White dwarfs as tracers
of stellar, binary, and
planetary evolution
The study of white dwarfs is essential to our understanding of the
evolution of single and binary stars, as well as of planetary
systems. However, because of their intrinsic
faintness, we do not even know all white
dwarfs within the next 20pc.
Using ongoing deep
ultraviolet, optical & infrared
surveys, we will identify many 10000
white dwarfs across the entire sky, observe
them with the largest telescopes and answer the
following questions
What is the
ultimate fate of
planetary systems?
The Solar system today…
The asteroid belt is located
between Mars and Jupiter at
~500 solar radii.
… in ~5 billion years…
The Sun will become a red giant,
evaporating Mercury, Venus, and
probably the Earth. The asteroids and
outer planets survive this phase, but
move further out as the Sun loses
about half of its mass.
… in >5 billion years…
The Sun is now a white dwarf,
roughly the size of the Earth,
with asteroids and the outer
planets orbiting around it. We
currently know about 2 dozen
white dwarfs with circumstellar
debris of an evolved planetary
system, and we can measure the
chemical composition of exoterrestrial material from highresolution spectroscopy of these
systems.
What are the progenitors of
type Ia supernovae?
Type Ia supernovae are the cosmic beacons that are used to study
the nature of dark energy – yet, we do not know their progenitors.
Using more than 100 orbits Hubble Space Telescope ultraviolet
spectroscopy, we will investigate to what extent white dwarfs
accreting from a nearby companion grow in mass.
White dwarfs:
structure, evolution,
and star formation history
The rarest white dwarfs often provide the most crucial information. Just to name two
examples: we will study ONe white dwarfs that were made by some of the most massive stars
that just about failed to core-collapse into a neutron star, and we will search for the coolest
white dwarfs, that form a fossil imprint of the local star formation history.