High-resolution IUE spectroscopy of fast winds from cataclysmic variables

Abstract

The winds from six dwarf novae and four nova-like cataclysmic variables are studied using 31 high-resolution IUE spectra. The data provide details on the time- and phase-averaged nature of disc-driven outflows, which are diagnosed via the presence of P Cygni-like and extended absorption profiles due to the C IV, N V and Si IV resonance line doublets, and He II lambda 1640. The profiles are parametrized using measures of the absorption and emission velocities, widths and strengths. The maximum wind velocity can exceed -4000 km s(-1), although the absorption maximum (minimum flux) typically occurs at similar to 20 per cent of the shortward profile edge. Optical depth and velocity structure is identified in the absorption troughs which may indicate inhomogeneities in the outflows. The relative ion behaviour and the respective contributions to the emission profiles of the inner disc and wind are discussed. Synthesized model profiles are used to estimate the products of mass-loss rate and C3+ ion fractions.