Distance to galaxies using the standard candle method, and supernovaes ?

Question

Does anyone know which type of supernovae would be the best to use (using the standard candle method) to find the distance to another galaxy, and why supernovae's of this type might plausibly have similar maximum luminosities ?

Thanks for any help.

Answer 1

Type 1A supernovae are the best for this purpose because they are "standard bombs" that almost always have about the same maximum luminosity. That is because white dwarfs destabilize and blow themselves apart when their mass exceeds 1.44 times that of the Sun. Mutual repulsion between electrons can no longer support the star at that point, and the star collapses. Most white dwarfs are made of carbon and oxygen, which can fuse explosively under the right conditions.  Before it could become a neutron star, runaway carbon and oxygen fusion starts in the core and like a firestorm consumes the whole star from the inside out, detonating it like a thermonuclear bomb. Since all white dwarfs have the same mass limit, they release the roughly the same amount of energy when they destroy themselves. They also create the same amount of radioactive cobalt and nickel whose decay keeps the expanding fireball very hot for a long time, the runaway chain reaction that blows apart a white dwarf lasts less than a second. These are the most numerous supernovae since most stars die as white dwarfs and most stars are also members of double or multiple star systems. If a white dwarf absorbs enough matter from a companion star, it will inevitably explode as a supernova, leaving nothing but a cloud of rapidly expanding debris and a shrunken star behind. The only way a Type 1A supernova can be brighter is the merger and explosion of two white dwarfs that were once a double star system. Such supernovae have apparently been seen already.