Spectroscopic study of Herbig Ae/Be stars in the Galactic anti-centre region from LAMOST DR5

Abstract

ABSTRACT We study a sample of 119 Herbig Ae/Be stars in the Galactic anti-centre direction using the spectroscopic data from large sky area multi-object fiber spectroscopic telescope survey program. Emission lines of hydrogen belonging to the Balmer and Paschen series, and metallic lines of species such as Fe ii, O i, Ca ii triplet are identified. A moderate correlation is observed between the emission strengths of  Hα and Fe ii 5169 Å, suggesting a possible common emission region for Fe ii lines and one of the components of  Hα. We explored a technique for the extinction correction of the HAeBe stars using diffuse interstellar bands present in the spectrum. We estimated the stellar parameters such as age and mass of these HAeBe stars, which are found to be in the range 0.1–10 Myr and 1.5–10 M ⊙, respectively. We found that the mass accretion rate of the HAeBe stars in the Galactic anti-centre direction follows the relation $\dot{M}_{\mathrm{ acc}}$ ∝ $M_{*}^{3.12^{+0.21}_{-0.34}}$, which is similar to the relation derived for HAeBe stars in other regions of the Galaxy. The mass accretion rate of HAeBe stars is found to have a functional form of $\dot{M}_{\mathrm{ acc}} \propto t^{-1.1\, \pm\, 0.2}$ with age, in agreement with previous studies.