Contributed Talk - Splinter Stellar
Friday, 25 September 2020, 14:23 (virtual room M)
Post-common-envelope binary central star in planetary nebulae
Henri M.J. Boffin, David Jones, et al.
ESO, Germany; IAC & Universidad de La Laguna, Spain
A significant fraction of planetary nebulae (PNe) are the product of interactions in close binary stars. However, despite their clear importance in understanding PNe, the nature of those binary interactions and, in particular, the common envelope phase is still rather poorly understood. A key step towards furthering our understanding of these systems is to observationally constrain their parameters such that they can be used to confront models. We here present the discovery and characterisation of the post-common-envelope central star system in PN G283.7−05.1, comprising a highly-irradiated, M-type main-sequence star in a 5.9 hour orbit with a hot pre-white-dwarf. The nebular progenitor is found to have a particularly low mass of around 0.4 Msun, making PN G283.7−05.1 one of only a handful of candidate planetary nebulae to be the product of a common-envelope event while still on the red giant branch. We further present a detailed study of the binary central star of the planetary nebula ETHOS 1, which reveals the binary to comprise a very hot pre-white-dwarf with an M-type main-sequence companion. A good fit to the observations was found with a companion that follows expected mass-temperature-radius relationships for low-mass stars, indicating that despite being highly irradiated by the central star it is not significantly hotter or larger than a typical star ofthe same mass. We derive a binary inclination in agreement with that of the nebula as determined by spatio-kinematic modelling. This makes ETHOS 1 the ninth post-common-envelope planetary nebula in which the binary orbital and nebular symmetry axes have been shown to be aligned, with as yet no known counter-examples.