Various Types of Hα Emissions and Absorptions in Be/Shell Stars

Abstract

Among the Be stars, one distinguishes two types of spectra. The term Be/Shell used here is to designate the set of stars showing spectra of either of these two types: (i) Be spectrum and (ii) Be shell spectrum. In the Be spectrum, emission line either shows no reversal or a more or less central reversal. In the Be shell spectrum, Balmer lines and singly ionized lines exhibit narrow and deep absorption core, which may or may not be broadened by emission wings. In the present investigation we are reporting the spectroscopic observations of 14 Be/shell stars. The Hα line profiles of different stars possess various shapes. Most of the Be/shell stars exhibit very strong single peaked emission at Hα line. Four stars show strong double peaked asymmetrical Hα emission. Two of these programme stars display asymmetrical deep broad absorption with shallow limb towards the long ward wavelength. Other two objects show strong central absorption with two emission components. From the line profiles we have also measured the parameters like: equivalent width (W) and Ip/Ic ratio.