric chemistry,” Constantinou said.
“To keep Venus’s atmosphere stable, the chemicals that are removed from the atmosphere must also be replaced, because the interior and exterior of Venus are constantly in chemical communication with each other.”
The researchers calculated the current rate of destruction of water, carbon dioxide, and carbonyl sulfide molecules in Venus’s atmosphere, which must be repaired by volcanic gases to keep the atmosphere stable.
Volcanic activity provides a window into the interiors of rocky planets like Venus through the supply of gases into the atmosphere.
As magma rises from the mantle to the surface, it releases gases from deep within the planet.
Since the Earth’s interior is rich in water, volcanic eruptions on Earth produce mostly water vapor.
However, based on the composition of the volcanic gases needed to maintain Venus’s atmosphere, scientists have found that Venus’s volcanic gases are at most 6% water.
These dry eruptions suggest that Venus’s interior, the source of the magma that releases volcanic gases, is also dry.
By the end of this decade, NASA’s DAVINCI mission will be able to test and confirm whether Venus has always been an arid and inhospitable planet by sending a series of flybys and probes to the surface. Dew.
The results could help astronomers narrow their search for planets capable of supporting life in orbits around other stars in the galaxy.
“If Venus was habitable in the past, that means other planets we have already discovered may also be habitable,” Constantineau says.
“Instruments like NASA/ESA/CSA’s James Webb Space Telescope are ideal for studying the atmospheres of planets close to their host stars, like Venus.”
“But if Venus was never habitable, Venus-like planets elsewhere are less likely to have habitable conditions or candidates for life.
“We wanted to know that Venus was once a planet much closer to ours, so it’s sad in a way to find out that it wasn’t, but in the end it turned out that most of it was a planet closer to Earth. It would be more profitable to focus our exploration on planets that could probably support life, at least life as we know it. ”
of study Published in this month’s magazine natural astronomy.
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T. Constantinou others. The arid interior of Venus, constrained by atmospheric chemistry. Nat Astronpublished online on December 2, 2024. doi: 10.1038/s41550-024-02414-5
This article is based on a press release provided by the University of Cambridge.
LHS 1140b is the second-closest temperate transiting exoplanet to Earth, with temperatures cold enough for liquid water to exist on its surface.
LHS 1140b could be a completely icy world, like Jupiter's moon Europa (left), or it could be an icy world with a liquid ocean and cloud-like atmosphere (centre). Image courtesy of B. Gougeon / University of Montreal.
LHS 1140 is a cool, low-mass star located about 39 light-years from Earth in the constellation Cetus.
Also known as Gliese 3053, GJ 3053 and 2MASS J00445930-1516166, the star is about one-fifth the size of our Sun and is about 5 billion years old.
LHS 1140 is known to be home to three exoplanets: LHS 1140b, LHS 1140c, and LHS 1140d.
Earlier this year, astronomers reported new mass and radius estimates for LHS 1140b with extraordinary precision, matching estimates for the better-known TRAPPIST-1 planet: 1.7 times the size and 5.6 times the mass of Earth.
One of the key questions about LHS 1140b was whether it was a mini-Neptune-type exoplanet or a super-Earth.
The latter scenario included the possibility of the existence of so-called Hythean worlds with global liquid oceans enveloped in a hydrogen-rich atmosphere, which would show a clear atmospheric signal observable using Webb.
Analysis of Webb's new observations completely rules out the mini-Neptune scenario and provides compelling evidence suggesting that exoplanet LHS 1140b is a super-Earth, possibly with a nitrogen-rich atmosphere.
If confirmed, this result would make LHS 1140b the first temperate planet to show evidence of a secondary atmosphere that formed after the planet's initial formation.
Estimates based on all the accumulated data suggest that LHS 1140b is less dense than expected for a rocky planet with an Earth-like composition, and that 10-20% of its mass may be made up of water.
The discovery indicates that LHS 1140b is a fascinating watery world, possibly similar to a snowball or ice planet, and the planet's expected synchronous rotation means that a region of the planet's surface could always harbor a liquid ocean at its substellar point, facing the system's host star.
Artist's impression of planetary system LHS 1140. Image courtesy of Sci.News.
“Among the currently known temperate exoplanets, LHS 1140b may be the best candidate for future indirect confirmation of the existence of liquid water on the surface of an alien world outside our solar system,” said Charles Cadieux, a doctoral student at the University of Montreal.
“This will be a major milestone in the search for potentially habitable exoplanets.”
