Super-Earth Exoplanet Discovered in Habitable Zone May Harbor Liquid Water
Astronomers from the University of California, Irvine have discovered a planet orbiting within the “habitable zone” of its host star, a region where temperatures may allow liquid water to exist on the surface. Because water is essential for all known forms of life, this finding raises the possibility that the planet could have life-supporting conditions.
Located in a relatively nearby area of the Milky Way Galaxy,the planet appears to be rocky like Earth but several times more massive,earning it the classification of a “super-Earth.” The team of UC Irvine scientists and their collaborators describe their analysis of the planet in a new paper published in The Astronomical Journal.
“We have found so many exoplanets at this point that discovering a new one is not such a big deal,” said co-author paul Robertson, UC Irvine associate professor of physics & astronomy. “What makes this especially valuable is that its host star is close by, at just about 18 light-years away. Cosmically speaking, it’s practically next door.”
The planet, named GJ 251 c, orbits an M-dwarf star, which is the most common and oldest type of star in the Milky Way. Thes stars are known for strong stellar activity,including starspots (cool,dark regions on the star’s surface) and flares (sudden bursts of energy released into space). this activity can sometimes imitate the faint radial velocity (RV) signals that astronomers use to detect orbiting planets,potentially leading to false positives in exoplanet discovery.
Preparing for Future Observations
However, GJ 251 c’s proximity to Earth makes it an ideal target for future direct imaging studies with the University of California’s in-growth Thirty Meter Telescope.
The large size of TMT’s mirrors may enable it to directly image faint exoplanets like GJ 251 c and confirm the presence of water.
“TMT will be the only telescope with sufficient resolution to image exoplanets like this one. It’s just not possible with smaller telescopes,” said Corey Beard, Ph.D., data scientist at Design West Technologies, a former graduate student from Robertson’s group and the study’s lead author.
An international team of scientists dubbed the exoplanet, named GJ 251 c, a “super-Earth” as data suggest it has a rocky composition similar to Earth and is almost four times as massive. Credit: Illustration by University of California Irvine.
Potential habitable Super-Earth Discovered Near Our Solar System
Astronomers have identified a promising exoplanet candidate,GJ 251 c,orbiting a nearby star and potentially residing within the habitable zone. The discovery,detailed in a paper published October 23,2025,in The Astronomical Journal,was made possible through innovative analysis techniques and the High Precision Radial velocity Planet Searcher (HPF) instrument.
GJ 251 c orbits the M-dwarf star GJ 251, located relatively close to our solar system. M-dwarfs are smaller and cooler than our Sun, presenting challenges for planet detection due to their inherent stellar activity. Tho, the HPF instrument overcomes these hurdles by observing in the infrared spectrum, where stellar activity signals are less pronounced.
The research team, led by corey Beard and Paul Robertson, utilized computational modeling to achieve a statistically significant indication of the planet’s existence.While the findings are promising, the researchers emphasize the need for further confirmation through direct imaging.
“We are at the cutting edge of technology and analysis methods with this system,” said Beard. “While its discovery is quite statistically significant, we are still determining the status of the planet due to the uncertainty of our instruments and methods. we need the next generation of telescopes to directly image this candidate, but what we also need is community investment.”
The team hopes that their work will encourage further investigation of GJ 251 c, preparing the exoplanet science community for observations with powerful future telescopes like the Thirty Meter Telescope (TMT). Direct imaging would provide definitive proof of the planet’s existence and allow for detailed characterization of its atmosphere and potential habitability.
this research was supported by NSF grant AST-2108493 for the HPF exoplanet survey, as well as NASA/NSF and NASA ICAR program funding (grants 1716038 and 80NSSC23K1399 respectively).
Reference: Beard, C., Robertson, P., Lubin, J., et al. “Discovery of a Nearby Habitable Zone Super-Earth Candidate Amenable to direct Imaging.” The Astronomical Journal, 23 oct.2025, https://doi.org/10.3847/1538-3881/ae0e20.
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