New Oe stars in LAMOST DR5

TL;DR

This paper reports the discovery of six new Oe stars and four B0e stars in LAMOST DR5, expanding the known sample and providing insights into emission line variability and spectral features of these rare stars.

Contribution

It presents the identification of new early-type Oe and B0e stars in LAMOST DR5, significantly increasing the known sample and analyzing their spectral variability.

Findings

Discovered 6 new Oe stars and 4 B0e stars in LAMOST DR5.

Observed emission line variability and phase lags in Oe stars.

Identified an unusual O4.5 star with variable emission features.

Abstract

Stars of spectral type Oe are very rare. To date, only 13 Oe stars have been identified within our Galaxy. In this paper, we present six new Oe stars and four new B0e stars found in LAMOST DR5. Repeated spectral observations of the same Oe stars show some emission line variability. The H$\beta$ emission of TYC 4801-17-1 shows rapid V/R variation. Phase lags in the V/R ratio of TYC 4801-17-1 spectra are also seen. We found the unusual O4.5 star RL 128 is an Oe star with variable H$\alpha$ intensity and its Ca II triplet emission appears when H$\alpha$ emission reaches maximum intensity. These newly identified early type Oe and B0e stars significantly increase the known sample.