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.
@article{arxiv.2502.19940,
title = {TOI-6508b: A massive transiting brown dwarf orbiting a low-mass star},
author = {K. Barkaoui and D. Sebastian and S. Zúñiga-Fernández and A. H. M. J. Triaud and B. V. Rackham and A. J. Burgasser and T. W. Carmichael and M. Gillon and C. Theissen and E. Softich and B. Rojas-Ayala and G. Srdoc and A. Soubkiou and A. Fukui and M. Timmermans and M. Stalport and A. Burdanov and D. R. Ciardi and K. A. Collins and Y. T. Davis and F. Davoudi and J. de Wit and B. O. Demory and S. Deveny and G. Dransfield and E. Ducrot and L. Florian and T. Gan and Y. Gómez Maqueo Chew and M. J. Hooton and S. B. Howell and J. M. Jenkins and C. Littlefield and E. L. Martín and F. Murgas and P. Niraula and E. Palle and P. P. Pedersen and F. J. Pozuelos and D. Queloz and G. Ricker and R. P. Schwarz and S. Seager and A. Shporer and M. G. Scott and C. Stockdale and J. Winn},
journal= {arXiv preprint arXiv:2502.19940},
year = {2025}
}
Comments
17 pages, Accepted for publication in Astronomy and Astrophysics