München 2019 – wissenschaftliches Programm
EP 11.3: Vortrag
Freitag, 22. März 2019, 13:00–13:15, HS 19
Flow patterns and spiral ring structures in the environment of massive stars — •Dieter Nickeler and Michaela Kraus — Astronomical Institute AVCR, Ondrejov, Czech Republic
Observations with modern facilities reveal the presence of structured environments around evolved massive stars (spiral arms, rings, arcs etc.). The dynamics of gas around stars is often modelled by hydrodynamics (HD). Accretion and decretion phenomena, i.e. outflows from stars, are connected with nonlinear flows, today often treated with numerical methods. The classical representation of nonlinear flows has been done already by Euler, Lagrange and Stokes, later by Clebsch and Monge, using vector potentials from which the flow fields can be derived. These potentials, applied to the HD equations, lead to nonlinear Poisson equations, and represent the vortices or the compressibility of the gas. These nonlinear Poisson equations represent an analogy to nonlinear Schroedinger-Eigenvalue or nonlinear diffusion equations, or the equations of nonlinear magnetohydrostatics. Our aim is to extend these equations and involved methods as tools for investigating the circulation and outflow of circumstellar matter around (massive) stars. Preliminary results, as the existence of blow-up solutions and other nonlinear instabilities, are discussed.