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An Earth-sized Planet around an M5 Dwarf Star at 22 pc

Hirano, T; Dai, F; Livingston, JH; Grziwa, S; Lam, KWF; Kasagi, Y; Narita, N; ... Sato, B; + view all (2023) An Earth-sized Planet around an M5 Dwarf Star at 22 pc. The Astronomical Journal , 165 (3) , Article 131. 10.3847/1538-3881/acb7e1. Green open access

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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.

Type: Article
Title: An Earth-sized Planet around an M5 Dwarf Star at 22 pc
Open access status: An open access version is available from UCL Discovery
DOI: 10.3847/1538-3881/acb7e1
Publisher version: https://doi.org/10.3847/1538-3881/acb7e1
Language: English
Additional information: © 2023. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence (http://creativecommons.org/licenses/by/4.0/). Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
Keywords: Transit photometry (1709); High angular resolution (2167); Highresolution spectroscopy (2096); Exoplanet formation (492); Radial velocity (1332)
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Space and Climate Physics
URI: https://discovery.ucl.ac.uk/id/eprint/10166839
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