@article{f7fbaa83a39b4bbfae1ee84ffb5017b4,
title = "An Earth-sized Planet around an M5 Dwarf Star at 22 pc",
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{\textquoteright}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.",
author = "Teruyuki Hirano and Fei Dai and Livingston, {John H.} and Sascha Grziwa and Lam, {Kristine W.F.} and Yui Kasagi and Norio Narita and Ishikawa, {Hiroyuki Tako} and Kohei Miyakawa and Serrano, {Luisa M.} and Yuji Matsumoto and Eiichiro Kokubo and Tadahiro Kimura and Masahiro Ikoma and Winn, {Joshua N.} and Wisniewski, {John P.} and Hiroki Harakawa and Teng, {Huan Yu} and Cochran, {William D.} and Akihiko Fukui and Davide Gandolfi and Guenther, {Eike W.} and Yasunori Hori and Kai Ikuta and Kiyoe Kawauchi and Emil Knudstrup and Judith Korth and Takayuki Kotani and Vigneshwaran Krishnamurthy and Tomoyuki Kudo and Takashi Kurokawa and Masayuki Kuzuhara and Rafael Luque and Mayuko Mori and Jun Nishikawa and Masashi Omiya and Jaume Orell-Miquel and Enric Palle and Persson, {Carina M.} and Seth Redfield and Eugene Serabyn and Smith, {Alexis M.S.} and Aoi Takahashi and Takuya Takarada and Akitoshi Ueda and {Van Eylen}, Vincent and S{\'e}bastien Vievard and Motohide Tamura and Bun{\textquoteright}ei Sato",
note = "Funding Information: We thank the anonymous referee for the insightful comments to improve the manuscript. This work was supported by JSPS KAKENHI grant Nos. JP19K14783, JP21H00035, JP18H05442, JP15H02063, JP22000005, JP18H05438, JP21K20388, and JP18H05439, and JST CREST grant No. JPMJCR1761. K.W.F.L. was supported by Deutsche Forschungsgemeinschaft grants RA714/14-1 within the DFG Schwerpunkt SPP 1992, Exploring the Diversity of Extrasolar Planets. R.L. acknowledges funding from University of La Laguna through the Margarita Salas Fellowship from the Spanish Ministry of Universities ref. UNI/551/2021-May 26, and under the EU Next Generation funds. J.K. gratefully acknowledges the support of the Swedish National Space Agency (SNSA; DNR 2020-00104). We are grateful to Noriharu Watanabe, Taiki Kagetani, and Yujie Zou for the support of IRD observations. We also thank Kento Masuda for the helpful discussion on rotation periods of mid-M dwarfs. This work was supported by the KESPRINT collaboration, an international consortium devoted to the characterization and research of exoplanets discovered with space-based missions (https://kesprint.science/). This research is based in part on data collected at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan. The data analysis was carried out, in part, on the Multi-wavelength Data Analysis System operated by the Astronomy Data Center (ADC), National Astronomical Observatory of Japan. Part of this work was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. We are honored and grateful for the opportunity of observing the Universe from Maunakea, which has cultural, historical, and natural significance in Hawaii. Funding Information: We thank the anonymous referee for the insightful comments to improve the manuscript. This work was supported by JSPS KAKENHI grant Nos. JP19K14783, JP21H00035, JP18H05442, JP15H02063, JP22000005, JP18H05438, JP21K20388, and JP18H05439, and JST CREST grant No. JPMJCR1761. K.W.F.L. was supported by Deutsche Forschungsgemeinschaft grants RA714/14-1 within the DFG Schwerpunkt SPP 1992, Exploring the Diversity of Extrasolar Planets. R.L. acknowledges funding from University of La Laguna through the Margarita Salas Fellowship from the Spanish Ministry of Universities ref. UNI/551/2021-May 26, and under the EU Next Generation funds. J.K. gratefully acknowledges the support of the Swedish National Space Agency (SNSA; DNR 2020-00104). We are grateful to Noriharu Watanabe, Taiki Kagetani, and Yujie Zou for the support of IRD observations. We also thank Kento Masuda for the helpful discussion on rotation periods of mid-M dwarfs. This work was supported by the KESPRINT collaboration, an international consortium devoted to the characterization and research of exoplanets discovered with space-based missions ( https://kesprint.science/ ). This research is based in part on data collected at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan. The data analysis was carried out, in part, on the Multi-wavelength Data Analysis System operated by the Astronomy Data Center (ADC), National Astronomical Observatory of Japan. Part of this work was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. We are honored and grateful for the opportunity of observing the Universe from Maunakea, which has cultural, historical, and natural significance in Hawaii. Publisher Copyright: {\textcopyright} 2023. The Author(s). Published by the American Astronomical Society.",
year = "2023",
month = mar,
day = "1",
doi = "10.3847/1538-3881/acb7e1",
language = "English (US)",
volume = "165",
journal = "Astronomical Journal",
issn = "0004-6256",
publisher = "IOP Publishing Ltd.",
number = "3",
}