In article ,
Jos Bergervoet writes:
If they oscillate up and down the plane, then each time they go through
the plane and traverse the denser regions, the elastic collisions with
other stars create friction, just like atoms in a gas see friction by
the collisions with other atoms (or molecules).

This called "dynamical friction." (I expect Jos knows that, but some
readers may not.) The question is how long it takes for this process
to damp out the vertical motion. If not very long, why do the thick
disk and halo stars still have the orbits they do?

This does not seem to be different from what happens before they go
supernova, of course..

The progenitors of core-collapse SNe are massive, therefore young,
stars and therefore presumably belong to the thin disk population.

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