Spectroscopic Study Of Selected Be Stars In Our Galaxy

Spectroscopic Study Of Selected Be Stars In Our Galaxy

The optical spectroscopic monitoring observation of two Be stars namely 4 Hercules and 88 Hercules was observed with 1.02m telescope at the VBO, Tamil Nadu, India over a period of six months. The spectra were reduced using standard routines in IRAF. The equivalent width of the lines were identified have been measured. The line profile variability exhibited by H? H?and HeI lines are studied to understand the emission mechanism in the Classical Be-stars. The properties of the process can be well constrained, leaving only few options, most importantly, but not exclusively, non-radial pulsation and small scale magnetic fields. In different stars different processes may be acting. This is not only true for the disk structure, but as well for its variability, both cyclic and secular. Be stars, at lower metallicities, seem more common and more rapidly rotating. The Be phenomenon, linked with one or more mass ejection processes, acts on top of a rotation rate of about 75% of critical or above. In this work, first the definition of Be-stars is contrasted to similar classes, and common observables obtaind for Be-stars are introduced and the respective formation mechanism explained. The current state of knowledge concerning the central stars as non-radially pulsating objects and non-magnetic stars, as far as it concerns large scale. The weak magnetic fields remain possible, but are of yet unproven. In this dissertation Chapter 1 discusses the features of Be- stars and reviewed the progress made in understanding Be-stars in the recent past. Chapter 2 discusses the literature review. Chapter 3 describes the methodology carried out to study the objective. Chapter 4 explains the result and analysis part of the research. Chapter 5 is about the conclusions.

Mathew Amita

Department of Physics