A super-Earth and a sub-Neptune orbiting the bright, quiet M3 dwarf TOI-1266
Creators: name: Demory, B. -O.
name: Pozuelos, F. J.
name: Chew, Y. Gomez Maqueo
name: Sabin, L.
name: Petrucci, R.
name: Schroffenegger, U.
name: Grimm, S. L.
name: Sestovic, M.
name: Gillon, M.
name: McCormac, J.
name: Barkaoui, K.
name: Benz, W.
name: Bieryla, A.
name: Bouchy, F.
name: Burdanov, A.
name: Collins, K. A.
name: de Wit, J.
name: Dressing, C. D.
name: Garcia, L. J.
name: Giacalone, S.
name: Guerra, P.
name: Haldemann, J.
name: Heng, K.
name: Jehin, E.
name: Jofre, E.
name: Kane, S. R.
name: Lillo-Box, J.
name: Maigne, V.
name: Mordasini, C.
name: Morris, B. M.
name: Niraula, P.
name: Queloz, D.
name: Rackham, B. V.
name: Savel, A. B.
name: Soubkiou, A.
name: Srdoc, G.
name: Stassun, K. G.
name: Triaud, A. H. M. J.
name: Zambelli, R.
name: Ricker, G.
name: Latham, D. W.
name: Seager, S.
name: Winn, J. N.
name: Jenkins, J. M.
name: Calvario-Velasquez, T.
name: Herrera, J. A. Franco
name: Colorado, E.
name: Zepeda, E. O. Cadena
name: Figueroa, L.
name: Watson, A. M.
name: Lugo-Ibarra, E. E.
name: Carigi, L.
name: Guisa, G.
name: Herrera, J.
name: Diaz, G. Sierra
name: Suarez, J. C.
name: Barrado, D.
name: Batalha, N. M.
name: Benkhaldoun, Z.
name: Chontos, A.
name: Dai, F.
name: Essack, Z.
name: Ghachoui, M.
name: Huang, C. X.
name: Huber, D.
name: Isaacson, H.
name: Lissauer, J. J.
name: Morales-Calderon, M.
name: Robertson, P.
name: Roy, A.
name: Twicken, J. D.
name: Vanderburg, A.
name: Weiss, L. M.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: 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 (Mexico). 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$_{\oplus}$ and an orbital period of 10.9 days. The outer, smaller planet has a radius of $R=1.56_{-0.13}^{+0.15}$ R$_{\oplus}$ 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 $M_\mathrm{p}$ = $13.5_{-9.0}^{+11.0}$ $\mathrm{M_{\oplus}}$ ($&lt;36.8$ $\mathrm{M_{\oplus}}$ at 2-$σ$) for TOI-1266 b and $2.2_{-1.5}^{+2.0}$ $\mathrm{M_{\oplus}}$ ($&lt;5.7$ $\mathrm{M_{\oplus}}$ at 2-$σ$) for TOI-1266 c. We find small but non-zero orbital eccentricities of $0.09_{-0.05}^{+0.06}$ ($&lt;0.21$ at 2-$σ$) for TOI-1266 b and $0.04\pm0.03$ ($&lt;0.10$ at 2-$σ$) for TOI-1266 c. The equilibrium temperatures of both planets are of $413\pm20$ K and $344\pm16$ 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.
description: In press. Accepted for publication in Astronomy and Astrophysics on 20 July 2020