Hydrogen Deficient Binaries - Photometry and Orbits

Photometric and spectroscopic observations of the extremely hydrogen-deficient binaries υ Sgr, LSS 4300 and CPD-58°2721 have been obtained at Mt. John University Observatory (MJUO) to examine the nature of these systems.

The photometric data do not confirm that υ Sgr is an eclipsing system. These data are also used to examine long-term light and colour variations in the star, which show some longer-term periods of brightness variations which may be indicative of stellar activity in the primary star of this system. The spectroscopic data yield sets of orbital parameters for υ Sgr and LSS 4300. For υ Sgr, these are consistent with the orbital parameters obtained earlier this century. Comparisons are also made between the Hoc profiles of the three systems and phase-related Hα profile variations in υ Sgr discussed. All the observational data provide confirmation for a model involving supersonic mass exchange between the components of the binary system.