V344 Lyrae: A Touchtone SU UMa Cataclysmic Variable in the Kepler Field

• Published in: NASA Center for AeroSpace Information (CASI). Misc. Resources
• Main Authors: Smale, Alan P, Wood, Matt A, Still, Martin D, Howell, Steve B, Cannizzo, John K
• Format: Web Resource
• Language: English
• Published: Hampton NASA/Langley Research Center 01.01.2012
• Subjects: Accretion disks; Amplitudes; Bright spots; Cataclysmic variables; Dwarf novae; Dwarf stars; Flexing; Light curve; Orbits; Outbursts; Superhumps (astronomy)

We report on the analysis of the Kepler short-cadence (SC) light curve of V344 Lyr obtained during 2009 June 20 through 2010 Mar 19 (Q2-Q4). The system is an SU UMa star showing dwarf nova outbursts and superoutbursts, and promises to be a touchstone for CV studies for the foreseeable future. The system displays both positive and negative super humps with periods of 2.20 and 2.06-hr, respectively, and we identify an orbital period of 2.11-hr. The positive super humps have a maximum amplitude of approximately 0.025-mag, the negative super humps a maximum amplitude of approximately 0.8 mag, and the orbital period at quiescence has an amplitude of approximately 0.025 mag. The quality of the Kepler data is such that we can test vigorously the models for accretion disk dynamics that have been emerging in the past several years. The SC data for V344 Lyr are consistent with the model that two physical sources yield positive superhumps: early in the superoutburst. the superhump signal is generated by viscous dissipation within the periodically flexing disk. but late in the superoutburst, the signal is generated as the accretion stream bright spot sweeps around the rim of the non-axisymmetric disk. The disk super humps are roughly anti-phased with the stream/late superhumps. The V344 Lyr data also reveal negative super humps arising from accretion onto a tilted disk precessing in the retrograde direction, and suggest that negative superhumps may appear during the decline of DN outbursts. The period of negative superhumps has a positive P(raised dot) in between outbursts.