Be stars: Messengers of stellar disk physics

Be stars are massive stars with the presence of material around them in the form of a disk. The formation mechanism of these disks, known as the Be phenomenon, is still poorly understood. Be stars provide excel- lent opportunity to study circumstellar disks. Spectra of Be stars show interesting emission lines of different elements such as hydrogen, helium, iron, oxygen and calcium, silicon, magnesium, nitrogen on rare occasion. Spectroscopic studies of these emission lines provide important insight about the geometry and kinematics of the disk. In this article, we provide an introduction to the various observable properties of Be stars, effect of metallicity on those properties and discuss the major breakthroughs, till date in Be star research. We also summarise the research contribution to this area, by the team at the CHRIST (Deemed to be University).