TOI-908: a planet at the edge of the Neptune desert transiting a G-type star
astro-ph.EP
/ Authors
Faith Hawthorn, Daniel Bayliss, David J. Armstrong, Jorge Fernández Fernández, Ares Osborn, Sérgio G. Sousa, Vardan Adibekyan, Jeanne Davoult, Karen A. Collins, Yann Alibert
and 29 more authors
Susana C. C. Barros, François Bouchy, Matteo Brogi, David R. Ciardi, Tansu Daylan, Elisa Delgado Mena, Olivier D. S. Demangeon, Rodrigo F. Díaz, Tianjun Gan, Keith Horne, Sergio Hoyer, Alan M. Levine, Jorge Lillo-Box, Louise D. Nielsen, Hugh P. Osborn, George R. Ricker, José Rodrigues, Nuno C. Santos, Richard P. Schwarz, Sara Seager, Juan Serrano Bell, Avi Shporer
/ 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 ($T_{eff}$ = 5626 $\pm$ 61 K) solar-like star with a mass of 0.950 $\pm$ 0.010 $M_{\odot}$ and a radius of 1.028 $\pm$ 0.030 $R_{\odot}$. The planet, TOI-908 b, is a 3.18 $\pm$ 0.16 $R_{\oplus}$ planet in a 3.18 day orbit. Radial velocity measurements from HARPS reveal TOI-908 b has a mass of approximately 16.1 $\pm$ 4.1 $M_{\oplus}$ , 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.