<i>TESS</i> discovery of a sub-Neptune orbiting a mid-M dwarf TOI-2136
Tianjun Gan, Abderahmane Soubkiou, Sharon X. Wang, Z. Benkhaldoun, Shude Mao, Étienne Artigau, P. Fouqué, L. Arnold, Steven Giacalone, Christopher A Theissen, Christian Aganze, Adam J. Burgasser, Karen A. Collins, Avi Shporer, Khalid Barkaoui, Mourad Ghachoui, Steve B. Howell, C. Lamman, O. D. S. Demangeon, Artem Burdanov, Charles Cadieux, J. Chouqar, Kevin I. Collins, Neil J. Cook, L. Delrez, Brice-Olivier Demory, René Doyon, Georgina Dransfield, Courtney D. Dressing, Elsa Ducrot, Jiahao Fan, L. J. Garcia, Holden Gill, M. Gillon, Crystal L. Gnilka, Yilen Gómez Maqueo Chew, Maximilian N. Günther, Christopher E. Henze, Chelsea X. Huang, Emmanuël Jehin, Eric L. N. Jensen, Zitao Lin, N. Manset, J. McCormac, C. A. Murray, Prajwal Niraula, P.P. Pedersen, F. J. Pozuelos, D. Queloz, Benjamin V. Rackham, Arjun B Savel, N. Schanche, Richard P. Schwarz, Daniel Sebastian, Samantha Thompson, Mathilde Timmermans, A. H. M. J. Triaud, M. Vezie, Robert D. Wells, Julien de Wit, G. Ricker, R. Vanderspek, David W. Latham, Sara Seager, Joshua N. Winn, Jon M. Jenkins
Abstract
ABSTRACT We present the discovery of TOI-2136 b, a sub-Neptune planet transiting a nearby M4.5V-type star every 7.85 d, identified through photometric measurements from the Transiting Exoplanet Survey Satellite (TESS) mission. The host star is located 33 pc away with a radius of R* = 0.34 ± 0.02 R⊙, a mass of $0.34\pm 0.02 \, \mathrm{M}_{\odot }$, and an effective temperature of 3342 ± 100 K. We estimate its stellar rotation period to be 75 ± 5 d based on archival long-term photometry. We confirm and characterize the planet based on a series of ground-based multiwavelength photometry, high-angular-resolution imaging observations, and precise radial velocities from Canada–France–Hawaii Telescope (CFHT)/SpectroPolarimètre InfraROUge (SPIRou). Our joint analysis reveals that the planet has a radius of 2.20 ± 0.17 R⊕ and a mass of 6.4 ± 2.4 M⊕. The mass and radius of TOI-2136 b are consistent with a broad range of compositions, from water-ice to gas-dominated worlds. TOI-2136 b falls close to the radius valley for M dwarfs predicted by thermally driven atmospheric mass-loss models, making it an interesting target for future studies of its interior structure and atmospheric properties.