Planetary system around the nearby M dwarf GJ 357 including a transiting, hot, Earth-sized planet optimal for atmospheric characterization
Tamura, M.; Nagel, E.; Amado, P. J.; Bauer, F. F.; Caballero, J. A.; Pallé, E.; Reiners, A.; Ribas, I.; Quirrenbach, A.; Anglada-Escudé, G.; Béjar, V. J. S.; Henning, T.; Kaminski, A.; Kürster, M.; Montes, D.; Morales, J. C.; Zapatero Osorio, M. R.; Zechmeister, M.; Cortés-Contreras, M.; Dreizler, S.; Jeffers, S. V.; Lafarga, M.; Narita, N.; Burt, J.; Butler, R. P.; Crane, J. D.; Nowak, G.; Winn, J. N.; Kaltenegger, L.; Rowden, P.; Collins, K. A.; Collins, K. I.; Jenkins, J. M.; Luque, R.; Ricker, G. R.; Seager, S.; Twicken, J. D.; Oshagh, M.; Rodríguez-López, C.; Chen, G.; Molaverdikhani, K.; Latham, D. W.; Burke, C. J.; Murgas, F.; Anderson, D. R.; Hellier, C.; Parviainen, H.; Stock, S.; Kemmer, J.; Schlecker, M.; Reffert, S.; Espinoza, N.; Kossakowski, D.; Bluhm, P.; Trifonov, T.; Wohler, B.; Hatzes, A.; Ofir, A.; Caldwell, D. A.; Pedraz, S.; Dressing, C. D.; Dragomir, D.; Wang, S. X.; Batalha, N. E.; Teske, J.; Kotani, T.; Feng, F.; Díez-Alonso, E.; Klahr, H.; Montañés-Rodríguez, P.; Shectman, S. A.; Lewin, P.; Madden, J.; Dynes, S.; McDermott, S.; Vanderspeck, R.
Spain, Germany, United States, United Kingdom, Japan, Israel, China
Abstract
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 (Teq = 525 ± 11 K) with a radius of Rb = 1.217 ± 0.084 R⊕ 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 M⊕. 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 M⊕ in a 9.12 d orbit, and GJ 357 d, with a minimum mass of Md = 6.1 ± 1.0 M⊕ 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 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 http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/628/A39