Thursday, August 25, 2011

A (galactically) nearby supernova

Phil Plait reports that there's a new supernova in the galaxy M101, one of the nearest galaxies. It's only magnitude 17.2 right now, not visible without a 15+ inch telescope, but it's supposed to brighten to magnitude 11 - enough that I may be able to spot it with my 8-inch scope.

This is a pretty major event; there's only been one supernova in recent years (in 1987) that was closer. It's a Type Ia supernova, which unlike many supernovae is not formed by the collapse of a supermassive star. Instead, it is created by a binary star system, consisting of a large, cool, and massive red giant and a small, hot white dwarf. The white dwarf steals material from the red giant; when it reaches 1.38 times the mass of the sun - the Chandrasekhar limit - it can no longer support itself, and it begins to implode. Carbon, normally not prone to nuclear fusion, fuses into magnesium in what is called carbon detonation, and the thermonuclear 'flame' destroys the star in a burst of energy equal to two billion billion billion billion billion of the bombs that destroyed Hiroshima.

Discovery notice
Archival discovery of possible precursor stars

2 comments:

DTH Rocket said...

That is pretty cool. What is the statistic? 4 supernovae every 1000 years in the Milky Way Galaxy?

The EGE said...

Wikipedia says every 50 years in the Milky Way, though most are hidden by galactic-plane dust. Last one we saw was 1604.