[ExI] The closest Supernova candidate

[John Clark]

Actually the closest Supernova candidate is not Betelgeuse but IK Pegasi B,
it's only 154 light years away versus 650 light years for Betelgeuse,
that's still probably distant enough to be safe but its getting a little
dicey.  IK Pegasi B is far too dim to be seen by the naked eye but it's in
orbit around IK Pegasi A  which can be seen because it's about twice as
massive as the sun and 8 times brighter.  IK Pegasi B is dim because it's a
White Dwarf, a star about the size of the Earth but more massive than the
sun.  IK Pegasi B is composed almost entirely of Carbon and Oxygen and is
very hot and very dense, but it's not hot or dense enough to fuse the
Carbon and Oxygen. However IK Pegasi B is already very close to the
Chandrasekhar
limit of 1.44 solar masses, and because it is in such a tight orbit around
its much larger companion star (less than the orbit of Mercury)  IK Pegasi
B is constantly gaining mass by gravitationally pulling matter off of IK
Pegasi A.

When it reaches 1.44 solar masses it will no longer be able to support its
own weight and will collapse in on itself, the resulting compression will
increase the temperature and density until, almost instantly all the Carbon
and Oxygen, virtually the entire star, will undergo thermonuclear fusion,
And then everything will blow sky high in a Type 1a Supernova (someday
Betelgeuse will be a Type 2 Supernova).

 John K Clark
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