A hot Mars-sized exoplanet transiting an M dwarf

Caleb I. Cañas; Suvrath Mahadevan; William D. Cochran; Chad F. Bender; Eric D. Feigelson; C. E. Harman; Ravi Kumar Kopparapu; Gabriel A. Caceres; Scott A. Diddams; Michael Endl; Eric B. Ford; Samuel Halverson; Fred Hearty; Sinclaire Jones; Shubham Kanodia; Andrea S. J. Lin; Andrew J. Metcalf; Andrew Monson; Joe P. Ninan; Lawrence W. Ramsey; Paul Robertson; Arpita Roy; Christian Schwab; Guðmundur Stefánsson

doi:10.3847/1538-3881/ac3088

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arXiv · 2112.03958

A hot Mars-sized exoplanet transiting an M dwarf

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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 ($\mathrm{R}_{p}=0.51 \pm 0.03R_{\oplus}$) orbiting the host star every 0.412-days ($\sim9.9$-hours). 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 $3\sigma$ mass to $M_{p}<0.34~\mathrm{M_\oplus}$ by assuming the planet is less dense than iron. Obtaining a mass measurement for KOI-4777.01 is beyond current instrumental capabilities.

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Caleb I. Cañas, Suvrath Mahadevan, William D. Cochran, Chad F. Bender, Eric D. Feigelson, C. E. Harman, Ravi Kumar Kopparapu, Gabriel A. Caceres, Scott A. Diddams, Michael Endl, Eric B. Ford, Samuel Halverson, Fred Hearty, Sinclaire Jones, Shubham Kanodia, Andrea S. J. Lin, Andrew J. Metcalf, Andrew Monson, Joe P. Ninan, Lawrence W. Ramsey, Paul Robertson, Arpita Roy, Christian Schwab, Guðmundur Stefánsson. 2021-12-07. A hot Mars-sized exoplanet transiting an M dwarf. https://doi.org/10.3847/1538-3881%2Fac3088

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