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Old October 19th 17, 01:45 PM posted to sci.astro.amateur
Martin Brown[_3_]
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Posts: 189
Default Supernova structure

On 17/10/2017 07:56, Gerald Kelleher wrote:
https://www.scientificamerican.com/s...E81BC8B34C6357

Stellar evolution has a specific geometry to it whether as the
antecedent supernova star or after the event occurred -

https://apod.nasa.gov/apod/image/0701/sn1987a_hst.jpg


That much is true. To a very good approximation stars are spherical with
a small equatorial bulge determined by their rotation period. The
shorter their rotation period the more oblate they are.

Jupiter with an 8 hour period is obviously oblate whereas the sun with a
~23 day period is almost perfectly spherical.

When stars evolve to their giant phase the effective surface gravity at
their equator means that the outward solar wind is strongest in the
equatorial plane. Planetary nebulae like M57 and (misleadingly named
for how they looked a bit like planetary disks in early telescopes) are
examples of stars shedding their outer atmosphere in later life.

How they appear to us on Earth depends on the angle between our line of
sight and their spin axis. A zoo of famous ones online at:

https://en.wikipedia.org/wiki/List_of_planetary_nebulae

--
Regards,
Martin Brown