Eclipsing Binaries and Period Changes in the SuperWASP Archive

Lohr, Marcus (2015). Eclipsing Binaries and Period Changes in the SuperWASP Archive. PhD thesis The Open University.

DOI: https://doi.org/10.21954/ou.ro.0000a668

Abstract

The aim of this research project has been to investigate eclipsing binaries using archival data from the SuperWASP (Wide Angle Search for Planets) survey, and specifically to search for evidence of orbital period variations. The short cadence and long time base of SuperWASP light curves make them highly suitable for variable star research of many kinds, and the size of the database (~30 million objects) allows for the discovery and study of rare objects and stellar types.

Techniques optimized for analyzing SuperWASP data were developed over the course of the research, using custom IDL codes, and proved successful in measuring orbital periods and detecting period changes in real and synthetic test data. Employing these, original results were achieved in a range of areas. A sample of 143 eclipsing binary candidates were found with periods close to the short-period limit of the period distribution for main sequence binaries, which shed light on the likely cause of the limit. Significant period increases and decreases were detected in many of these, and several individual objects were followed up with spectroscopic and multicolour photometric observations, by ourselves and others, to allow confirmation of their binary nature and modelling to determine system and component parameters. Amongst these were a probable close triple system containing a low-mass contact binary, and a doubly-eclipsing quintuple system, only the sixth known of its kind. Eleven post-common-envelope eclipsing binaries were also studied for evidence of period changes, potentially associated with circumbinary planets; our findings add to the ongoing debate on the reality and stability of planetary systems in such environments. Finally, we used our findings on period changes in ~14000 candidate SuperWASP eclipsing binaries of all types to estimate the higher-order multiplicity fraction of such systems.

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