15 000 ellipsoidal binary candidates in TESS: Orbital periods, binary fraction, and tertiary companions
Abstract
We present a homogeneously selected sample of 15 779 candidate binary systems with main sequence primary stars and orbital periods shorter than 5 d. The targets were selected from TESS full-frame image light curves on the basis of their tidally induced ellipsoidal modulation. Spectroscopic follow-up suggests a sample purity of 83 ± 13 per cent. Injection-recovery tests allow us to estimate our overall completeness as 28 ± 3 per cent with Porb < 3 d and to quantify our selection effects. 39 ± 4 per cent of our sample are contact binary systems, and we disentangle the period distributions of the contact and detached binaries. We derive the orbital period distribution of the main-sequence binary population at short orbital periods, finding a distribution continuous with the lognormal distribution previously found for solar-type stars at longer periods, but with a significant steepening at Porb ≲ 3 d, and a pile-up of contact binaries at Porb ≈ 0.4 d. Companions in the period range of 1-5 d are an order of magnitude more frequent around stars hotter than $\approx 6250\, \rm K$ (the Kraft break) when compared to cooler stars, suggesting that magnetic braking shortens the lifetime of cooler binary systems. However, the period distribution in the range 1-10 d is independent of temperature. We detect resolved tertiary companions to 9.0 ± 0.2 per cent of our binaries with a median separation of 3200 au. The frequency of tertiary companions rises to 29 ± 5 per cent among the systems with the shortest ellipsoidal periods. This large binary sample with quantified selection effects will be a powerful resource for future studies of detached and contact binary systems with Porb<5 d.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- June 2023
- DOI:
- 10.1093/mnras/stad915
- arXiv:
- arXiv:2211.06194
- Bibcode:
- 2023MNRAS.522...29G
- Keywords:
-
- binaries: close;
- binaries: general;
- catalogues;
- stars: statistics;
- binaries: eclipsing;
- binaries: spectroscopic;
- Astrophysics - Solar and Stellar Astrophysics;
- Astrophysics - Earth and Planetary Astrophysics
- E-Print:
- 30 pages, 24 figures, accepted to MNRAS (updated to peer-reviewed version)