Affiliation: CHRIST (Deemed to be University), Bangalore
Conference ID : ASI2022_307
Title : Herbig Ae/Be stars in the Galactic anti-center direction
Authors : Nidhi Sabu, Blesson Mathew, Shridharan Baskaran, Arun Roy, Anusha R, Sreeja S Kartha
Abstract Type: Poster
Abstract Category : Stars, ISM and Galaxy
Abstract : Herbig Ae/Be stars are intermediate mass pre-main sequence stars. We identified 119 Herbig Ae/Be stars spread across the Galactic anti-center direction using the LAMOST DR5. Among the sample, 80 stars are new detections, which significantly increases the known Herbig Ae/Be stars in the Galaxy. By visual inspection, we identified Hα, Caii triplet, Feii, Hei, and Diffused Interstellar Bands (DIB) in the sample spectra. The correlation between the emission strength of Hα and Feii lines is studied. Stellar parameters such as spectral type, spectral index, age, and mass are determined using a homogeneous approach. We calculated the extinction of the HAeBe stars independently using DIBs present in the spectra. The mass accretion rates of HAeBe stars are estimated using the accretion tracer, Hα emission line, and found to be within a range of 10^−6 - 10^−9 Myr^−1. We find a clear trend of mass accretion rates increasing as a function of stellar mass and obtained a power-law relationship of Macc∝M∗^3.08. Also, the dependency between mass accretion rate and age is obtained in the form of Macc∝t^(−1.26±0.24), which confirms that younger stars have higher mass accretion rates. In addition, we used the LAMOST AFGK value-added catalog, to estimate the metallicity values for 110 HAeBe stars, which is found to be in the range of -0.7 < [Fe/H] < 0.14. We found lower metallicity values for stars towards the outer part of the Galaxy with a discontinuity near Galactocentric radius of 11 kpc. This suggests that the outer disk of the Galaxy may have experienced a different evolutionary path, which explains the variation in metallicity values of the HAeBe stars across the Galactic anti-center direction.