CaltechAUTHORS
Published March 2023 | Version Published
Journal Article Open

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

Creators

  • 1. ROR icon Astrobiology Center
  • 2. ROR icon National Astronomical Observatory of Japan
  • 3. ROR icon The Graduate University for Advanced Studies, SOKENDAI
  • 4. ROR icon California Institute of Technology
  • 5. ROR icon University of Cologne
  • 6. ROR icon German Aerospace Center
  • 7. ROR icon University of Tokyo
  • 8. ROR icon Instituto de Astrofísica de Canarias
  • 9. ROR icon University of Turin
  • 10. ROR icon Princeton University
  • 11. ROR icon George Mason University
  • 12. ROR icon University of Hawaii at Hilo
  • 13. ROR icon The University of Texas at Austin
  • 14. ROR icon Thüringer Landessternwarte Tautenburg
  • 15. ROR icon Aarhus University
  • 16. ROR icon Chalmers University of Technology
  • 17. ROR icon Tokyo University of Agriculture and Technology
  • 18. ROR icon University of Chicago
  • 19. ROR icon University of La Laguna
  • 20. ROR icon Wesleyan University
  • 21. ROR icon Jet Propulsion Lab
  • 22. ROR icon University College London

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.

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. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. 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. Facilities: Subaru (IRD - , IRCS) - , WIYN (NESSI) - . Software: vespa (Morton 2015), TRICERATOPS (Giacalone et al. 2021).

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Additional details

Identifiers

Eprint ID
120374
Resolver ID
CaltechAUTHORS:20230323-483768400.11

Funding

Japan Society for the Promotion of Science (JSPS)
JP19K14783
Japan Society for the Promotion of Science (JSPS)
JP21H00035
Japan Society for the Promotion of Science (JSPS)
JP18H05442
Japan Society for the Promotion of Science (JSPS)
JP15H02063
Japan Society for the Promotion of Science (JSPS)
JP22000005
Japan Society for the Promotion of Science (JSPS)
JP18H05438
Japan Society for the Promotion of Science (JSPS)
JP21K20388
Japan Society for the Promotion of Science (JSPS)
JP18H05439
Japan Science and Technology Agency
JPMJCR1761
Deutsche Forschungsgemeinschaft (DFG)
RA714/14-1
Deutsche Forschungsgemeinschaft (DFG)
SPP 1992
Ministerio de Universidades
UNI/551/2021-May 26
Swedish National Space Agency
DNR 2020-00104
KESPRINT Collaboration
National Astronomical Observatory of Japan
NASA/JPL/Caltech
NASA Sagan Fellowship

Dates

Created
2023-05-05
Created from EPrint's datestamp field
Updated
2023-05-05
Created from EPrint's last_modified field