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Title: Hunting for cataclysmic variables using H-alpha surveys
Author: Witham, Andrew Robert
ISNI:       0000 0001 3571 1492
Awarding Body: University of Southampton
Current Institution: University of Southampton
Date of Award: 2007
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This thesis describes the contributions made by the author to the IPHAS survey and its follow-up. The IPHAS survey is currently observing the northern Galactic Plane in Ha, r', and i', and the work presented here focuses primarily on the effort to construct a new, large and well-defined sample of cataclysmic variables (CVs) from the survey. I first investigate the properties of the known population ofCVs in IPHAS. A selection algorithm has been developed to pick out objects from the IPHAS photometry that display a clear Her excess. This has led to the recovery of::: 70 per cent of the known CVs as Ha emitters, roughly independent ofCV type and orbital period. The selection algorithm has been employed further to create a catalogue of Her excess objects, which is presented and analysed. The resulting catalogue contains 4869 Ha emitters. I present and analyse initial follow-up observations that are relevant to the construction ofa new CV sample. A series of long-slit spectroscopic observing runs has so far provided identification spectra of several hundred Ha emitters. A classification algorithm has been developed and used to assign spectral types to these sources. The majority are found to be early-type stars, whereas interacting binaries including CVs and symbiotic stars, make up a relatively small percentage of the emission line ~tar population. The ID spectroscopy taken so far has allowed the discovery of 11 new CV candidates. Additional time-resolved observations for 3 of these confirm their CV classification and provide estimates of their orbital periods. Overall, this thesis shows that IPHAS is capable of discovering a significant sample of CVs that should be largely free of the selection effects that have plagued previous surveys. Once a significant population has been discovered, it will be possible to test theories of binary evolution and CV population synthesis models.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available