White dwarf-main sequence binaries identified from the LAMOST pilot survey

TL;DR

This paper reports the identification and analysis of 28 white dwarf-main sequence binaries from the LAMOST pilot survey, including new discoveries, parameter derivations, and potential post-common-envelope binary candidates.

Contribution

It introduces a new method to identify WDMS binaries from LAMOST data based on SDSS color criteria and provides detailed stellar parameters for a subset of these binaries.

Findings

28 WDMS binaries identified, including 19 new discoveries.

Derived stellar parameters and cooling ages for 10 binaries.

Two candidates for post-common-envelope binaries found.

Abstract

We present a set of white dwarf-main sequence (WDMS) binaries identified spectroscopically from the Large sky Area Multi-Object fiber Spectroscopic Telescope (LAMOST, also called the Guo Shou Jing Telescope) pilot survey. We develop a color selection criteria based on what is so far the largest and most complete Sloan Digital Sky Survey (SDSS) DR7 WDMS binary catalog and identify 28 WDMS binaries within the LAMOST pilot survey. The primaries in our binary sample are mostly DA white dwarfs except for one DB white dwarf. We derive the stellar atmospheric parameters, masses, and radii for the two components of 10 of our binaries. We also provide cooling ages for the white dwarf primaries as well as the spectral types for the companion stars of these 10 WDMS binaries. These binaries tend to contain hot white dwarfs and early-type companions. Through cross-identification, we note that nine binaries in our sample have been published in the SDSS DR7 WDMS binary catalog. Nineteen spectroscopic WDMS binaries identified by the LAMOST pilot survey are new. Using the 3$\sigma$ radial velocity variation as a criterion, we find two post-common-envelope binary candidates from our WDMS binary sample.