TOI-908: a planet at the edge of the Neptune desert transiting a G-type star
Latham, David W.; Fernández Fernández, Jorge; Wheatley, Peter J.; Brogi, Matteo; Bayliss, Daniel; Horne, Keith; Ziegler, Carl; Collins, Karen A.; Ricker, George R.; Seager, Sara; Winn, Joshua N.; Jenkins, Jon M.; Shporer, Avi; Ciardi, David R.; Armstrong, David J.; Osborn, Ares; Udry, Stéphane; Stockdale, Chris; Jensen, Eric L. N.; Kielkopf, John F.; Levine, Alan M.; Daylan, Tansu; Gan, Tianjun; Bouchy, François; Nielsen, Louise D.; Osborn, Hugh P.; Schwarz, Richard P.; Sousa, Sérgio G.; Tenenbaum, Peter; Lillo-Box, Jorge; Díaz, Rodrigo F.; Adibekyan, Vardan; Hoyer, Sergio; Hawthorn, Faith; Rodrigues, José; Santos, Nuno C.; Strøm, Paul A.; Demangeon, Olivier D. S.; Serrano Bell, Juan; Kostov, Veselin; Barros, Susana C. C.; Davoult, Jeanne; Alibert, Yann; Delgado Mena, Elisa
United Kingdom, Portugal, Switzerland, United States, Italy, Argentina, China, France, Spain, Germany, Australia
Abstract
We present the discovery of an exoplanet transiting TOI-908 (TIC-350153977) using data from TESS sectors 1, 12, 13, 27, 28, and 39. TOI-908 is a T = 10.7 mag G-dwarf (Teff = 5626 ± 61 K) solar-like star with a mass of 0.950 ± 0.010 M⊙ and a radius of 1.028 ± 0.030 R⊙. The planet, TOI-908 b, is a 3.18 ± 0.16 R⊕ planet in a 3.18 d orbit. Radial velocity measurements from HARPS reveal TOI-908 b has a mass of approximately 16.1 ± 4.1 M⊕, resulting in a bulk planetary density of $2.7^{+0.2}_{-0.4}$ g cm-3. TOI-908 b lies in a sparsely populated region of parameter space known as the Neptune desert. The planet likely began its life as a sub-Saturn planet before it experienced significant photoevaporation due to X-rays and extreme ultraviolet radiation from its host star, and is likely to continue evaporating, losing a significant fraction of its residual envelope mass.