Although still preliminary, the presence of a nitrogen-rich atmosphere on LHS 1140b suggests that the planet could retain a significant amount of atmosphere, creating the conditions for liquid water to exist. This finding makes the water-world/snowball scenario the most plausible.
Current models suggest that if LHS 1140b had an Earth-like atmosphere, it would be a snowball planet with a huge bull's-eye shaped ocean about 4,000 km in diameter, equivalent to half the surface area of the Atlantic Ocean.
Surface temperatures in the core of this alien ocean could reach a comfortable 20 degrees Celsius.
LHS 1140b has favorable conditions for a potential atmosphere and liquid water, making it an excellent candidate for future habitability studies.
“The planet provides a unique opportunity to study worlds that could potentially support life, as it is located in the habitable zone of its star and likely has an atmosphere capable of retaining heat and supporting a stable climate,” the astronomers said.
In a new study, astronomers from Yale University and the Massachusetts Institute of Technology examined the coupled distribution of spin and orbital orbits of exoplanets in binary and triple star systems.
An artist's impression of a giant exoplanet and its two parent stars. Image credit: Sci.News.
An important subset of all known exoplanet systems include host stars with one or more bound stellar companions.
These multistar systems can span a vast range of relative configurations and provide rich insights into the processes by which stars and planets form.
“We showed for the first time that a system where everything is coordinated stacks up unexpectedly,” he said. Dr. Malena Ricean astronomer at Yale University.
“The planet orbits in exactly the same direction as the first star rotates, and the second star orbits its system in the same plane as the planet.”
Dr. Rice and his colleagues used a variety of sources, including the Gaia DR3 catalog of high-precision stellar astronomical measurements, the planetary system composite parameter table from the NASA Exoplanet Archive, and the TEPCat catalog of spin-orbit angle measurements of exoplanets. to create a 3D geometric shape. Number of planets in a binary star system.
Astronomers found that nine of the 40 star systems they studied were in “perfect” locations.
“This could indicate that planetary systems prefer to move toward ordered configurations,” Rice said.
“This is also good news for life forming in these systems.”
“A star's companion star with a different alignment can wreak havoc on a planetary system, overturning the planet or flash-heating the planet over time.”
“And what would the world look like on a warmer Tatooine?”
“During some seasons of the year, there would be continuous daylight, and one star would illuminate one side of the Earth, and another star would illuminate the other side.”
“But that sun's light isn't always scorching, because one of the stars is farther away.”
“At other times of the year, both stars will illuminate the same side of the Earth, and one star will appear much larger than the other.”
Using data from NASA’s Transiting Exoplanet Survey Satellite (TESS), astronomers discovered a habitable zone planet orbiting nearby red dwarf star TOI-715 every 19.3 days and characterized its characteristics. I made it clear. They also demonstrated that a second, smaller exoplanet with a period of 25.6 days may exist, located just inside the outer edge of TOI-715’s habitable zone. This system represents the first of his TESS discoveries to fall within this most conservative and widely applicable habitable zone.
Artist’s impression of the super-Earth exoplanet TOI-715b. Image credit: NASA/JPL-Caltech.
TOI-715 is an M dwarf star of spectral type M4 located approximately 137 light-years away in the constellation Urae.
The star, also known as TIC 271971130, is about 6.6 billion years old, making it older than the Sun.
TOI-715 includes the super-Earth exoplanet TOI-715b and the smaller terrestrial exoplanet candidate TOI-715c.
“TOI-715b is about 1.5 times wider than Earth and orbits within the habitable zone around its parent star,” said Georgina Dransfield, an astronomer at the University of Birmingham.
“This is the distance from the star that can give the planet the right temperature for liquid water to form on its surface.”
“Of course, for surface water to exist, several other factors have to be in place, especially for us to have a suitable atmosphere.”
“However, the conservative habitable zone (which may be narrower and more robustly defined than the broader ‘optimistic’ habitable zone) is a It ranks first.”
“A smaller planet, TOI-715c, may be only slightly larger than Earth and may exist just inside the conservative habitable zone.”
“TOI-175b joins the list of habitable zone planets that could be scrutinized more closely by Webb, perhaps also for atmospheric signatures,” the astronomers said.
“A lot depends on other properties of the planet, such as how heavy it is and whether it can be classified as a water world. Its atmosphere, if any at all, is more massive, denser, and has an atmosphere. It’s less pronounced than the atmosphere, and much less difficult to detect. Drier worlds are likely to keep their inconspicuous atmospheres close to the surface.”
