T. S. Poole
A multi-wavelength study of cataclysmic variable stars
2004 (supervisor: K. O. Mason)
This thesis investigates the properties of two cataclysmic variables which
have previously been considered to be non-magnetic systems. The goal of
this work is to constrain the component star masses and other physical
parameters of these systems using multi-wavelength observations.
I carry out spectroscopic studies on the eclipsing nova-like system RW Tri
in the ultraviolet, far red, and near infrared. I produce a simple
absorption model to show that one possible scenario for the origin of
ultraviolet narrow absorption features, seen in Hubble Space
Telescope observations, is a ring-like structure with height above the
orbital plane, centred on the primary star. I re-analyse far red data
from the Issac Newton Telescope, using the tomographic technique of
‘skew-mapping’ to obtain the radial velocity amplitude of the secondary
star. I have made new observations of RW Tri in the near infrared using
the United Kingdom Infra-Red Telescope to determine the accuracy of
the secondary star radial velocity amplitude. The measured secondary star
radial velocity has been combined with ultraviolet absorption line
analysis and existing optical emission line data, to calculate the mass
ratio, and hence the mass of the component stars. The rotational velocity
of the secondary star has also been obtained from the infrared
observations, and combined with the radial velocity of the secondary star
to calculate more reliable component star masses.
OY Car, an eclipsing dwarf nova, was observed at X-ray wavelengths using
XMM-Newton. I study the light curves, and measure the extent of
the boundary layer in the system. I also observe significant
quasi-sinusoidal variations with an underlying periodicity of 2233
seconds, which may be the spin period of the white dwarf primary star.
These results imply that OY Car may be weakly magnetic, and could
therefore belong to a new class of intermediate polars below the period
gap. Investigations of the eclipse profile lead to an estimate of the
component star masses.