A super-Earth and a sub-Neptune orbiting the bright, quiet M3 dwarf TOI-1266
Watson, A. M.; Bouchy, F.; Queloz, D.; Heng, K.; Dai, F.; Vanderburg, A.; Winn, J. N.; Suárez, J. C.; Roy, A.; Benz, W.; Barrado, D.; Collins, K. A.; Demory, B. -O.; Gillon, M.; Jenkins, J. M.; Seager, S.; Twicken, J. D.; Lillo-Box, J.; Morales-Calderón, M.; Jehin, E.; Sabin, L.; Barkaoui, K.; Benkhaldoun, Z.; Bieryla, A.; Latham, D. W.; Ricker, G.; Petrucci, R.; Jofré, E.; Huang, C. X.; McCormac, J.; Isaacson, H.; Chontos, A.; Giacalone, S.; Huber, D.; Kane, S. R.; Robertson, P.; Srdoc, G.; Stassun, K. G.; Herrera, J.; Morris, B. M.; Mordasini, C.; Guerra, P.; de Wit, J.; Triaud, A. H. M. J.; Essack, Z.; Dressing, C. D.; Burdanov, A.; Garcia, L. J.; Gómez Maqueo Chew, Y.; Niraula, P.; Pozuelos, F. J.; Rackham, B. V.; Schroffenegger, U.; Grimm, S. L.; Sestovic, M.; Haldemann, J.; Maigné, V.; Savel, A. B.; Soubkiou, A.; Zambelli, R.; Calvario-Velásquez, T.; Franco Herrera, J. A.; Colorado, E.; Cadena Zepeda, E. O.; Figueroa, L.; Lugo-Ibarra, E. E.; Carigi, L.; Guisa, G.; Sierra Díaz, G.; Batalha, N. M.; Ghachoui, M.; Lissauer, J. J.; Weiss, L. M.
Switzerland, Belgium, Mexico, Argentina, United Kingdom, Morocco, United States, Spain, Croatia, Italy, Australia
Abstract
We report the discovery and characterisation of a super-Earth and a sub-Neptune transiting the bright (K = 8.8), quiet, and nearby (37 pc) M3V dwarf TOI-1266. We validate the planetary nature of TOI-1266 b and c using four sectors of TESS photometry and data from the newly-commissioned 1-m SAINT-EX telescope located in San Pedro Mártir (México). We also include additional ground-based follow-up photometry as well as high-resolution spectroscopy and high-angular imaging observations. The inner, larger planet has a radius of R = 2.37-0.12+0.16 R⊕ and an orbital period of 10.9 days. The outer, smaller planet has a radius of R = 1.56-0.13+0.15 R⊕ on an 18.8-day orbit. The data are found to be consistent with circular, co-planar and stable orbits that are weakly influenced by the 2:1 mean motion resonance. Our TTV analysis of the combined dataset enables model-independent constraints on the masses and eccentricities of the planets. We find planetary masses of Mp = 13.5-9.0+11.0 M⊕ (<36.8 M⊕ at 2-σ) for TOI-1266 b and 2.2-1.5+2.0 M⊕ (<5.7 M⊕ at 2-σ) for TOI-1266 c. We find small but non-zero orbital eccentricities of 0.09-0.05+0.06 (<0.21 at 2-σ) for TOI-1266 b and 0.04 ± 0.03 (< 0.10 at 2-σ) for TOI-1266 c. The equilibrium temperatures of both planets are of 413 ± 20 and 344 ± 16 K, respectively, assuming a null Bond albedo and uniform heat redistribution from the day-side to the night-side hemisphere. The host brightness and negligible activity combined with the planetary system architecture and favourable planet-to-star radii ratios makes TOI-1266 an exquisite system for a detailed characterisation.