A lot of astronomical research is directed towards either determining the distance
to various things or by trying to determine how old they are. Since stars and galaxies
don't come with convenient labels, we have to try various nefarious ways of extracting
this data from what they do give us, namely the amount and energy distribution of the
light they emit.
White dwarfs are particularly useful in this regard. These are the burned out remnants
of stars like the sun. They've burnt all their hydrogen and helium to carbon and oxygen
and are now slowly cooling down, radiating whatever thermal heat is left from their
previous incarnations. By making a stellar model we can try to determine how old each
white dwarf is based on how cool it is.
White dwarfs are very useful for determining the age of old stellar populations because
the oldest populations have had the most time to burn up their stars and form white
dwarfs i.e. white dwarfs are basically the fossil record of star formation. The problem
is, of course, that being old and cool, they're also pretty faint and it takes a lot
of telescope time to find them.
I and colleagues are busy trying to model the evolution of white dwarfs in the
local stellar neighbourhood and nearby stellar associations called globular clusters,
with the aim of trying to determine the ages of the various components of the Galaxy.