Accretion disk winds in dwarf novae

Abstract

It is well known that the International Ultraviolet Explorer observations of high-excitation P Cygni profiles of C IV and S IV lines provide direct evidence for winds in cataclysmic variables which reach speeds of similar to 5000 km s(-1). We present in this paper our analysis of P Cygni profile for C IV line in seven dwarf novae based on 195 low-resolution IUE spectra. This work aims to do two things: i) to examine them in terms of wind properties, and ii) to seek time dependence of the lines indicating departure from axial symmetry in the outflow and/or disk and changes in the wind ionisation and/or mass loss rate. We infer the optical depth of C IV, the column density and the number density of absorbing and scattering ions in the region where the wind ionized.