February 25, 2021 Poster Open Access

A Terrestrial-mass Planet Orbiting GJ 1151: The Possible Source of Coherent Low-frequency Radio Emission from an Inactive Star

Stefansson, Gudmundur; Mahadevan, Suvrath; Robertson, Paul; Terrien, Ryan; Ninan, Joe; Holcomb, Rae; Halverson, Samuel; Cochran, William; Kanodia, Shubham; Ramsey, Lawrence; Wolszczan, Alexander; Endl, Michael; Bender, Chad; Diddams, Scott; Frederick, Connor; Hearty, Frederick; Monson, Andrew; Metcalf, Andrew; Roy, Arpita; Schwab, Christian

The coherent low-frequency radio emission detected by LOFAR from the quiescent M4.5 dwarf star GJ 1151 is consistent with theoretical expectations of star-planet interactions for an Earth-sized planet on a 1-5 day orbit. Using precise near-infrared radial velocities (RVs) with the Habitable-zone Planet Finder (HPF) on the 10m Hobby-Eberly Telescope at McDonald Observatory along with literature RVs from HARPS-N, we reveal a periodic Doppler signature consistent with a 2.5 Earth mass planet in a 2.02-day orbit. Precise photometry from the Transiting Exoplanet Survey Satellite (TESS) shows no flares or activity signature, consistent with a quiescent M dwarf. While no planetary transit is detected in the TESS data, a weak photometric modulation is detectable in the photometry at a ~2 day period. This independent detection of a planet signal with the RV technique adds further weight to the claim to one of the first detection of star-exoplanet interactions at radio wavelengths, and helps validate this emerging technique for the detection of exoplanets.