Marshall, George (2010) Optical transients in the WASP survey. PhD thesis, University of Warwick.

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Abstract

This thesis describes a search for transient phenomena using data from the
Wide Angle Search for Planets (WASP) observatories. With images taken of the
same region of sky every 15 minutes and a field-of-view of 974 degrees squared,
the WASP survey is ideal for identifying both short and long duration transients
to a limiting magnitude of 16 in V. A high cadence wide-field survey of this type
has not been carried out before so provides a different method of sampling variable
populations and has the potential to identify previously unknown phenomena.
An algorithm to carry out a full untargeted search of the database was developed,
tested and run on data from 2004, 2006, 2007 and 2008. False positives were
rejected based on their proximity to similar magnitude stars, the tightness of the
clustering of detections in sky coordinates, the focus of the images and the number
of corroborating detections.
Overall, 44 cataclysmic variable candidates, 144 extreme flare candidates, 63
variable star candidates and 57 transients of unknown type were identified. The cataclysmic
variable candidates showed similarities to the currently known population
although some selection effects were uncovered. Of particular note were two new WZ
Sge systems, an eclipsing system with a period of 540 minutes and an object with
an M-star spectrum and broad Balmer lines but no visible white dwarf. The flares
are some of the largest ever observed on M-type stars. The largest of these released
~1035erg in the V-band alone. A candidate flare was also identified on a G-type
star releasing 1.6×1037erg in the V-band. Alternatively, it may be unrelated to the
G-star and could be a gamma ray burst or similar transient without a persistent
counterpart. A known supernova and two known novae were also identified.

Item Type:	Thesis (PhD)
Subjects:	Q Science > QB Astronomy
Library of Congress Subject Headings (LCSH):	Astronomy, Cataclysmic variable stars, Flare stars, Variable stars
Official Date:	September 2010
Dates:	Date Event September 2010 Submitted
Institution:	University of Warwick
Theses Department:	Department of Physics
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Wheatley, Peter J.
Extent:	xix, 274 leaves : ill., charts
Language:	eng

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