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NAM2012 - All Presentation Details

Record 739 of 756

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Period decrease in three SuperWASP eclipsing binary candidates near the short-period limit

Author: Marcus Lohr

Open University

Co-Authors: A.J.Norton (Open University)

Session: STA2: Binary Stars: Duplicity is Everywhere

Presentation type: Poster      Poster Session B   


W UMa-type variables are contact binaries with low-mass main sequence components. Their light curves exhibit continuous variation associated with the ellipsoidal Roche-lobe-filling components, and eclipses of similar depth due to a shared atmospheric envelope, concealing low mass ratios. Their orbital periods, typically of several hours, exhibit a lower limit around 0.22d. The reason for this is uncertain, but may be associated with a lower limit of primary mass and/or mass ratio, below which the stars rapidly inspiral and merge. Our research follows up the identification of 53 W UMa candidates near the short-period limit, by Norton et al. (2011), in SuperWASP archival data. Here, a three-part period search program confirmed the periods of all but nine objects as <20000s. Additionally, O-C diagrams were automatically constructed, indicating period decrease significant at more than 5σ in three objects. One system with a period of only 0.21d appears to be losing orbital period at a rate of about 0.3s/yr, suggesting a possible merger on a rapid timescale. Such objects can help understand W UMa evolution and the reason for the short-period limit. We are currently trying to model these systems to determine their parameters, and to identify further SuperWASP short-period eclipsing binaries.

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