2013/05/31 by Yoji Osaki, Taichi Kato · 1 citation
Physics and Astronomy · #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Astrophysics and Star Formation Studies #Cataclysmic variable star #Dwarf nova #Light curve #Physics #RADIUS #Stars #Stellar, planetary, and galactic studies #Variation (astronomy) #White dwarf #astro-ph.SR
paper · pdf · doi:10.1093/pasj/65.5.95
26 pages, 14 figures, accepted for publication in PASJ, minor corrections
arxiv created 2013/09/13 · openalex publication_date 2013/10/25 · arxiv updated 2015/06/16 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Abstract We have studied the short-cadence Kepler public light curves of two SU UMa stars, V344 Lyr and V1504 Cyg, extending over a period of more than two years by using power spectral analysis. We determined the orbital period of V344 Lyr to be Porb = 0.087903(1)d. We also reanalyzed the frequency variation of the negative superhump in a complete supercycle of V1504 Cyg with additional data of the O – C diagram, confirming that its characteristic variation is in accordance with the thermal-tidal instability model. We present a new two-dimensional period analysis based on a new method of a least absolute shrinkage and selection operator (Lasso). The new method gives very sharp peaks in the power spectra, and it is very useful for studying the frequency variation in cataclysmic variable stars. We have analyzed simultaneous frequency variations of the positive and negative superhumps. If they are appropriately converted, it is found that they vary in unison, indicating that they represent a disk-radius variation. We have also studied the frequency (or period) variations of positive superhumps during superoutbursts. These variations can be understood in a qualitative way by combining the disk-radius variation and the variation of pressure effects during a superoutburst. A sudden excitation of oscillation with a frequency range near to the negative superhump (which we call “impulsive negative superhump”) was observed in the descending branch of several outbursts of V344 Lyr. These events seem to have occurred just prior to the next superoutburst, and to act as a “lead” of the impending superoutburst.