A model of the dwarf nova WX Cet

Abstract

We analyse time-resolved spectroscopy of WX Cet, a dwarf nova of the WZ Sge class, by means of a dynamical model based on the measured K 1 and using the superhump period excess e to constrain the mass ratio q of this CB. From time resolved spectroscopy of Thorstensen et al. we determine orbital amplitude K 1 and separation 2V d of the disk emission lines as well as the S-wave amplitude A s and relative phase a of the hot spot. Our dynamical analysis, following Smak's inclination independent solution for WZ Sge, yields rather high q, hardly compatible with the superhump resonance condition within the accretion disc. Rejecting K 1 as affected by tidal and/or stream effects, we follow Patterson and determine q = 0.085 from q - ∈ relation based on superhump dynamics. In this way we obtain likely masses of the components M 1 = 0.55 ′ 0.15 M O . and M 2 = 0.047 ′ 0.013 M O .. From this result we argue that despite similarities to WZ Sge, WX Cet with its relatively massive secondary represents an earlier stage of mass transfer in a cataclysmic binary than WZ Sge.