A Hot Mars-sized Exoplanet Transiting an M Dwarf
Cochran, William D.; Endl, Michael; Mahadevan, Suvrath; Feigelson, Eric D.; Ford, Eric B.; Monson, Andrew; Cañas, Caleb I.; Kanodia, Shubham; Ninan, Joe P.; Bender, Chad F.; Diddams, Scott A.; Halverson, Samuel; Hearty, Fred; Metcalf, Andrew J.; Ramsey, Lawrence W.; Robertson, Paul; Roy, Arpita; Schwab, Christian; Lin, Andrea S. J.; Stefánsson, Guđmundur; Harman, C. E.; Kopparapu, Ravi Kumar; Jones, Sinclaire; Caceres, Gabriel A.
United States, Australia
Abstract
We validate the planetary nature of an ultra-short-period planet orbiting the M dwarf KOI-4777. We use a combination of space-based photometry from Kepler, high-precision, near-infrared Doppler spectroscopy from the Habitable-zone Planet Finder, and adaptive optics imaging to characterize this system. KOI-4777.01 is a Mars-sized exoplanet (R p = 0.51 ± 0.03R ⊕) orbiting the host star every 0.412 days (~9.9 hr). This is the smallest validated ultra-short period planet known and we see no evidence for additional massive companions using our HPF RVs. We constrain the upper 3σ mass to M p < 0.34 M ⊕ by assuming the planet is less dense than iron. Obtaining a mass measurement for KOI-4777.01 is beyond current instrumental capabilities.