WOLF-RAYET CENTRAL STARS AND THE BINARY EVOLUTION CHANNEL

摘要

Single star evolutionary calculations have recently succeeded in reproducing the composition of the hydrogen-deficient Wolf-Rayet (WR) central stars of planetary nebula (PN). However, the latest infra-red observations, made it clear that the single star scenario is at odds with the properties of the dust surrounding many WR central stars. Binarity, on the other hand, can potentially explain the infra-red observations, as well as offer a viable way of depleting a star of its outer, H-rich envelope. In this work we expose two binary scenarios first discussed in connection to WR central stars by De Marco & Soker. In the first, a close binary system results in back-flowing material and ultimately in a H-deficient central star of PN. This scenario, is invoked to explain the [WC10] central star CPD-56°8032 and its dusty disk. The second scenario envisages that the majority of WR central stars are the result of a merger with a low mass companion during the Asymptotic Giant Branch (AGB) phase. This scenario is partly tested here, by 3-dimensional hydrodynamical models, which simulate the common envelope phase between 0.1 and 0.2-M_⊙ companions and an AGB star at the first and tenth thermal pulse.