GJ 367b: A dense, ultrashort-period sub-Earth planet transiting a nearby red dwarf star

Kristine W. F. Lam , Szilárd Csizmadia , Nicola Astudillo-Defru , Xavier Bonfils (1) , Davide Gandolfi , Sebastiano Padovan , Massimiliano Esposito , Coel Hellier , Teruyuki Hirano , John Livingston , Felipe Murgas , Alexis M. S. Smith , Karen A. Collins , Savita Mathur , Rafael A. Garcia , Steve B. Howell , Nuno C. Santos , Fei Dai , George R. Ricker , Roland Vanderspek , David W. Latham , Sara Seager , Joshua N. Winn , Jon M. Jenkins , Simon Albrecht , Jose M. Almenara (1) , Etienne Artigau (1) , Oscar Barragán , François Bouchy , Juan Cabrera (1) , David Charbonneau , Priyanka Chaturvedi , Alexander Chaushev , Jessie L. Christiansen , William D. Cochran , José R. de Meideiros , Xavier Delfosse (1) , Rodrigo F. Díaz , René Doyon , Philipp Eigmüller , Pedro Figueira , Thierry Forveille (1) , Malcolm Fridlund , Guillaume Gaisné (1) , Elisa Goffo , Iskra Georgieva , Sascha Grziwa , Eike Guenther , Artie P. Hatzes , Marshall C. Johnson , Petr Kabáth , Emil Knudstrup , Judith Korth , Pablo Lewin , Jack J. Lissauer , Christophe Lovis , Rafael Luque , Claudio Melo , Edward H. Morgan , Robert Morris , Michel Mayor , Norio Narita , Hannah L. M. Osborne , Enric Palle , Francesco Pepe , Carina M. Persson , Samuel N. Quinn , Heike Rauer , Seth Redfield , Joshua E. Schlieder , Damien Ségransan , Luisa M. Serrano , Jeffrey C. Smith , Ján Šubjak , Joseph D. Twicken , Stéphane Udry , Vincent van Eylen , Michael Vezie

1 IPAG - Institut de Planétologie et d'Astrophysique de Grenoble

Ultrashort-period (USP) exoplanets have orbital periods shorter than 1 day. Precise masses and radii of USP exoplanets could provide constraints on their unknown formation and evolution processes. We report the detection and characterization of the USP planet GJ 367b using high-precision photometry and radial velocity observations. GJ 367b orbits a bright (V-band magnitude of 10.2), nearby, and red (M-type) dwarf star every 7.7 hours. GJ 367b has a radius of 0.718 ± 0.054 Earth-radii and a mass of 0.546 ± 0.078 Earth-masses, making it a sub-Earth planet. The corresponding bulk density is 8.106 ± 2.165 grams per cubic centimeter—close to that of iron. An interior structure model predicts that the planet has an iron core radius fraction of 86 ± 5%, similar to that of Mercury’s interior.

Keywords: ASTRONOMY; PLANET SCI; Astrophysics - Earth and Planetary Astrophysics

Domains: Sciences of the Universe [physics]

Kristine W. F. Lam, Szilárd Csizmadia, Nicola Astudillo-Defru, Xavier Bonfils, Davide Gandolfi, et al.. GJ 367b: A dense, ultrashort-period sub-Earth planet transiting a nearby red dwarf star. Science, 2021, 374, pp.1271-1275. ⟨10.1126/science.aay3253⟩. ⟨insu-03705254⟩