A Study of H$α$ Line Profile Variations in $β$ Lyr

Abstract

We examine over 160 archival H$α$ spectra from the Ritter Observatory for the interacting binary $β$~Lyr obtained between 1996 and 2000. The emission is characteristically double-peaked, but asymmetric, and with an absorption feature that is persistently blueshifted. Using a set of simplifying assumptions, phase varying emission line profiles are calculated for H$α$ formed entirely in a Keplerian disk, and separately for the line formed entirely from an off-center bipolar flow. However, a dynamic spectrum of the data indicate the blueshifted feature is not always present, and the data are even suggestive of a drift of the feature in velocity shift. We explore whether a circumbinary envelope, hot spot on the accretion disk, or accretion stream could explain the observations. While none are satisfactory, an accretion stream explanation is somewhat promising.

accepted to Astronomical Journal