Exoplanets & Exomoons

EPIC 228813918 b: An Earth-sized Planet in a 4.3-hour Orbit Around An M-dwarf

By Keith Cowing
Press Release
August 2, 2017
Filed under
EPIC 228813918 b: An Earth-sized Planet in a 4.3-hour Orbit Around An M-dwarf

We report the discovery from K2 of a transiting terrestrial planet in an ultra-short-period orbit around an M3-dwarf.

EPIC 228813918 b completes an orbit in only 4.3 hours, the second-shortest orbital period of any known planet, just 4 minutes longer than that of KOI 1843.03, which also orbits an M-dwarf. Using a combination of archival images, AO imaging, RV measurements, and light curve modelling, we show that no plausible eclipsing binary scenario can explain the K2 light curve, and thus confirm the planetary nature of the system. The planet, whose radius we determine to be 0.89 +/- 0.09 Earth radii, and which must have a iron mass fraction greater than 0.45, orbits a star of mass 0.463 +/- 0.052 Msol and radius 0.442 +/- 0.044 Rsol.

A. M. S. Smith, J. Cabrera, Sz. Csizmadia, F. Dai, D. Gandolfi, T. Hirano, J. N. Winn, S. Albrecht, R. Alonso, G. Antoniciello, O. Barragán, H. Deeg, Ph. Eigmüller, M. Endl, A. Erikson, M. Fridlund, A. Fukui, S. Grziwa, E. W. Guenther, A. P. Hatzes, D. Hidalgo, A. W. Howard, H. Isaacson, J. Korth, M. Kuzuhara, J. Livingston, N. Narita, D. Nespral, G. Nowak, E. Palle, M. Pätzold, C.M. Persson, E. Petigura, J. Prieto-Arranz, H. Rauer, I. Ribas, V. Van Eylen
(Submitted on 14 Jul 2017)

Comments: 12 pages, 9 figures, submitted to MNRAS
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:1707.04549 [astro-ph.EP] (or arXiv:1707.04549v1 [astro-ph.EP] for this version)
Submission history
From: Alexis Smith
[v1] Fri, 14 Jul 2017 15:53:58 GMT (946kb,D)

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