Exoplanets & Exomoons

An Earth-sized Planet Around An M5 Dwarf Star At 22 Pc

By Keith Cowing
Status Report
February 2, 2023
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An Earth-sized Planet Around An M5 Dwarf Star At 22 Pc
Light curves of K2-415 obtained by K2 (top; K2SFF) and TESS (bottom; PDC-SAP). Those data were taken at long (≈ 29 minutes) and short (2 minutes) cadences for K2 and TESS light curves, respectively. The red solid line in each panel represents the GP regression to the observed light curve (see Section 4.4). — astro-ph.EP

We report on the discovery of an Earth-sized transiting planet (Rp=1.015±0.051R⊕) in a P=4.02 day orbit around K2-415 (EPIC 211414619), an M5V star at 22 pc.

The planet candidate was first identified by analyzing the light curve data by the K2 mission, and is here shown to exist in the most recent data from TESS. Combining the light curves with the data secured by our follow-up observations including high-resolution imaging and near infrared spectroscopy with IRD, we rule out false positive scenarios, finding a low false positive probability of 2×10−4.

Based on IRD’s radial velocities of K2-415, which were sparsely taken over three years, we obtain the planet mass of 3.0±2.7M⊕ (Mp<7.5M⊕ at 95% confidence) for K2-415b. Being one of the lowest mass stars (≈0.16M⊙) known to host an Earth-sized transiting planet, K2-415 will be an interesting target for further follow-up observations, including additional radial velocity monitoring and transit spectroscopy.

Teruyuki Hirano, Fei Dai, John H. Livingston, Yui Kasagi, Norio Narita, Hiroyuki Tako Ishikawa, Sascha Grziwa, Kristine W. F. Lam, Kohei Miyakawa, Luisa M. Serrano, Yuji Matsumoto, Eiichiro Kokubo, Tadahiro Kimura, Masahiro Ikoma, Joshua N. Winn, John P. Wisniewski, Hiroki Harakawa, Huan-Yu Teng, William D. Cochran, Akihiko Fukui, Davide Gandolfi, Eike W. Guenther, Yasunori Hori, Kai Ikuta, Kiyoe Kawauchi, Emil Knudstrup, Judith Korth, Takayuki Kotani, Vigneshwaran Krishnamurthy, Tomoyuki Kudo, Takashi Kurokawa, Masayuki Kuzuhara, Rafael Luque, Mayuko Mori, Jun Nishikawa, Masashi Omiya, Jaume Orell-Miquel, Enric Palle, Carina M. Persson, Seth Redfield, Eugene Serabyn, Alexis M. S. Smith, Aoi Takahashi, Takuya Takarada, Akitoshi Ueda, Vincent Van Eylen, Sebastien Vievard, Motohide Tamura, Bun’ei Sato

Comments: 20 pages, 12 figures, accepted for publication in AJ
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
Cite as: arXiv:2302.00699 [astro-ph.EP] (or arXiv:2302.00699v1 [astro-ph.EP] for this version)
Submission history
From: Hirano Teruyuki
[v1] Wed, 1 Feb 2023 19:00:29 UTC (3,984 KB)

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) 🖖🏻