Modeling the binary central stars of the planetary nebulae Sp 1 and NGC 6337

Current estimates of the impact of close binary stars on the shaping and ejection of common envelopes and planetary nebulae include a number of systems for which little published data and/or no binary parameters exist in the literature. Only six of the approximately 45 currently catalogued binary systems have been well studied. With the current emphasis in planetary nebula research on determining the role of binarity in the planetary nebula process, and the importance of post common envelope systems in our understanding of many important astrophysical systems it is imperative that we understand as well as possible the small number of detected binary systems. We present light curves, spectra, and radial velocity curves for the close binary central stars of the planetary nebulae Sp 1 and NGC 6337. Both systems are low inclination irradiated binaries with a cool main sequence companion to the hot central star. We have used the Wilson-Devinney code to place strong constraints on the physical parameters of each system. We relate our results to larger issues such as the ejection and formation of planetary nebulae, close binary evolution, and common envelope evolution.