Binaries with possible compact components discovered from the LAMOST Time-Domain Survey of four $K$2 plates

TL;DR

This study utilizes LAMOST time-domain spectroscopic data to identify binary systems with potential compact objects like white dwarfs or neutron stars, revealing three such systems through radial velocity monitoring.

Contribution

First application of LAMOST time-domain data to discover binaries with compact components, estimating their parameters and confirming the presence of unseen compact objects.

Findings

Identified three binary systems with potential compact objects.

No double-lined spectral features detected in the systems.

No X-ray counterparts found, but UV companions detected for two systems.

Abstract

Time-domain (TD) spectroscopic data from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) can provide accurate and high-cadence radial velocities (RVs). In this work, we search for binaries with compact components with RV monitoring method by using the LAMOST TD survey of four $K$2 plates. Three binary systems including an unseen white dwarf or neutron star are found. For each binary system, we estimate the stellar parameters of the visible star and orbital parameters, and finally calculate the binary mass function and the minimum mass of the unseen star. No obvious double-lined feature is seen from the LAMOST medium-resolution spectra of the three sources. In addition, we found no X-ray counterpart for all these sources but UV companions for two of them. Spectral disentangling also shows no additional component with optical absorption spectra, supporting that these systems contain compact objects.