A statistical analysis of the emission line ratios in cataclysmic variables

Abstract

A statistical analysis of the emission lines in cataclysmic variables and a catalogue of all recorded H-alpha, H-beta, H-gamma, H-delta, He I 4471 A, and He II 4686 A emission lines are presented. A strong correlation is found between H-delta/H-beta and H-gamma/H-beta, although no correlation is found between H-alpha/H-beta and other Balmer ratios. This correlation is explained in terms of simple LTE calculations. It is shown that the intensity of He I 4471 A increases with H-lambda/H-beta. This relationship is not found in LTE accretion disk models. No correlation is found for He II 4686 A. The observations do not support the anticorrelation between H-alpha/H-beta and H-lambda/H-beta indicated by the LTE calculations.