Invited Presentation

Circumstellar Patterns of Old Stars: the Messages from Binary Stars via ALMA

Author(s):

Presenter: Hyosun Kim (ASIAA)

A growing consensus has been developing in the past few decades that binarity is key in providing an understanding of the morphological diversities of the circumstellar envelopes (CSEs) surroudning stars in the Asymptotic Giant Branch (AGB) to Planetary Nebula (PN) phase. However, the number of detected binaries in particular with their orbital properties derived are still small. As a consequence, the possible roles of binaries in the shaping of PN and in the CSEs of AGB stars have yet to be clarified. ALMA, simultaneously providing both high sensitivity and high angular resolution, can finally prove the existence of the companion stars to the evolved stars and assess their important roles in late stellar evolution. I will review the recent theoretical and observational investigations on the circumstellar spiral-shell patterns and discuss their implications in linking binary properties to the asymmetric ejection events in the post-AGB phase. Detailed spatio-kinematics of such patterns are revealed by recent ALMA observations, which provide a fossil record of stellar orbital motion and the temporal history of mass loss dynamics during the AGB-PN phases.