Planetary system around the nearby M dwarf GJ 357 including a transiting, hot, Earth-sized planet optimal for atmospheric characterization

Publication date: 
Main author: 
Luque, R.
IAA authors: 
Anglada-Escudé, G.;Rodríguez-López, C.;Amado, P. J.;Bauer, F. F.
Luque, R.;Pallé, E.;Kossakowski, D.;Dreizler, S.;Kemmer, J.;Espinoza, N.;Burt, J.;Anglada-Escudé, G.;Béjar, V. J. S.;Caballero, J. A.;Collins, K. A.;Collins, K. I.;Cortés-Contreras, M.;Díez-Alonso, E.;Feng, F.;Hatzes, A.;Hellier, C.;Henning, T.;Jeffers, S. V.;Kaltenegger, L.;Kürster, M.;Madden, J.;Molaverdikhani, K.;Montes, D.;Narita, N.;Nowak, G.;Ofir, A.;Oshagh, M.;Parviainen, H.;Quirrenbach, A.;Reffert, S.;Reiners, A.;Rodríguez-López, C.;Schlecker, M.;Stock, S.;Trifonov, T.;Winn, J. N.;Zapatero Osorio, M. R.;Zechmeister, M.;Amado, P. J.;Anderson, D. R.;Batalha, N. E.;Bauer, F. F.;Bluhm, P.;Burke, C. J.;Butler, R. P.;Caldwell, D. A.;Chen, G.;Crane, J. D.;Dragomir, D.;Dressing, C. D.;Dynes, S.;Jenkins, J. M.;Kaminski, A.;Klahr, H.;Kotani, T.;Lafarga, M.;Latham, D. W.;Lewin, P.;McDermott, S.;Montañés-Rodríguez, P.;Morales, J. C.;Murgas, F.;Nagel, E.;Pedraz, S.;Ribas, I.;Ricker, G. R.;Rowden, P.;Seager, S.;Shectman, S. A.;Tamura, M.;Teske, J.;Twicken, J. D.;Vanderspeck, R.;Wang, S. X.;Wohler, B.
Astronomy and Astrophysics
Publication type: 
We report the detection of a transiting Earth-size planet around GJ 357, a nearby M2.5 V star, using data from the Transiting Exoplanet Survey Satellite (TESS). GJ 357 b (TOI-562.01) is a transiting, hot, Earth-sized planet (T<SUB>eq</SUB> = 525 ± 11 K) with a radius of R<SUB>b</SUB> = 1.217 ± 0.084 R<SUB>⊕</SUB> and an orbital period of P<SUB>b</SUB> = 3.93 d. Precise stellar radial velocities from CARMENES and PFS, as well as archival data from HIRES, UVES, and HARPS also display a 3.93-day periodicity, confirming the planetary nature and leading to a planetary mass of M<SUB>b</SUB> = 1.84 ± 0.31 M<SUB>⊕</SUB>. In addition to the radial velocity signal for GJ 357 b, more periodicities are present in the data indicating the presence of two further planets in the system: GJ 357 c, with a minimum mass of M<SUB>c</SUB> = 3.40 ± 0.46 M<SUB>⊕</SUB> in a 9.12 d orbit, and GJ 357 d, with a minimum mass of M<SUB>d</SUB> = 6.1 ± 1.0 M<SUB>⊕</SUB> in a 55.7 d orbit inside the habitable zone. The host is relatively inactive and exhibits a photometric rotation period of P<SUB>rot</SUB> = 78 ± 2 d. GJ 357 b isto date the second closest transiting planet to the Sun, making it a prime target for further investigations such as transmission spectroscopy. Therefore, GJ 357 b represents one of the best terrestrial planets suitable for atmospheric characterization with the upcoming JWST and ground-based ELTs. RV data are only available at the CDS via anonymous ftp to <A href=''></A> ( or via <A href=''></A>
ADS Bibcode: 
planetary systems;techniques: photometric;techniques: radial velocities;stars: individual: Gl 357;stars: late-type;Astrophysics - Earth and Planetary Astrophysics