The study of the cataclysmic variable SSS J122221.7-311525 in quiescence

Abstract

Cataclysmic variables are interacting binary stars. They are an interesting topic of study because of their short orbital periods and prominent accretion behaviour. According to the standard model of evolution, these systems evolve from longer to shorter orbital periods under the influence of stable mass-transfer caused by angular momentum loss. The donor star will eventually transform into a brown dwarf and cause the orbital periods to start increasing again. In this study I focused on the cataclysmic variable SSS J1222221.7-311525, a system with a suspected brown dwarf donor. The system has been quite extensively studied during a superoutburst phase. The aim of this thesis was to study the system during its quiescence period and hopefully find some direct evidence of the brown dwarf donor.

The study included three sets of spectroscopic data taken with the Very Large Telescope of the European Southern Observatory (ESO) during three different years and two sets of photometric data taken with the Nordic Optical Telescope and the Very Large Telescope in 2019.

Most interesting findings were done using Doppler tomography, in which the emission structures of the system were plotted into velocity maps. The observed structures showed unusual characteristics, the origins of which remain unclear. No direct sign of the donor were found. The radial velocity analysis let us determine system parameters for the system. Spectral energy distribution showed no sign of a main-sequence star and therefore supports the findings of the earlier studies.