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J. K. Cannizzo (UMBC), N. Gehrels (NASA/GSFC), J. A. Mattei (AAVSO)
We examine the long term AAVSO light curve of the dwarf nova U Geminorum from 1908 to 2002 which consists of over 51,000 individual observations. We examine long terms trends in the outburst properties along the lines of previous analyses of SS Cygni. U Gem has a significantly shorter orbital period (4.2 hrs versus 6,6 hrs), and the fraction of time spent in outburst is also significantly less (~0.1 versus ~0.25). The analysis is somewhat complicated for U Gem given that the system lies in the plane of the ecliptic and therefore has significant sun gaps. Nevertheless one may circumvent this to some extent by utilizing ``sliding windows'' centered on a given point of interest in the light curve, and defining a quality factor associated with that point which is based on how much, if any, of the data in that window is contained within a sun gap.
We present frequency histogram distributions for various properties associated with the outbursts as well as correlations between the different parameters, and discuss the constraints on the physics of accretion disks, in particular the accretion disk limit cycle instability.
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Bulletin of the American Astronomical Society, 34
© 2002. The American Astronomical Soceity.