TOI-6508b: A massive transiting brown dwarf orbiting a low-mass star

TL;DR

This paper reports the discovery and characterization of TOI-6508b, a massive transiting brown dwarf orbiting a low-mass star, using TESS data and ground-based follow-up, highlighting its unique properties and significance.

Contribution

It presents the discovery and detailed analysis of TOI-6508b, one of the few known transiting brown dwarfs around a low-mass star, with precise measurements and orbital modeling.

Findings

TOI-6508b has a mass of approximately 72.5 MJup.

It orbits its host star with a period of 19 days and eccentricity of 0.28.

The host star is a very low-mass star with 0.174 M_Sun.

Abstract

We report the discovery of a transiting brown dwarf orbiting a low-mass star, TOI-6508b. Today, only ~50 transiting brown dwarfs have been discovered. TOI-6508b was first detected with data from the Transiting Exoplanet Survey Satellite (TESS) in Sectors 10, 37, and 63. Ground-based follow-up photometric data were collected with the SPECULOOS-South and LCOGT-1.0m telescopes, and RV measurements were obtained with the Near InfraRed Planet Searcher (NIRPS) spectrograph. We find that TOI-6508b has a mass of Mp=72.5+7.6-5.1MJup and a radius of Rp=1.03+/-0.03RJup. Our modeling shows that the data are consistent with an eccentric orbit of 19day and an eccentricity of e=0.28+0.09-0.08. TOI-6508b has a mass ratio of M_BD/Ms=0.40, makes it the second highest mass ratio brown dwarf that transits a low-mass star. The host has a mass of Ms=0.174+/-0.004M_Sun, a radius of Rs=0.205+/-0.006R_Sun, an effective temperature of Teff=2930+/-70K, and a metallicity of [Fe/H]=-0.22+/-0.08. This makes TOI-6508b an interesting discovery that has come to light in a region still sparsely populated.