Multiple Spiral Branches on Late AGB Stars (Abstract)

Volume 39 number 1 (2011)

Qian Wang

Department of Physics and Astronomy, Iowa State University, Ames, IA 50011; wqinisu@iastate.edu; lwillson@iastate.edu

Lee Anne Willson

Department of Physics and Astronomy, Iowa State University, Ames, IA 50011; wqinisu@iastate.edu; lwillson@iastate.edu

Abstract

(Abstract only) We present some 1-D hydrodynamical models that are capable of generating ring structures around evolved stars. In these models, the pulsation of the star initiates the flow and generates shock waves from a static atmosphere. A secondary period is introduced by an orbiting companion. It creates a series of shocks with different strength. The most energetic one collects all the weak shocks, forming super shocks around the star. The most interesting results are period coupling between pulsation period and orbiting period and multiple spiral arms in the far zone (>100AU). In the near zone (~100AU), the strong shocks greatly alter the density and temperature structure. This study enriches the possible mechanisms for the morphology of proto-planetary nebulae.