The Spectroscopic Binaries from LAMOST Medium-Resolution Survey (MRS). I. Searching for Double-lined Spectroscopic Binaries (SB2s) with Convolutional Neural Network

Abstract

We developed a convolutional neural network (CNN) model to distinguish the double-lined spectroscopic binaries (SB2s) from others based on single exposure medium-resolution spectra ($R\sim 7,500$). The training set consists of a large set of mock spectra of single stars and binaries synthesized based on the MIST stellar evolutionary model and ATLAS9 atmospheric model. Our model reaches a novel theoretic false positive rate by adding a proper penalty on the negative sample (e.g., 0.12\% and 0.16\% for the blue/red arm when the penalty parameter $\Lambda =16$). Tests show that the performance is as expected and favors FGK-type Main-sequence binaries with high mass ratio ($q\ge 0.7$) and large radial velocity separation ($\Delta v\ge 50\mathrm{km}{\mathrm{s}}^{-1}$). Although the real false positive rate can not be estimated reliably, validating on eclipsing binaries identified from Kepler light curves indicates that our model predicts low binary probabilities at eclipsing phases (0, 0.5, and 1.0) as expected. The color-magnitude diagram also helps illustrate its feasibility and capability of identifying FGK MS binaries from spectra. We conclude that this model is reasonably reliable and can provide an automatic approach to identify SB2s with period $\lesssim 10$ days. This work yields a catalog of binary probabilities for over 5 million spectra of 1 million sources from the LAMOST medium-resolution survey (MRS), and a catalog of 2198 SB2 candidates whose physical properties will be analyzed in our following-up paper. Data products are made publicly available at the journal as well as our Github website.

19 pages, 13 figures, accepted for publication in ApJS

References in corpus (19)

• The Gaia mission
• The Transiting Exoplanet Survey Satellite
• The K2 Mission: Characterization and Early results
• The Radial Velocity Experiment (RAVE): first data release
• The GALAH Survey: Scientific Motivation
• A wide star-black-hole binary system from radial-velocity measurements
• The Joker: A custom Monte Carlo sampler for binary-star and exoplanet radial velocity data
• Self-consistent Stellar Radial Velocities from LAMOST Medium-Resolution Survey (MRS) DR7
• Signatures of unresolved binaries in stellar spectra: implications for spectral fitting
• The Galah Survey: Classification and diagnostics with t-SNE reduction of spectral information
• The Gaia-ESO Survey: double, triple and quadruple-line spectroscopic binary candidates
• The binarity of Milky Way F,G,K stars as a function of effective temperature and metallicity
• Double-lined Spectroscopic Binary Stars in the Radial Velocity Experiment Survey
• The Close Binary Fraction as a Function of Stellar Parameters in APOGEE: A Strong Anti-Correlation With $\alpha$ Abundances
• Stellar loci II. a model-free estimate of the binary fraction for field FGK stars
• Double-, triple-line spectroscopic candidates in the LAMOST Medium-Resolution Spectroscopic Survey
• Minute-cadence Observations of the LAMOST Fields with the TMTS: I. Methodology of Detecting Short-period Variables and Results from the first-year Survey
• A Catalog of Short Period Spectroscopic and Eclipsing Binaries Identified from the LAMOST & PTF Surveys
• Asteroseismology of RRab variable star EZ Cnc from K2 photometry and LAMOST spectroscopy

Cited by in corpus (1)

• Detection of 2460 SB2 candidates in the LAMOST-MRS, using projected rotational velocities and a binary spectral model