Paper

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

Kemmer, J, Montes, D, Klahr, H, Zapatero Osorio, M R, Nagel, E, Bluhm, P, Lafarga, M, Ribas, I, Collins, K A, Jenkins, J M, McDermott, S, Tamura, M, Rowden, P, Bauer, F F, Butler, R P, Ricker, G R, Dreizler, S, Collins, K I, Trifonov, T, Quirrenbach, A, Latham, D W, Rodríguez-López, C, Espinoza, N, Dynes, S, Caballero, J A, Winn, J N, Kaminski, A, Narita, N, Kossakowski, D, Seager, S, Shectman, S A, Kotani, T, Hatzes, A, Anglada-Escudé, G, Jeffers, S V, Burt, J, Zechmeister, M, Pedraz, S, Parviainen, H, Amado, P J, Montañés-Rodríguez, P, Stock, S, Dressing, C D, Wang, S X, Oshagh, M, Morales, J C, Murgas, F, Vanderspeck, R, Molaverdikhani, K, Anderson, D R, Pallé, E, Henning, T, Kaltenegger, L, Chen, G, Dragomir, D, Lewin, P, Béjar, V J S, Luque, R, Kürster, M, Madden, J, Reffert, S, Schlecker, M, Burke, C J, Hellier, C, Twicken, J D, Feng, F, Cortés-Contreras, M, Batalha, N E, Crane, J D, Caldwell, D A, Nowak, G, Ofir, A, Reiners, A, Teske, J, Díez-Alonso, E, Wohler, B

2019

Overview

We report the detection of a transiting Earth-size planet around GJ 357, a nearby M2.5V star, using data from the Transiting Exoplanet Survey Satellite (TESS). GJ 357 b (TOI-562.01) is a transiting, hot, Earth-sized planet (Teq=525+-11 K) with a radius of Rb=1.217+-0.084 Re and an orbital period of Pb=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 Mb=1.84+-0.31 Me. 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 Mc=3.40+-0.46 Me in a 9.12 d orbit, and GJ 357 d, with a minimum mass of Md=6.1+-1.0 Me in a 55.7 d orbit inside the habitable zone. The host is relatively inactive and exhibits a photometric rotation period of Prot=78+-2 d. GJ 357 b is to 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.

• Publisher: Cornell University Library, arXiv.org
• Subject: Earth / Extrasolar planets / Orbits / Periodic variations / Photometry / Planet detection / Planetary mass / Planetary systems / Radial velocity / Transit