Browsing by Subject "Dwarf novae"

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    High-speed photometry of SDSS J013701.06 − 091234.9
    (2004) Pretorius, M L; Woudt, P A; Warner, B; Bolt, G; Patterson, J; Armstrong, E
    We present high speed photometry of the Sloan Digital Sky Survey cataclysmic variable SDSS J013701.06-091234.9 in quiescence and during its 2003 December superoutburst. The orbital modulation at 79.71pm0.01 min is double humped; the superhump period is 81.702pm0.007 min. Towards the end of the outburst late superhumps with a period of 81.29pm0.01 min were observed. We argue that this is a system of very low mass transfer rate, and that it probably has a long outburst interval.
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    QPOs in cataclysmic variables and in X-ray binaries
    (2005) Kluźniak, W; Lasota, J-P; Abramowicz, M A; Warner, B
    Recent observations, reported by Warner and Woudt, of Dwarf Nova Oscillations (DNOs) exhibiting frequency drift, period doubling, and 1:2:3 harmonic structure, can be understood as disc oscillations that are excited by perturbations at the spin frequency of the white dwarf or of its equatorial layers. Similar quasi-periodic disc oscillations in black hole low-mass X-ray binary (LMXB) transients in a 2:3 frequency ratio show no evidence of frequency drift and correspond to two separate modes of disc oscillation excited by an internal resonance. Just as no effects of general relativity play a role in white dwarf DNOs, no stellar surface or magnetic field effects need be invoked to explain the black hole QPOs.