Shocks, clumps and tails

The third of the DCU astrophysics colloquia takes place on Thursday, 12 April, at 15.00. Title: Shocks, clumps and tails. Speaker: Professor John Dyson, University of Leeds,
Location: S209, Research & Engineering Building'
Professor Dyson is Editor-in-Chief of Astrophysics and Space Science, an international journal. He has written two editions of a widely used textbook and edited several books on specialist subjects. Tea & coffee will follow the talk and all are welcome to attend.
Abstract: "Many, if not all, diffuse astrophysical sources consist of extended flows interacting with highly inhomogeneous surroundings. Examples include planetary and Wolf-Rayet nebulae, starburst superwinds and supernova remnants. Embedded clumps act as mass sources for the flows. This mass loading is important for a variety of reasons. For example the global flow properties are profoundly affected by the mass addition. Again the global shocks generated in interactions with homogeneous surroundings may be modified when clumps are present and a system of local shocks can be set up. The material injected from clumps couples to the flows in ways that depend on the morphology of structures intermediate between very small scales (e.g. boundary layers) and the scale of the global flow itself. These intermediate scale structures are extended and are often visible as tails. I will discuss calculations of structures produced when bubbles interact with clumpy surrounds and describe in detail some recent work on the tails of the planetary nebula NGC 7293 (the Helix Nebula)."
Contact: Dr Turlough Downes, School of Mathematical Sciences, Dublin City University,
Glasnevin, Dublin 9. Tel: +353-1-700 5270, FAX: +353-1-700 5786, http://www.dcu.ie/~downest/