How do supernovae arise? And when they become white dwarfs, what effects will they create in the world? And what effect do they have on the expansion of the world?
Most supernovae begin as stars whose cores collapse, but a supernova, in the simplest model, begins as a white dwarf star that borrows mass from a companion star. When it reaches critical mass, it erupts in a titanic thermonuclear explosion. Although they are not identical, they are more luminous than any other type of supernova. At the same time, their redshift is a direct indication of the expansion of the universe since the supernova explosion.
Measuring the expansion history ultimately depends on comparing the distance and redshift for a sufficient number of Type Ia over a long period of time. This is how accelerated expansion, driven by dark energy, was independently discovered by two competing teams and announced in 1998. For this discovery, in 2011, Saul Perlmutter shared the Nobel Prize in Physics with Brian Schmidt and Adam Reiss of the rival supernova High-z.
The new Rubin supernova announced at the AAS meeting was first observed in a supernova survey conducted by the Supernova Cosmology Project using the Hubble Space Telescope (HST) in 2004.