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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. 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. R. Ricker, J. E. Schlieder, S. Seager, R. K. Vanderspek, J. N. Winn, J.-M. Almenara, V. J. Sánchez 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. de Leon, D. D. Della-Rose, X. Delfosse, S. Dreizler, E. Esparza-Borges, Z. Essack, T. Forveille, P. Figueira, D. Galadí-Enríquez, T. Gan, A. Glidden, E. J. Gonzales, P. Guerra, H. Harakawa, A. Hatzes, T. Henning, E. Herrero, K. W. 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. A. 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

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, Mb = 1.86 ± 0.30 M, and radius, Rb = 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, Mc sin i = 7.41 ± 0.91 M, and orbital period, Pc = 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.

planetary systems; planets and satellites: detection; techniques: radial velocities; techniques: photometric; stars: late-type; stars: individual: G 50-16; Astrophysics - Earth and Planetary Astrophysics

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Astronomy and Astrophysics
Volume 642, Article Number A236, Number of pages 20
2020 October

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Instituto de Astrofísica e Ciências do Espaço Universidade do Porto Faculdade de Ciências da Universidade de Lisboa
Fundação para a Ciência e a Tecnologia COMPETE 2020 PORTUGAL 2020 União Europeia