Study Of Herbig Ae/Be Stars In The LAMOST DR7 Medium-resolution Spectral Library

Herbig Ae/Be stars are intermediate-mass pre-main sequence stars,typically between 2-10M_⊙in mass and 1-10 Myr in age.Hydrogen combustion has not yet occurred inside Herbig Ae/Be stars.Herbig Ae/Be stars are a major sample for studying the early evolution of intermediate-mass stars.Herbig Ae/Be stars can help study the early evolution of intermediate-mass stars and explore the various physico-chemical changes that occurred during their evolution.The accretion disk of Herbig Ae/Be stars can be used to study the evolution of the interstellar medium and the formation of superior planet.As a class of young stars,Herbig Ae/Be stars are ideal objects for studying the initial mass function of star-forming regions.Only a few hundred Herbig Ae/Be stars are known,and this work aims to expand the sample size of Herbig Ae/Be stars.Based on the characteristics of Herbig Ae/Be stars such as infrared excess,emission lines,this work identifies a total of 231 Herbig Ae/Be stars based on LAMOST DR7 medium-resolution spectral data,of which 210are newly identified.In this work,we determined the boundary conditions for screening Herbig Ae/Be stars based on their positions in the color-absolute magnitude and color-color diagrams,obtained 231 sample stars.For the 140 stars with a signal-to-noise ratio greater than 5,their effective temperatures were obtained according to the template matching method,and 155 of the 231 stars have emission lines.The present work classifies the emission lines according to their morphology into three categories,namely,single-peaked,double-peaked,and P Cygni,and the percentages are 53.5%、27.1%、19.4%,respectively.The SED(Spectral energy distribution)confirm the presence of infrared excess in all 231 stars,suggesting that these stars are surrounded by accretion disks.231 stars are distributed around the spiral arms,and most of them are located in the low galactic latitude region,and the spatial distribution indicates that these are young stars.The 231 Herbig Ae/Be stars found in this work coincide with the known positions of Herbig Ae/Be stars on the H-R diagrams,and these phenomenon prove the reliability of the Herbig Ae/Be stars selected in this work.