15.45-16.30u Jasper Lukkezen & Louk Rademaker 
(begeleiders: Vincent Icke & Vivi Rottschäfer)
"Shock waves through inhomogeneous media"

Planetary nebulae (PN) have often weird shapes, due to an inhomogeneous
interstellar medium. We investigated the propagation of the shock wave
that forms a PN. The form of the shock wave depends on the initial
density distribution. The equation that described the shock propagation
is a first order non-linear partial dierential equation. We solved the
equation analytically for some basic functions and made estimations for
more complex density functions. We also made a model that used toroidal
coordinates and one in three dimensions. The toroidal model resembles
the Red Rectangle nebula.
We also inverted the two-dimensional equation to derive the initial
density function from a known shock wave. We used an numerical model to
compute the density prole for twelve known planetary nebula. That lead
to a qualitative classication into the ellipsoidal, two-stream and and
irregular nebula. Inserting some test shock waves into this equation
shows the existence of a extraordinary 'bump' in the density function.