Identification of New Classical Be Stars from the LAMOST Medium Resolution Survey

Abstract

Be stars are B-type main-sequence stars that display broad Balmer emission lines in their spectra. Identification of the Be population is essential to further examine the formation and evolutionary models. We report the detection of classical Be (CBe) stars from observations with the Large sky Area Multi-Object fiber Spectroscopic Telescope Medium Resolution Survey Data Release 7 (LAMOST MRS DR7). We used a deep convolutional neural network, ResNet, with an 18 layer module to examine the morphology of the Hα profile. We identified 1162 candidate Be stars from the collection of 2,260,387 spectra for 789,918 stars in the database. The ResNet network achieves a Be-star classification accuracy of 99.5%. Among the detections, 151 of these are prior known Be stars crossmatched from the literature. By applying a three-step test, we identified 183 new CBe stars. We find that 41 CBe stars are members of known open clusters. Based on an investigation of the kinematics of the identified CBe stars from the Gaia EDR3 astrometric solutions, we identified 16 new runaways. These new identifications will provide a reference for future follow-ups to further investigate their physical properties.