Post-common envelope pre-cataclysmic and cataclysmic variable binaries
Sing, David K.
Thesis or dissertation
University of Arizona
Extensive photometric and spectroscopic observations have been obtained for the binary HS1136+6646, a newly formed post-common envelope binary system containing a hot ∼DAO.5 primary and a highly irradiated secondary. H1136+6646 is the most extreme example yet of a class of short period systems containing a hot H-rich white dwarf with a K-M companion. An orbital period of 0.83607 ± 0.00003 days has been determined through the phasing of radial velocities, emission line equivalent widths, and photometric measurements spanning a range of 24 months. Radial velocity measurements yield an amplitude of KWD = 69 ±2 km s−1 for the white dwarf and KK7V = 115 ± 1 km s−1 for the secondary star. Photometric measurements revealed a low amplitude modulation with a period of 234 minutes, associated with the rotation of the white dwarf. The white dwarf is estimated to have an effective temperature and gravity of ∼100,000 K and log g∼8.29 respectively, indicating the binary system is the second earliest post-CE objects known, having an age around 6.4x105 years. Indications are that the secondary star is overly luminous for its mass. I also present FUSE observations of the magnetic cataclysmic variable V405 Aurigae. Together with four other DQ Her type binaries, V405 Aur forms a small subclass of intermediate polars which are likely to evolve into low magnetic field strength polars. The FUSE spectrum exhibits broad O VI and C III emission-lines as well as a narrow O VI emission-line component which likely forms near the white dwarf surface in an optically thin gas. Radial velocity measurements restrict any orbital modulation to a very low amplitude (KWD =2.5 ± 0.5 km s−1) indicating that the binary system is at low inclination. Recent photometric and spectroscopic observations have revealed J0644+3344 to be a bright, deeply eclipsing cataclysmic variable binary with a 6.4648 ± 0.00024 hour period. Although the nature of the hot component is not presently clear, J0644+3344 is one of the brightest eclipsing nova-like cataclysmic variable system yet. As such, the possibility exists for an unambiguous determination of the masses and temperatures of both components in future studies.