The Value-added Catalog of OB Stars in LAMOST DR7

TL;DR

This paper updates the catalog of OB stars using LAMOST DR7 data, improving selection criteria, classifying spectral types automatically, and identifying new Be-type stars, thereby aiding Milky Way studies.

Contribution

The study introduces a revised OB star catalog with enhanced completeness and includes a new automatic classification method and identification of Be-type stars.

Findings

Identified 37,778 OB star spectra, including 3,827 new stars.

Improved selection criteria enhance late B-type star completeness.

Found 10.9% of OB stars are Be-type, consistent with previous studies.

Abstract

In this work, we update the catalog of OB stars based on the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) data release 7 and modified the OB stars selection criterion the spectral line indices space. The new catalog includes 37,778 spectra of 27,643 OB stars, of which 3827 OB stars are newly identified. The spectral subclasses of 27,643 OB stars are obtained using the automatic classification code MKCLASS. We find that the modified OB star selection criteria can better improve the completeness of late B-type stars by analyzing their spectral classification results given by MKCLASS. We also identify 3006 Be-type stars or candidates by examining the Balmer lines in their spectra and find that the frequency of our Be-type stars (10.9\%) is consistent with previous results. The spatial distribution of OB stars indicates that they are mainly located in the Galactic disk. This new catalog of OB stars will provide valuable data for studying the structure and evolution of the Milky Way.