Long-term Spectroscopic and Photometric Monitoring of Bright Interacting Algol-type Binary Stars

Binary stars have long been used as natural laboratories for studying such fundamental stellar properties as mass. Interacting binaries allow us to examine more complicated aspects such as mass flow between stars, accretion processes, magnetic fields, and stellar mergers. Algol-type interacting binary stars -- consisting of a cool giant or sub-giant donating mass to a much hotter, less evolved, and more massive main-sequence companion -- undergo steady mass transfer and have been used to measure mass transfer rates and to test stellar evolution theories. The method of back-projection Doppler tomography has also been applied to interacting Algols and has produced indirect velocity-space images of the accretion structures (gas streams, accretion disks, etc.) derived from spectroscopic observations of hydrogen and helium emission lines. The accretion structures in several Algol systems have actually been observed to change between disk-like states and stream-like states on timescales as short as several orbital cycles (Richards et al., 2014). Presented here are the first results from a project aimed at studying bright interacting Algol systems with simultaneous mid-resolution (11,000<R<18,000) echelle spectroscopy and multi-band photometry. The observatory is located on the campus of Kutztown University in Pennsylvania and is best suited for objects brighter than 8th magnitude. These initial results include new observations and analyses of full-orbit radial velocity curves, Doppler images, and photometric light curves of U CrB, RW Tau, U Sge, and RZ Cas. The long-term goal of this project is to determine the periodicity of changes between stream-like and disk-like states over different temperature regimes, to identify the various accretion phenomena, and to extract their physical properties.