Theoretical Studies of Cataclysmic Variables

In order to understand the observational biases that may exist as well as the true nature of the usually ignored secondary stars in interacting binaries, Steve has been actively working on theoretical modeling and evolutionary mapping of binary systems. Beginning 4 years ago with the first detailed work on the evolution of low mass, ultra-short systems (the TOADs), and continuing today with current work focusing on the secondary star itself, this theoretical effort has made much progress in our understanding of short-period, low mass binaries.

Shown here is a few recent results which provide a theoretical 3-D map of the orbital period (x-axis in units of orbital period * 100), vs. a few parameters for the secondary star. the intensity of the color scale indicates both a higher concentration of system present as well as a time tag for them during their evolution.

Theoretical results of the Mass Transfer Rate vs. Orbital Period for cataclysmic variables. The color scale is a log scale representation of the total number of CVs present in the Galaxy at the present epoch.
Theoretical results of the Secondary Star Mass vs. Orbital Period for cataclysmic variables. The color scale is a log scale representation of the total number of CVs present in the Galaxy at the present epoch.

Mass histograms for cataclysmic variables as a function of various orbital period ranges. Note the different y-scales and the lack of low mass WD's at long orbital periods.