Further odd evidence making us re-examine the Universe

[jmercer]

First it was Dark Matter, Dark Energy and the ever-increasing speed at which the Universe is expanding...

Then it was a question about the proper value of the infamous cosmological constant; suggesting that the age of the universe may be greater than currently believed...

Now it's this (http://www.space.com/scienceastronomy/060920_supernova_atypical.html).

I love science - the only self-correcting human-driven system I know of. :)

[HappyCat]

Well, the American political system is supposed to be self correcting, but the success of that is up for debate ;)

Does anyone know how we arrived at the conclusion that a Type 1a supernova could be used as a standard candle? I have sometimes wondered this, and I guess this is a good place to ask.

[GodMark2]

Does anyone know how we arrived at the conclusion that a Type 1a supernova could be used as a standard candle? I have sometimes wondered this, and I guess this is a good place to ask.

To answer this, we need a bit more info about what a Type1A supernova is.

A Type1A supernova is the explosion of a white dwarf. The only way to create a white dwarf that we know of is to have another nova. If the star forming that first explosion is too small, we get something smaller and lighter such as a brown dwarf. If it is too big, we end up with either a neutron star of a black hole.

Because of this, white dwarves have a very narrow range of allowable masses. This means that their explosions have a narrow range of allowable energies.

The current issue of Scientific American has an article (http://www.sciam.com/article.cfm?chanID=sa006&colID=1&articleID=000160CC-A71B-150E-A26183414B7F0000) that goes into more depth on this.