Name: Anusha Ravikumar
Affiliation: University of Western Ontario
Conference ID : ASI2022_476
Title : Spectroscopic study of Classical Be stars using LAMOST DR5
Authors : R. Anusha, Blesson Mathew, Suman Bhattacharyya, Gourav Banerjee, B. Shridharan, R. Arun, Rose M. Seby, Aiswarya, Riya K. Wilson, S. Nidhi, Madhulan S. S.
Abstract Type: Poster
Abstract Category : Stars, ISM and Galaxy
Abstract : We report the analysis of the prominent emission features in a sample of 1088 Classical Be stars (CBe) using the Large sky Area Multi-Object fiber Spectroscopic Telescope (LAMOST) survey. We note that more than 70% of the stars in our sample are being characterized for the first time. Taking advantage of the large sample size, we anchor our analysis on the FeII, CaII emission lines, and the Balmer decrement as these spectral features are less explored in CBe stars. Our analysis shows that the FeII emission strength in CBe stars does not decrease towards cooler spectral sub-types as mentioned in earlier studies. For stars with multiple epochs of observation, we notice that FeII emission strength does not show notable variations unless the Hα emission strength varies by more than 20%. The CaII IRT emission strength does not show large variations with spectral type in our sample. We observe the CaII triplet line ratio to be 1:4:3 in contrary to the theoretically predicted ratio of 1:9:5. The Balmer decrement estimates of ~11% stars show a possible optically thick circumstellar disc. We also compare the decrement estimates to calculate the disc opacity in CBe stars. It has to be noted that this is the largest sample in which CaII IRT lines and the Balmer decrement properties are homogeneously analyzed. Interestingly, we notice that the incidence of Be stars peaks at spectral type B8 in our sample. We also explore the correlation of this distribution with the position in the Galaxy, metallicity, and age estimates.