A Hot Mars-sized Exoplanet Transiting an M Dwarf

Caleb I. Caas, 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. RamseyPaul Robertson, Arpita Roy, Christian Schwab, Guđmundur Stefánsson

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


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.

Original languageEnglish (US)
Article number3
JournalAstronomical Journal
Issue number1
StatePublished - Jan 1 2022

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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