“If the possibility of a second Earth-sized planet in this system is confirmed, it would be the smallest habitable zone planet ever discovered by TESS.”
“This discovery also exceeds TESS’s initial expectations by discovering an Earth-sized world within the habitable zone.”
This finding is reported in the following article: paper inside Royal Astronomical Society Monthly Notices.
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Georgina Dransfield other. 2024. Earth's habitable zone planet hosted by the M4 star TOI-715 near the ecliptic south pole. MNRAS 527 (1): 35-52; doi: 10.1093/mnras/stad1439
Astronomers at NASA and the University of Washington estimated the total internal heating rate and depth to potential subsurface oceans for 17 potentially cold ocean planets. These planets are low-mass exoplanets with surface temperatures and densities consistent with icy surfaces and large amounts of water. content. Like the icy moons of our solar system, these planets could be astrobiologically important worlds with habitable environments beneath their icy surfaces.
This artist’s impression shows Proxima b orbiting Proxima Centauri, the closest star to our solar system at just 4.23 light years. The double star Alpha Centauri AB also appears in the image between the exoplanet and Proxima itself. Image credit: M. Kornmesser / ESO.
Ocean planets have been proposed as a class of low-density terrestrial exoplanets with significant liquid water layers.
They exist in different climatic states, including ice-free, partially ice-covered, and completely frozen surfaces.
“Our analysis suggests that the surfaces of these 17 alien worlds may be covered in ice, but they are affected by internal heating due to the decay of radioactive elements and tidal forces from their host stars,” said NASA Goddard researcher Dr. Lynne Quick. “We predict that it will receive enough water to maintain its internal ocean.” Space flight center.
“Due to the amount of internal heating the planets experience, all the planets in our study may also exhibit polar volcanic eruptions in the form of geyser-like plumes.”
Dr. Quick and his colleagues examined the status of 17 confirmed exoplanets. These planets are roughly Earth-sized but less dense, suggesting they may have significant amounts of ice and water instead of dense rock.
Although the exact composition of these planets remains unknown, all initial estimates of surface temperatures from previous studies indicate that they are much cooler than Earth, and their surfaces may be covered with ice. This suggests that there is a possibility that
The authors improved their estimates of each exoplanet’s surface temperature by recalculating them using the known surface brightness and other properties of Europa and Enceladus as models.
They also estimated the total internal heating of these exoplanets by using the shape of each exoplanet’s orbit to capture the heat generated from the tides and adding it to the heat expected from radioactive activity. did.
Because oceans cool and freeze at the surface while being heated from within, estimates of surface temperature and total heating provide information about the thickness of each exoplanet’s ice layer.
Finally, they compared these numbers to Europa’s and used Europa’s estimated level of geyser activity as a conservative baseline for estimating the exoplanet’s geyser activity.
They predict surface temperatures will be up to 33 degrees Celsius (60 degrees Fahrenheit) cooler than previous estimates.
Artist’s impression of the planetary system LHS 1140. Image credit: Sci.News.
Estimated ice shell thicknesses ranged from approximately 58 m (190 ft) for Proxima b and 1.6 km (1 mi) for LHS 1140b to 38.6 km (24 mi) for LHS 1140b. MOA-2007-BLG-192Lbcompared to an estimated European average of 29 km (18 mi).
The estimated geyser activity was only 8 kg/s for Kepler 441b, 2,000 kg/s for Europa, 290,000 kg/s for LHS 1140b, and 6 million kg/s for Proxima b.
“Our models predict that oceans could be found relatively close to the surfaces of Proxima b and LHS 1140b, and that geyser activity rates could exceed those of Europa by hundreds to thousands of times. “The telescope has the best chance of detecting geological activity on these planets because of their presence,” said Dr. Quick.
“This activity can be seen when an exoplanet passes in front of its star. Certain colors of the star’s light can be dimmed or blocked by water vapor from geysers. there is.”
“If water vapor is detected sporadically and the amount of water vapor detected changes over time, it would suggest the presence of a cryovolcanic eruption.”
“Water may contain other elements and compounds, which could reveal whether it can support life.”
“Elements and compounds absorb light of certain characteristic colors, so analysis of starlight allows scientists to determine the composition of geysers and assess the potential habitability of exoplanets. Become.”
a paper Regarding the survey results, astrophysical journal.
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Lynne C. Quick other. 2023. Prospects for polar volcanic activity on cold ocean planets. APJ 956, 29; doi: 10.3847/1538-4357/ace9b6
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