Assessing Spectroscopic Binary Multiplicity Properties Using Robo-AO Imaging

• Published in: The Astrophysical journal 2020-10, Vol.902 (2), p.107
• Main Authors: Laos, Stefan, Stassun, Keivan G., Mathieu, Robert D.
• Format: Article
• Language: English
• Subjects: Adaptive optics; Adaptive systems; Angular momentum; Astrophysics; Binary stars; Companion stars; Dynamical evolution; Eclipsing binary stars; Momentum transfer; Optics; Orbits; Point spread functions; Pre-main sequence stars; Star formation; Trinary stars
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/1538-4357/abb3fe

We present higher-order multiplicity results for 60 solar-type spectroscopic binaries based on 0.75 μ m imaging data taken by the robotic adaptive optics (Robo-AO) system at the Kitt Peak 2.1 m telescope. Our contrast curves show sensitivity up to ∼5 mag at ∼1″ separation; at very small separations, we identify candidate companions from image deviations relative to the point spread function. We find candidate tertiary companions for 62% of our binaries overall, but we find that this fraction is a strong function of the inner binary orbital period; it ranges from ∼47% for P bin  > 30 days to as high as ∼90% for P bin ≲ 5 days. We similarly find an increasing tertiary companion frequency for shorter-period binaries in a secondary sample of Kepler eclipsing binaries observed by Robo-AO. Using Gaia distances, we estimate an upper limit orbital period for each tertiary candidate and compare the tertiary-to-binary period ratios for systems in the field versus those in star-forming regions. Taken all together, these results provide further evidence for angular momentum transfer from three-body interactions, resulting in tight binaries with tertiaries that widen from pre-main-sequence to field ages.