15 000 ellipsoidal binary candidates in TESS: Orbital periods, binary fraction, and tertiary companions

Matthew J. Green*, Dan Maoz, Tsevi Mazeh, Simchon Faigler, Sahar Shahaf, Roy Gomel, Kareem El-Badry, Hans Walter Rix

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

26 Scopus citations

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 ≈ 6250 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.

Original languageEnglish
Pages (from-to)29-55
Number of pages27
JournalMonthly Notices of the Royal Astronomical Society
Volume522
Issue number1
DOIs
StatePublished - 1 Jun 2023

Funding

FundersFunder number
National Aeronautics and Space Administration
Kavli Institute for Theoretical Physics, University of California, Santa Barbara
German Israeli Foundation for Science and Development
European Union’s FP7 Programme
German-Israeli Foundation for Scientific Research and Development
European Research Council
SAPHIRES
ELLC
Not added833031
Spondyloarthritis Research and Treatment Network2020
Science Mission Directorate2019
National Science FoundationPHY-1748958

    Keywords

    • binaries: close
    • binaries: eclipsing
    • binaries: general
    • binaries: spectroscopic
    • catalogues
    • stars: statistics

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