TIC-320687387 B: a long-period eclipsing M-dwarf close to the hydrogen burning limit
Abstract
We are using precise radial velocities from CORALIE together with precision photometry from the Next Generation Transit Survey (NGTS) to follow-up stars with single-transit events detected with the Transiting Exoplanet Survey Satellite (TESS). As part of this survey, we identified a single transit on the star TIC-320687387, a bright (T = 11.6) G-dwarf observed by TESS in Sectors 13 and 27. From subsequent monitoring of TIC-320687387 with CORALIE, NGTS, and Lesedi we determined that the companion, TIC-320687387 B, is a very low-mass star with a mass of $96.2 \pm _{2.0}^{1.9}$ MJ and radius of $1.14 \pm _{0.02}^{0.02}$ RJ placing it close to the hydrogen burning limit (~80 MJ). TIC-320687387 B is tidally decoupled and has an eccentric orbit, with a period of 29.77381 d and an eccentricity of 0.366 ± 0.003. Eclipsing systems such as TIC-320687387 AB allow us to test stellar evolution models for low-mass stars, which in turn are needed to calculate accurate masses and radii for exoplanets orbiting single low-mass stars. The sizeable orbital period of TIC-320687387 B makes it particularly valuable as its evolution can be assumed to be free from perturbations caused by tidal interactions with its G-type host star.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- June 2022
- DOI:
- 10.1093/mnras/stac798
- arXiv:
- arXiv:2201.01713
- Bibcode:
- 2022MNRAS.513.1785G
- Keywords:
-
- binaries: eclipsing;
- Astrophysics - Solar and Stellar Astrophysics;
- Astrophysics - Earth and Planetary Astrophysics
- E-Print:
- 9 pages, 6 figures, 4 tables. Submitted to MNRAS