e-Article
An Earth-sized Planet around an M5 Dwarf Star at 22 pc
Document Type
article
Author
Teruyuki Hirano; Fei Dai; John H. Livingston; Sascha Grziwa; Kristine W. F. Lam; Yui Kasagi; Norio Narita; Hiroyuki Tako Ishikawa; 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; Sébastien Vievard; Motohide Tamura; Bun’ei Sato
Source
The Astronomical Journal, Vol 165, Iss 3, p 131 (2023)
Subject
Language
English
ISSN
1538-3881
Abstract
We report on the discovery of an Earth-sized transiting planet ( R _p = 1.015 ± 0.051 R _⊕ ) 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 obtained by the K2 mission, and it 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 a planet mass of 3.0 ± 2.7 M _⊕ ( M _p < 7.5 M _⊕ at 95% confidence) for K2-415b. Being one of the lowest-mass stars (≈0.16 M _⊙ ) 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.