Super-Earth discovered near habitable zone offers strong potential for finding alien life
Researchers have identified GJ 251 c, a possible "super-Earth" nearly four times the mass of Earth, located less than 20 light-years away in its star's habitable zone. The discovery, based on two decades of observational data using the Habitable-Zone Planet Finder (HPF), marks one of the strongest opportunities yet to search for atmospheric signatures of life using next-generation telescopes.
A possible "super-Earth" located less than 20 light-years from Earth is fueling renewed optimism among researchers in the search for planets that might host life. The newly identified world, GJ 251 c, earned its "super-Earth" label because current data indicate it is almost four times the mass of Earth and is likely a rocky planet.
"We look for these types of planets because they are our best chance at finding life elsewhere," said Suvrath Mahadevan, the Verne M. Willaman Professor of Astronomy at Penn State and co-author of a recent paper in The Astronomical Journal. He confirmed that the exoplanet is located in the habitable or "Goldilocks Zone," meaning it is the right distance from its star that liquid water could exist on its surface, provided it has the correct atmosphere.
Two Decades of Observations Lead to Breakthrough
This significant result arose from more than 20 years of observations, representing one of the strongest opportunities yet to investigate a potentially habitable world. The exoplanet was identified using data from the Habitable-Zone Planet Finder (HPF), a high-precision near-infrared spectrograph designed to separate starlight into its component colors. The HPF is installed on the Hobby-Eberly Telescope at the McDonald Observatory in Texas.
Mahadevan and his team studied a large set of measurements collected worldwide over two decades. Their analysis focused on the small, measurable "wobble" of the host star, GJ 251, caused by the gravitational pulls from orbiting planets, which appears as slight Doppler shifts in the star's light.
By combining long-term observations with new high-precision HPF data, the researchers detected a strong signal repeating every 54 days, pointing to the presence of the more massive second planet. This discovery was subsequently confirmed by the NEID spectrometer at the Kitt Peak National Observatory in Arizona.
Overcoming Challenges and Looking Ahead
One of the major difficulties was separating the planet's subtle signal from the star's own magnetic activity—a form of "stellar weather" that can mimic planetary variations. The team used advanced modeling techniques to distinguish between the two.
"This discovery represents one of the best candidates in the search for atmospheric signature of life elsewhere in the next five to ten years," Mahadevan said.
Although current technology cannot produce direct images of GJ 251 c, Mahadevan noted that upcoming telescopes will be capable of examining the planet's atmosphere, potentially revealing chemical traces of life. The planet is situated in an optimal position for future advanced telescopes, and Mahadevan and his students are already preparing for the era of 30-meter-class ground-based telescopes, which will carry instruments capable of imaging rocky planets within their stars' habitable zones.
