Astronomers Discover Potentially Habitable “Super-Earth” Just 18 Light-Years Away

The team discovered that the surface might contain liquid water, an essential ingredient for life.

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. These 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-development 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.

The discovery of GJ 251 c was made possible by data from the Habitable-zone Planet Finder and NEID – exoplanet-hunting instruments Robertson helped build. HPF and NEID detect the subtle effects an orbiting exoplanet has on its host star.

As GJ 251 c’s gravity pulls on its host star, it creates small, rhythmic shifts in the star’s emitted light. HPF recorded these subtle shifts in light, which, known as radial velocity signatures, were used to determine the existence of the orbiting exoplanet.

HPF helps overcome some of M-dwarf’s stellar activity issues by observing the night sky in the infrared – a part of the spectrum where stellar activity signals are weaker.

Next Steps and the Future of Exoplanet Research

The statistical significance of the team’s computational modeling work is strong enough to identify GJ 251 c as an exoplanet candidate, emphasizing the importance of future direct imaging observations with TMT.

“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.”

Beard and Robertson hope that their work can motivate the exoplanet science community to further investigate GJ 251 c in preparation for the direct imaging capabilities of next-generation ground-based observatories like Thirty Meter Telescope.

Reference: “Discovery of a Nearby Habitable Zone Super-Earth Candidate Amenable to Direct Imaging” by Corey Beard, Paul Robertson, Jack Lubin, Eric B. Ford, Suvrath Mahadevan, Gudmundur Stefansson, Jason T. Wright, Eric Wolf, Vincent Kofman, Vidya Venkatesan, Ravi Kopparapu, Roan Arendtsz, Rae Holcomb, Raquel A. Martinez, Stephanie Sallum, Jacob K. Luhn, Chad F. Bender, Cullen H. Blake, William D. Cochran, Megan Delamer, Scott A. Diddams, Michael Endl, Samuel Halverson, Shubham Kanodia, Daniel M. Krolikowski, Andrea S. J. Lin, Sarah E. Logsdon, Michael W. McElwain, Andrew Monson, Joe P. Ninan, Jayadev Rajagopal, Arpita Roy, Christian Schwab and Ryan C. Terrien, 23 October 2025, The Astronomical Journal.
DOI: 10.3847/1538-3881/ae0e20

The work was supported by NSF grant AST-2108493 for the HPF exoplanet survey and NASA/NSF funding for NN-EXPLORE program (grant number: 1716038); NASA ICAR program 80NSSC23K1399.

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