Discovery of a hot, transiting, Earth-sized planet and a second temperate, non-transiting planet around the M4 dwarf GJ 3473 (TOI-488)
J. Kemmer, S. Stock, D. Kossakowski, A. Kaminski, K. Molaverdikhani, M. Schlecker, J. A. Caballero, P. J. Amado, N. Astudillo-Defru, X. Bonfils, D. Ciardi, K. A. Collins, N. Espinoza, A. Fukui, T. Hirano, J. M. Jenkins, D. W. Latham, E. C. Matthews, N. Narita, E. Pallé, H. Parviainen, A. Quirrenbach, A. Reiners, I. Ribas, G. Ricker, J. E. Schlieder, S. Seager, R. Vanderspek, J. N. Winn, J. M. Almenara, V. J. S. Béjar, P. Bluhm, F. Bouchy, P. Boyd, J. L. Christiansen, C. Cifuentes, R. Cloutier, K. I. Collins, M. Cortés-Contreras, I. J M. Crossfield, N. Crouzet, J. P. de Leon, D. D. Della-Rose, X. Delfosse, S. Dreizler, E. Esparza-Borges, Z. Essack, Th. Forveille, P. Figueira, D. Galadí-Enríquez, T. Gan, A. Glidden, E. J. Gonzales, P. Guerra, H. Harakawa, A. P. Hatzes, Th. Henning, E. Herrero, K. Hodapp, Y. Hori, S. B. Howell, M. Ikoma, K. Isogai, S. V. Jeffers, M. Kürster, K. Kawauchi, T. Kimura, P. Klagyivik, T. Kotani, T. Kurokawa, N. Kusakabe, M. Kuzuhara, M. Lafarga, J. H. Livingston, R. Luque, R. Matson, J. C. Morales, M. Mori, P. S. Muirhead, F. Murgas, J. Nishikawa, T. Nishiumi, M. Omiya, S. Reffert, C. Rodríguez López, N. C. Santos, P. Schöfer, R. P. Schwarz, B. Shiao, M. Tamura, Y. Terada, J. D. Twicken, A. Ueda, S. Vievard, N. Watanabe, M. Zechmeister
Abstract
We present the confirmation and characterisation of GJ 3473 b (G 50–16, TOI-488.01), a hot Earth-sized planet orbiting an M4 dwarf star, whose transiting signal ( P = 1.1980035 ± 0.0000018 d) was first detected by the Transiting Exoplanet Survey Satellite (TESS). Through a joint modelling of follow-up radial velocity observations with CARMENES, IRD, and HARPS together with extensive ground-based photometric follow-up observations with LCOGT, MuSCAT, and MuSCAT2, we determined a precise planetary mass, M b = 1.86 ± 0.30 M ⊕ , and radius, R b = 1.264 ± 0.050 R ⊕ . Additionally, we report the discovery of a second, temperate, non-transiting planet in the system, GJ 3473 c, which has a minimum mass, M c sin i = 7.41 ± 0.91 M ⊕ , and orbital period, P c = 15.509 ± 0.033 d. The inner planet of the system, GJ 3473 b, is one of the hottest transiting Earth-sized planets known thus far, accompanied by a dynamical mass measurement, which makes it a particularly attractive target for thermal emission spectroscopy.