Studium atmosfér Be hvězd

Abstract

Be stars are a group of hot, massive, emission-line stars characterized by intense radiatively-driven stellar wind and extremely rapid rotation. The typical emission in the Balmer series arises in a thin equatorial disc around the star. The detailed structure and most of all origin of the disc are still unknown. The aim of this thesis is to give a thorough review of the main directions of research into the eld. We describe observational features that set Be stars apart from the rest of the B spectral class: Balmer emission, linear polarization, infrared excess and superionized resonance lines in the far UV range; also main physical characteristics of the underlying star, and variability. We discuss the so-called Be phenomenon - the unknown mechanism creating the emission-producing circumstellar disc in Be stars, and providine an overview of the most successful models attempting to explain the Be phenomenon. Finally we discuss the rotation law of the disc and its importance in placing a physical constraint on possible models for Be stars, and apply one of the examined rotation parameter nding methods.