bipolar superbubbles

bipolar superbubbles

by Zequn Li -
Number of replies: 1

Why would a superbubble fueled by the light and breath of OB stars have bipolar structure? I can sort of understand why planetary nebulae exhibit bipolar features, since the orbit spin defines the axis for the poles. Why would a cluster of massive stars do the same?

In reply to Zequn Li

Re: bipolar superbubbles

by David Cohen -

A lot of non-spherical outflows seem to start as spherical outflows, but they're shaped by the density distribution of the material they're expanding into. Specifically, for example, a star with an equatorial disk plus a spherical wind will wind up with a polar wind because the disk will block (or slow) the wind expansion in the equatorial plane and maybe even channel some of it up toward the poles.

On the galactic scale of a MSFR like Carina, the general trend of the interstellar medium's density to be highest in the galactic plane and lower above and below the plane creates a similar situation, where the wind/bubble driven by all the stars (and maybe supernova explosions) combined has its expansion in the galactic plane inhibited. Check this simulation snapshot (and description) out: http://ned.ipac.caltech.edu/level5/Hawthorn/Haw3.html