paper

Two intermediate-mass transiting brown dwarfs from the TESS mission

arXiv:2002.01943 · doi:10.3847/1538-3881/ab9b84

Abstract

We report the discovery of two intermediate-mass brown dwarfs (BDs), TOI-569b and TOI-1406b, from NASA's Transiting Exoplanet Survey Satellite mission. TOI-569b has an orbital period of $P = 6.55604 \pm 0.00016$ days, a mass of $M_{b} = 64.1 \pm 1.9 M_{J}$ , and a radius of $R_{b} = 0.75 \pm 0.02 R_{J}$ . Its host star, TOI-569, has a mass of $M_{⋆} = 1.21 \pm 0.03 M_{⊙}$ , a radius of $R_{⋆} = 1.47 \pm 0.03 R_{⊙}$ , $[Fe/H] = + 0.29 \pm 0.09$ dex, and an effective temperature of $T_{eff} = 5768 \pm 110 K$ . TOI-1406b has an orbital period of $P = 10.57415 \pm 0.00063$ days, a mass of $M_{b} = 46.0 \pm 2.7 M_{J}$ , and a radius of $R_{b} = 0.86 \pm 0.03 R_{J}$ . The host star for this BD has a mass of $M_{⋆} = 1.18 \pm 0.09 M_{⊙}$ , a radius of $R_{⋆} = 1.35 \pm 0.03 R_{⊙}$ , $[Fe/H] = - 0.08 \pm 0.09$ dex and an effective temperature of $T_{eff} = 6290 \pm 100 K$ . Both BDs are in circular orbits around their host stars and are older than 3 Gyr based on stellar isochrone models of the stars. TOI-569 is one of two slightly evolved stars known to host a transiting BD (the other being KOI-415). TOI-1406b is one of three known transiting BDs to occupy the mass range of $40 - 50 M_{J}$ and one of two to have a circular orbit at a period near 10 days (with the first being KOI-205b).Both BDs have reliable ages from stellar isochrones in addition to their well-constrained masses and radii, making them particularly valuable as tests for substellar isochrones in the BD mass-radius diagram.

18 pages, 10 figures, 8 tables, accepted for publication in AJ