Newly Discovered Exoplanet Could Be an Earth-Sized Sea of Volcanoes

The growing catalog of exoplanets has seen only a few directly imaged. This is primarily due to their small size and dimness compared to the stars they orbit. Therefore, we typically infer the existence of exoplanets through methods such as gravity (radial velocity) or changes in the star’s brightness (transit photometry). The latter approach, which involves tracking dips in brightness as planets pass in front of their host stars, has proven most successful in exoplanet hunting. It is how the team identified LP 791-18 d, situated 86 light-years away. The data confirming its presence around the star LP 791-18 came from NASA’s Transiting Exoplanet Survey Satellite, the retired (but potentially reactivated) Spitzer Space Telescope, and ground-based observatories.

The researchers speculate that LP 791-18 d is volcanically active, although this conclusion is based solely on its orbital characteristics. What distinguishes this newly discovered exoplanet is its companions within the three-planet system revolving around its low-mass star. The closer exoplanet is 20% larger than Earth, while the outer world is a whopping 250% larger (depicted as the blue dot in the image above). The constant gravitational interactions within the system have prevented LP 791-18 d from achieving a fully circular orbit. Consequently, the team suggests that tidal heating resulting from these interactions likely triggers widespread volcanic activity on the planet’s surface.