Two intermediate-mass brown dwarfs from the TESS mission

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 ± 0.00016 days, a mass of Mb = 63.8 ± 1.0 MJ, and a radius of Rb = 0.75 ± 0.02 RJ. Its host star, TOI-569, has a mass of M? = 1.21± 0.03 M , a radius of R? = 1.48± 0.03 R , and an effective temperature of Teff = 5705 ± 76K. TOI-1406b has an orbital period of P = 10.57415 ± 0.00063 days, a mass of Mb = 46.0 ± 2.7 MJ, and a radius of Rb = 0.86 ± 0.03 RJ. The host star for this BD has a mass of M? = 1.18± 0.09 M , a radius of R? = 1.35± 0.03 R , and an effective temperature of Teff = 6290 ± 100K. Both BDs are in circular orbits around their host stars and join an increasing number of known transiting intermediate-mass BDs. 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 MJ and one of two to have a circular orbit at a period near 10 days (with the first being KOI-205b). Based on the relatively long circularization timescales for both BDs, we believe that they must have formed in nearly circular orbits and migrated inward to their present orbital configurations.