We report the discovery of an eclipsing binary system with mass-ratio q ∼ 0.07. After identifying a periodic photometric signal received by WASP, we obtained CORALIE spectroscopic radial velocities and follow-up light curves with the Euler and TRAPPIST telescopes. From a joint fit of these data we determine that EBLM J0555-57 consists of a sun-like primary star that is eclipsed by a low-mass companion, on a weakly eccentric 7.8-day orbit. Using a mass estimate for the primary star derived from stellar models, we determine a companion mass of 85±4MJup (0.081M⊙) and a radius of 0.84−0.04+0.14RJup (0.084R⊙) that is comparable to that of Saturn. EBLM J0555-57Ab has a surface gravity logg2=5.50−0.13+0.03 and is one of the densest non-stellar-remnant objects currently known. These measurements are consistent with models of low-mass stars.
@article{arxiv.1706.08781,
title = {The EBLM project III. A Saturn-size low-mass star at the hydrogen-burning limit},
author = {Alexander von Boetticher and Amaury H. M. J. Triaud and Didier Queloz and Sam Gill and Monika Lendl and Laetitia Delrez and David R. Anderson and Andrew Collier Cameron and Francesca Faedi and Michaël Gillon and Yilen Gómez Maqueo Chew and Leslie Hebb and Coel Hellier and Emmanuël Jehin and Pierre F. L. Maxted and David V. Martin and Francesco Pepe and Don Pollacco and Damien Ségransan and Barry Smalley and Stéphane Udry and Richard West},
journal= {arXiv preprint arXiv:1706.08781},
year = {2017}
}
Comments
Accepted for publication in A&A, 6 pages, 5 figures