Dr. Howell proposes an extensive observational and theoretical investigation of cataclysmic variable (CV) stars. CVs consist of a close pair of interacting stars in which the primary is a white dwarf accreting from a cooler normal main sequence star. Typical orbital periods are less than 12 hours. Such binary pairs are important because they provide an evolutionary bridge between some types of massive white dwarf stars that cannot easily result from normal single star evolution and supernova, often use as distance indicators to other galaxies because they are so bright. Since they are evolving rapidly, CVs also provide useful constraints on the white dwarfs masses, which are otherwise very difficult to determine, and on theoretical models of mass exchange in close binaries. Dr. Howell intends to greatly improve the observational coverage of fainter, shorter period CVs in order to test the hypothesis that short period CVs are in fact the most common type. The observations will also provide a robust test of theoretical models that predict that orbital periods reach a minimum at about 2 hours. Additional IR spectra obtained will yield important information on the physical characteristics of the thin accretion disks as well as the often hidden stellar components in fainter pairs. The observing facilities available at the University of Wyoming's Infrared Observatory (WIRO), Red Buttes Observatory (RBO) and University of Florida Rosemary Hill Observatory (RHO) will provide most of the photometric light curves and infrared spectroscopy.
