Abstract

Contributed Talk - Splinter CloseBinaries   (MW-0250)

The first detached, double eclipsing, double lined, and double degenerate system inside a planetary nebula

Nicole Reindl
ZAH, Landessternwarte der Universität Heidelberg

Close binary central stars of planetary nebulae offer a unique window into the immediate aftermath of common-envelope (CE) evolution. In particular, systems that are both double eclipsing and double-lined provide rare opportunities to constrain stellar and orbital parameters with minimal model dependence. In this talk, we present a detailed study of the nucleus of Pa 13 (P = 0.3988 d), identifying it as a rare double-degenerate system of this kind. We combine phase-resolved spectroscopy with NLTE modeling, multiband light-curve analysis, and spectral energy distribution fitting to characterize the system. Both components are identified as hot pre-white dwarfs, with one being cooler and larger and the other hotter and more compact. We highlight evidence for a small but significant orbital eccentricity, placing Pa 13 among the very few post-CE systems where this has been measured. Overall, Pa 13 provides hitherto the strongest evidence that planetary nebulae can form around post-red giant branch stars. We conclude by discussing possible evolutionary pathways that could give rise to such a system.