Hydrodynamics of circumstellar nebulae in 3D

Abstract

During their evolution massive stars lose a large fraction of their initial mass in the form a stellar wind. This strong outflow shapes the surrounding gas through supersonic collisions. As the star evolves the wind parameters change, leading to the formation of complex circumstellar structures: the circu mstellar nebulae. These nebulae reflect the evolution of the stellar wind and therefore the evolution of the progenitor star itself. We intend to make 3D h ydrodynamical models of these nebulae in order to compare them to existing observations. So far models of circumstellar nebulae have been calculated mainly in 1D and 2D due to the limitations of the available computational resources. However, even 2D models show complicated structures formed by local instabil ities. Only by simulating the interactions in three dimensions can we hope to create fully accurate models. These models can then be used, not only for dir ect comparison with observations, but also as input for studies of those phenomena that take place inside the circumstellar medium such as supernovae and g amma-ray bursts.