Volume 604, August 2017
|Number of page(s)||6|
|Published online||01 August 2017|
The EBLM project
III. A Saturn-size low-mass star at the hydrogen-burning limit⋆
1 Cavendish Laboratory, J J Thomson Avenue, Cambridge, CB3 0HE, UK
2 Institute of Astronomy, Madingley Road, Cambridge, CB3 0HA, UK
3 Observatoire Astronomique de l’Université de Genève, Chemin des Maillettes 51, 1290 Sauverny, Switzerland
4 Astrophysics Group, Keele University, Staffordshire, ST55 BG, UK
5 Space Research Institute, Austrian Academy of Sciences, Schmiedlstr. 6, 8042 Graz, Austria
6 Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany
7 SUPA, School of Physics & Astronomy, University of St Andrews, North Haugh, KY16 9SS, St Andrews, Fife, UK
8 Department of Physics, University of Warwick, Coventry, CV4 7AL, UK
9 Université de Liège, Allée du 6 août 17, Sart Tilman, 4000 Liège 1, Belgium
10 Instituto de Astronomía, Universidad Nacional Autónoma de México, Ciudad Universitaria, 04510 Ciudad de México, México
11 Hobart and William Smith Colleges, Department of Physics, Geneva, NY 14456, USA
Received: 4 May 2017
Accepted: 12 June 2017
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.
Key words: binaries: eclipsing / binaries: spectroscopic / stars: low-mass / techniques: spectroscopic / techniques: photometric / stars: individual: EBLM J0555-57Ab
The photometry tables and radial velocities are only available at the CDS and on demand via anonymous ftp to cdsarc.u-strasbg.fr (18.104.22.168) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/604/L6
© ESO, 2017
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