Copy the page URI to the clipboard
Lott, David Andrew
(2004).
DOI: https://doi.org/10.21954/ou.ro.0000fa20
Abstract
The Wide Area Variability Survey (WAVS) project used the CFH12k mosaic camera as the world's largest time series photometer to obtain images of a 0.33 square degree galactic field with a time resolution of 3 minutes over 2 nights of observations. The main aim of the WAYS project was to try and differentiate between the current competing models of cataclysmic variable (CV) population and evolution by obtaining an unbiased sample using a characteristic that all known CVs exhibit. All CVs show 'flickering' in their lightcurves, that is stochastic variations in luminosity with an amplitude of tenths of a magnitude on timescales of minutes to hours, and it is this characteristic that the WAYS project exploits. Lightcurves for each of the 52000 objects in the WAYS field were created and searched for variability. Spectroscopic observations using the Nordic Optical Telescope (NOT) were carried out to further investigate candidate objects.
In searching for variability on this timescale it was apparent that the WAYS project would also discover many variables of other types which may also be of great interest. Thus, the secondary goal of the WAYS project was to investigate these objects and obtain population statistics wherever possible.
This thesis gives an introduction to various types of stellar variability and covers the observable characteristics of CV s in some depth. Competing models of CV evolution are considered and the goals and strategies of the WAYS programme are outlined in more detail. An account of the process of obtaining high quality photometry and spectroscopy is given, both in the general case and in the more specific case applicable to the WAYS data and the methods used to search for variability in the WAYS sample are discussed.
The WAYS project has currently discovered 229 new variable objects and the lightcurves of these systems are presented in Appendices A to C. Some of these objects are discussed in detail, but for others accurate classification is difficult without more data, although a tentative classification is made.
Currently the WAYS project has not discovered any new CVs and the relevance of this null result is considered. However, 30 possible flickering objects have been identified.