New SB1s with Spectroscopic Orbits from LAMOST-LRS

Abstract

The LAMOST Low-Resolution Spectroscopic (LAMOST-LRS) Survey provides radial velocities of 10 million stars. These observations can be used to identify new single-lined spectroscopic binaries (SB1s) with their preliminary spectroscopic orbits. First, we perform a statistical χ 2 test on a subsample of LAMOST-LRS stars with velocity observations sufficient for the present work to obtain a set of 6852 radial velocity variables. Subsequently, we discard 399 astrophysical variables through crossmatching with variable catalogs, resulting in 1297 SB1 candidates. Finally, in order to reliably identify SB1s among these SB1 candidates, we employ a combination of The joker, rvfit, and Levenberg–Marquardt algorithms to give the best-fit solutions. An SB1 is identified if its orbital solution satisfies the criteria of the goodness-of-fit statistic (F2) < 3.1, the signal significance > 10, and the maximum gap in phase (phase_gap_max) < 0.3. Our final catalog of SB1s contains 255 systems, 168 of which are newly discovered ones. Cross validation results indicate that the determined orbital periods are consistent with periods of external catalogs within 1σ uncertainties. The period–eccentricity diagram illustrates that a majority of short-period binaries have small eccentricities. Furthermore, in comparison to the general sample, the SB1 catalog exhibits a relatively higher ratio of dwarfs than giants and a slightly lower metallicity.