New Oe Stars in LAMOST DR5

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 that 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.