TOI-1201 b: A mini-Neptune transiting a bright and moderately young M dwarf
Amado, P. J.; Caballero, J. A.; Pallé, E.; Reiners, A.; Ribas, I.; Quirrenbach, A.; Béjar, V. J. S.; Kaminski, A.; Kürster, M.; Montes, D.; Morales, J. C.; Zapatero Osorio, M. R.; Zechmeister, M.; Schweitzer, A.; Cortés-Contreras, M.; Dreizler, S.; Jeffers, S. V.; Lafarga, M.; Nowak, G.; Henning, Th.; Galadí-Enríquez, D.; Collins, K. A.; Conti, D. M.; Jenkins, J. M.; Luque, R.; Seager, S.; Lillo-Box, J.; Oshagh, M.; Molaverdikhani, K.; Latham, D. W.; Ricker, G.; Vanderspek, R.; Winn, J.; Morello, G.; Anderson, D. R.; Hellier, C.; Lodieu, N.; Stock, S.; Herrero, E.; Vanaverbeke, S.; Kemmer, J.; Schlecker, M.; Reffert, S.; Cifuentes, C.; Espinoza, N.; Perger, M.; Kossakowski, D.; Bluhm, P.; Guillén, C. Cardona; Kreidberg, L.; Cartwright, S.; Charbonneau, D.; Chaturvedi, P.; Guerra, P.; Hart, R.; Henze, C.; Jensen, E. L. N.; Kielkopf, J. F.; Kunimoto, M.; Morgan, E. H.; Pavlov, A.; Quintana, E. V.; Rodríguez López, C.; Schöfer, P.; Trifonov, T.; West, R.
Germany, Spain, United States, United Kingdom, Australia, Belgium
Abstract
We present the discovery of a transiting mini-Neptune around TOI-1201, a relatively bright and moderately young early M dwarf (J ≈ 9.5 mag, ~600-800 Myr) in an equal-mass ~8 arcsecond-wide binary system, using data from the Transiting Exoplanet Survey Satellite, along with follow-up transit observations. With an orbital period of 2.49 d, TOI-1201 b is a warm mini-Neptune with a radius of Rb = 2.415 ± 0.090 R⊕. This signal is also present in the precise radial velocity measurements from CARMENES, confirming the existence of the planet and providing a planetary mass of Mb = 6.28 ± 0.88 M⊕ and, thus, an estimated bulk density of 2.45−0.42+0.48 g cm−3. The spectroscopic observations additionally show evidence of a signal with a period of 19 d and a long periodic variation of undetermined origin. In combination with ground-based photometric monitoring from WASP-South and ASAS-SN, we attribute the 19 d signal to the stellar rotation period (Prot = 19-23 d), although we cannot rule out that the variation seen in photometry belongs to the visually close binary companion. We calculate precise stellar parameters for both TOI-1201 and its companion. The transiting planet is anexcellent target for atmosphere characterization (the transmission spectroscopy metric is 97−16+21) with the upcoming James Webb Space Telescope. It is also feasible to measure its spin-orbit alignment via the Rossiter-McLaughlin effect using current state-of-the-art spectrographs with submeter per second radial velocity precision.
Additional data (i.e., stellar activity indicators) are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/656/A124