The EBLM project : III. A Saturn-size low-mass star at the hydrogen-burning limit

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 ± 4 MJup (0.081 M⊙) and a radius of 0.84+ 0.14 -0.04RJup (0.084 R⊙) that is comparable to that of Saturn. EBLM J0555-57Ab has a surface gravity log g2 =5.50+ 0.03 -0.13 and is one of the densest non-stellar-remnant objects currently known. These measurements are consistent with models of low-mass stars.

Citation

Von Boetticher , A , Triaud , A H M J , Queloz , DI , Gill , S , Lendl , M , Delrez , L , Anderson , D R , Cameron , A C , Faedi , F , Gillon , M , Chew , Y G M , Hebb , L , Hellier , C , Jehin , E , Maxted , P F L , Martin , D V , Pepe , F , Pollacco , D , Ségransan , D , Smalley , B , Udry , S & West , R 2017 , ' The EBLM project : III. A Saturn-size low-mass star at the hydrogen-burning limit ' , Astronomy & Astrophysics , vol. 604 , L6 . https://doi.org/10.1051/0004-6361/201731107

Publication

Astronomy & Astrophysics

Status

Peer reviewed

DOI

https://doi.org/10.1051/0004-6361/201731107

ISSN

0004-6361

Type

Journal article

Rights

© ESO, 2017. This work has been made available online in accordance with the publisher’s policies. This is the author created accepted version manuscript following peer review and as such may differ slightly from the final published version. The final published version of this work is available at https://doi.org/10.1051/0004-6361/201731107

Description

This work was partially supported by a grant from the Simons Foundation (PI Queloz, grant number 327127).

St Andrews Research Repository