Blowing up warped disks

Stars do not go gently: even low-mass stars such as our Sun blow up in the end, seeding space with the elements of which we are made. Usually, the resulting nebulae show a pronounced bipolar or even multipolar shape. Balickʹs "generalized interacting-winds" model posits that this is due to an interaction between a very fast tenuous outflow, and a disk-shaped denser atmosphere left over from an earlier slow phase of mass loss. Analytical and numerical work shows that this mechanism can explain cylindrically symmetric nebulae. However, many circumstellar nebulae have a "multipolar" or "point-symmetric" shape. I demonstrate that these seemingly enigmatic forms can be easily reproduced by a two-wind model in which the confining disk is warped, as is expected to occur in irradiated disks. Large-scale explosions in other non-planar disks, such as might occur in active galaxies, are expected to show similar patterns.