APOGEE: Properties & radial velocities of binaries

This holds even when multiple stars are captured in the same spectrum, as happens most commonly with double-lined spectroscopic binaries (SB2s), although random line-of-sight alignments of unrelated stars can also occur. We develop a code that autonomously identifies SB2s and higher order multiples in the APOGEE spectra, resulting in 7273 candidate SB2s, 813 SB3s, and 19 SB4s.

We estimate the mass ratios of binaries, and for a subset of these systems with a sufficient number of measurements we perform a complete orbital fit, confirming that most systems with periods of <10days have circularized. Overall, we find an SB2 fraction (FSB2) ~3% among main-sequence dwarfs, and that there is not a significant trend in FSB2 with temperature of a star. We are also able to recover a higher FSB2 in sources with lower metallicity, however there are some observational biases.