Indirect Imaging of Cataclysmic Variable Stars

Abstract

Cataclysmic variable stars (CVs) are compact binaries consisting of a white dwarf, a late main-sequence star and an accretion structure. Due to their distance, their apparent sizes are too small to allow direct imaging. Their short orbital periods of 1 to 10 hours allow the usage of indirect imaging or mapping methods which base on different observing angles to the observed object.I developed, analyzed, and applied three new mapping methods for CVs. The first two of these basically do a forward synthesis of light curves of magnetic systems. The third method uses spectra of either accretion disk or magnetic systems. These synthetic data are modified until the light curves or spectra fit to the observed data. The fitting algorithm uses an evolution strategy for the optimization process.My eclipse mapping method for magnitic CVs is applied to UV data of UZ For taken with the Hubble Space Telescope. I extend the eclipse mapping method to use data taken over a full binary star orbit. This approach is applied to optical data of another magnetic CV system, HU Aqr. For the third mapping method add spectral resolution as a second dimension to the dataset. I apply the spectral fitting method, which I dubbed "orbital mapping", to two non-magnetic CVs: With data of the newly discovered HS0455+83, an SW Sex system, I try to substantiate the stream overflow model of this subtype of CVs. The SU UMa System V436 Cen is analyzed for the radial intensity gradient in the accretion disk and absorption signatures which cannot be explained by a simple disk model.A short description of the CVcat project - a database on CVs - is given in the appendix.