Oral Presentation

Quasi-spherical spiral-shell pattern as a hint of binarity

Hyosun Kim (ASIAA/KASI) et al.

Binary companions play important roles in the evolved stellar stages.In particular, the evolution from a quasi-spherical geometry of the asymptotic giant branch (AGB) wind to a highly aspherical geometry in planetary nebulae (PNe) is puzzling, and binary companions have been suggested to be responsible for this transformation. However, the fraction of known binaries in the evolved stellar phases is very low. The reason is the significant extinction due to the large and dense circumstellar material ejected from the AGB stars. It is sought to find signatures of gravitational interaction between the AGB star and its companion (spiral-shell, bipolar structure, and accretion disk). I will show the viability of deriving the binary parameters from circumstellar patterns. With the advent of state-of-art high-resolution high-sensitivity interferometers such as ALMA, JVLA, and SMA, it is timely to obtain the synergy of theoretical and observational progresses in probing the crucial role of the hidden companions in the late stellar evolution.