Astronomers at the University of California – Irvine have identified a super-Earth, named GJ 251 c, located in the habitable zone of an M-dwarf star just 18 light-years from Earth. This discovery positions GJ 251 c as a significant target in the ongoing search for extraterrestrial life, particularly due to its potential to harbor liquid water, a key ingredient for life as we know it.
The planet’s rocky structure resembles that of Earth, but it is several times more massive, categorizing it as a super-Earth. According to co-author Paul Robertson, an associate professor of physics and astronomy at UC Irvine, the proximity of the star makes this discovery particularly valuable. “Cosmically speaking, it’s practically next door,” he noted. The team’s findings were detailed in a recent publication in The Astronomical Journal.
Examining a Planet Around an Active M-Dwarf Star
GJ 251 c orbits an M-dwarf star, known for being one of the oldest and most common types of stars in the Milky Way. M-dwarfs are often characterized by significant stellar activity, including starspots and flares, which can complicate the detection of orbiting planets. These stellar phenomena can mimic the subtle signals that astronomers look for when identifying new planets, making accurate detection challenging.
Despite these challenges, the close distance of GJ 251 c to Earth makes it a prime candidate for direct imaging using the Thirty Meter Telescope (TMT), which is currently under development. The advanced mirrors of the TMT are expected to allow astronomers to directly observe faint exoplanets like GJ 251 c, potentially revealing whether conditions on the planet could support water.
Corey Beard, a data scientist at Design West Technologies and lead author of the study, emphasized the significance of the TMT for imaging such distant worlds. “It’s just not possible with smaller telescopes,” he stated.
Cutting-Edge Instruments Uncover Subtle Signals
The research team leveraged data from the Habitable-zone Planet Finder (HPF) and NEID, two cutting-edge instruments specifically designed for exoplanet detection. These tools measure the gravitational effects that orbiting planets exert on their stars, leading to small, periodic shifts in starlight known as radial velocity signatures. By analyzing these shifts, astronomers confirmed the presence of GJ 251 c.
The HPF, in particular, is adept at minimizing the impact of M-dwarf stellar activity by observing in the infrared spectrum, where disruptive signals are weaker. The team’s computational analyses reached a statistical significance that supports the classification of GJ 251 c as a viable exoplanet candidate, reinforcing the need for direct imaging with the TMT to further investigate its properties.
Beard expressed optimism about the future of exoplanet exploration. “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,” he explained. He called for community investment in upcoming observational projects to explore GJ 251 c more thoroughly.
The collaborative research included contributions from experts such as Jack Lubin of UCLA, Eric Ford and Suvrath Mahadevan from Pennsylvania State University, Gudmundur Stefansson from the University of the Netherlands, and Eric Wolf from the University of Colorado, Boulder. Funding for this research was provided by the National Science Foundation (NSF) grant AST-2108493 for the HPF exoplanet survey, alongside support from NASA/NSF for the NN-EXPLORE program and NASA’s ICAR program.
As the scientific community awaits the operational status of next-generation telescopes, the findings on GJ 251 c stand as a promising development in the search for life beyond our planet.
