A white dwarf is a type of star that contains about as much matter as
the Sun (nearly a million times as much as the Earth), but packed into a
size no bigger than the Earth. Most of the stars in our galaxy will
eventually become white dwarfs later in their lives - after the hydrogen
fuel burning deep inside runs out. This won't happen to the Sun for another
5 billion years or so.
Some stars have already become white dwarfs, and astronomers can see them
as tiny points of light in the sky, visible only through large telescopes.
As it turns out, some of the white dwarfs show very regular variations in
the amount of light reaching our telescopes. The pattern of this variation
suggests that these white dwarfs are pulsating - as if there are continuous
star-quakes going on. By studying the patterns of
light variation,
astronomers can learn about the interior structure of white dwarfs - in
much the same way as seismologists can learn about the inside of the Earth
by studying earthquakes. For this reason, the study of these pulsating white
dwarfs is called
asteroseismology.
The observations of pulsating white dwarfs are being done with the
Whole Earth
Telescope - a collaboration of astronomers around the world. I am
involved in helping to make these observations, but I also work on
interpreting them using our mathematical models. I approach the models in
two ways:
- I assume the models are accurate representations of the real white
dwarf stars, and I try to find the combination of
model parameters that do the best job of matching the observations.
- I assume the models are flawed representations of the real white
dwarf stars, and I try to find what changes to the physical laws governing
the structure of the stars are possible without ruining the ability of
the model to match the observations.
