Spectroscopically Identified Cataclysmic Variables from LAMOST survey. I. The Sample

TL;DR

This paper presents a spectroscopic catalog of 245 cataclysmic variables identified from LAMOST data, including new discoveries, classifications, and spectral analyses, enhancing understanding of CV properties and distributions.

Contribution

It introduces a large, spectroscopically confirmed CV sample from LAMOST, applying machine learning for candidate selection, and provides detailed spectral and distribution analyses.

Findings

Identification of 245 CVs, including 58 new candidates.

Classification into dwarf novae, nova-like, and magnetic CVs.

Spectral characteristics of high-inclination systems and systems with companions.

Abstract

A sample of Cataclysmic Variables (CVs) is presented including spectroscopically identified 380 spectra of 245 objects, of which 58 CV candidates are new discoveries. The BaggingTopPush and the Random Forest algorithms are applied to the Fifth Data Release (DR5) of LAMOST to retrieve CVs with strong emission lines and with broad absorption lines respectively. Based on spectroscopic classification, 134 dwarf novae, 41 nova-like variables and 19 magnetic CVs are identified from the sample. In addition, 89 high--inclination systems and 33 CVs showing companion stars are recognized and discussed for their distinct spectral characteristics. Comparisons between CVs from LAMOST and from published catalogs are made in spatial and magnitude distribution, and the difference of their locus in Gaia color--absolute magnitude diagram (CaMD) are also investigated. More interestingly, for two dwarf novae observed through LAMOST and SDSS in different epoch, their spectra both in quiescence phase and during outburst are exhibited.