Study Of Early-Type Emission-Line Stars In Different Evolutionary Phases

I will be presenting my recent work on early-type emission line stars in the main sequence (Classical

Be stars) and pre-main sequence phases (Herbig Ae/Be stars). The formation and dissipation of discs in

these systems is not clearly understood at present. Our study intend to address the mass accretion rates in

Herbig stars and mass-loss process in Classical Be stars. We have discovered a sample of 86 Herbig Be

stars in the Large Magellanic Cloud. This discovery is important since the number of confirmed Herbig Be

stars in the LMC is quite small. This sample has passed all the quality tests needed to classify them as

intermediate mass pre-main sequence stars, ie., (i) Hα emission, (ii) infrared excess (as estimated from

spectral energy distribution analysis) and (iii) presence of nebulosity (inferred from forbidden lines).

Further, the age and mass of the Herbig Be stars are estimated from pre-main sequence isochrones and

evolutionary tracks. This sample of Herbig stars is used to address the decade old problem whether Herbig

Be stars in the LMC are in fact more luminous than the Galactic candidates. 

I propose a program to study the mass accretion rates in Herbig Ae/Be stars, which is fundamental to

understand the disc structure in these systems. Further, a comparative analysis is done between the

sample of Galactic Herbig stars and the LMC candidates to understand the role of metallicity in determining

the structure and evolution of the discs. 

I will be discussing the proposed plan to monitor and conduct follow-up studies of Be/X-ray binaries using

TIRSPEC/HFOSC on HCT. Also, results from the mid-infrared studies of Classical Be stars using WISE data

will be presented. .