A Strange Supernova is worrying cosmologists

24 September 2006
Posted by Chris Smith.

A supernova is basically an exploding star, the explosion can be cause for a variety of reasons. A very important type is 1a, this is caused where an old star ember called a white dwarf is slowlyy aquiring matter from another star (probably a red giant), eventually it gets so heavy that it can't support itself and it collapses. In this collapse carbon and oxygen start to fuse together creating heavier elements ( almost all the heavy elements in the universe were made in supernovae), this releases an immense amount of energy and blows the star apart creating an explosion 5 billion times brighter than the sun.  Because the point at which the white dwarf collapses should always be about the same, the explosion should always have about the same amount of fuel so it should be the same brightness.

  This makes typoe 1a supernovae increadibly useful as a way of judging distance because the further away something is the dimmer it appears, so if you know the brightness you can work out the distance. Cosmologists have used this to work out how far objects are, and with the red-shift which tells them how fast they are moving they have deduced all sorts of things about dark energy and the shape of the universe.

  Unfortunately Andrew Howell has found what appears to be a type 1a supernova that is 2.2times brighter than the model says it should be possible to be. Maybe the star was spinning fast which allowed more matter to build up before it collapsed. This could mean that astonomer's have observed lots of supernovae that are actually at lot further away than was calculated and cosmolgists are going to have to look at their data, and possibly their conclusions very carefully.

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