Abstract
Abstract Radial velocity (RV) variable stars are important in astrophysics. The Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) spectroscopic survey has provided ∼6.5 million stellar spectra in its Data Release 4 (DR4). During the survey ∼4.7 million unique sources were targeted and ∼1 million stars observed repeatedly. The probabilities of stars being RV variables are estimated by comparing the observed RV variations with simulated ones. We build a catalog of 80,702 RV variable candidates with probability greater than 0.60 by analyzing the multi-epoch sources covered by LAMOST DR4. Simulations and cross-identifications show that the purity of the catalog is higher than 80%. The catalog consists of 77% binary systems and 7% pulsating stars as well as 16% pollution by single stars. 3138 RV variables are classified through cross-identifications with published results in literatures. By using the 3138 sources common in both LAMOST and a collection of published RV variable catalogs, we are able to analyze LAMOST’s RV variable detection rate. The efficiency of the method adopted in this work relies not only on the sampling frequency of observations but also periods and amplitudes of RV variables. With the progress of LAMOST, Gaia, and other surveys, more and more RV variables will be confirmed and classified. This catalog is valuable for other large-scale surveys, especially for RV variable searches. The catalog will be released according to the LAMOST Data Policy via http://dr4.lamost.org.
Highlights
Binary stars play a crucial role in astrophysics
Statistics and identifications of binary systems are significant for several reasons, the major ones being that such basic issues as star formation and evolution, the initial mass function (IMF) and Galactic chemical evolution are all influenced by the binary properties of the stellar population
For the binary systems MB, we assume that: (1) the RVs are contributed by their primary stars; (2) their orbital orientations are isotropic in 3D space and initial phases follow a uniform distribution; (3) their primary masses follow the measured mass distribution of the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) sample, which are determined by fitting the atmospheric parameters with the Yonsei-Yale (YY) isochrones (Demarque et al 2004, and references therein); (4) the mass ratio q follows a power-law distribution (f (q) ∝ q0.3±0.1, e.g. Duchene & Kraus 2013); (5) for the orbital period distribution, a log-normal profile is adopted
Summary
Binary stars play a crucial role in astrophysics. Statistics and identifications of binary systems are significant for several reasons, the major ones being that such basic issues as star formation and evolution, the initial mass function (IMF) and Galactic chemical evolution are all influenced by the binary properties of the stellar population. Large Sky Area MultiObject Fiber Spectroscopic Telescope (LAMOST) provided millions of stellar spectra, of which about 20% of the targets have been observed repeatedly The quantity of these spectra can enhance time-domain studies of stars, stellar parameters, and their RVs and help select and confirm variable candidates. The LAMOST spectroscopic survey provides the largest database of low-resolution (R∼2000) spectra to measure stellar atmospheric parameters and radial velocities for millions of stars (Cui et al 2012; Zhao et al 2012; Deng et al 2012; Liu et al 2014; Yuan et al 2015b). To identify binary systems or candidates reliably, we limit the SNR of spectra greater than 10
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