Measuring the Frequency and Composition of Extrasolar
Minor Planets

 Jay Farihi  	 University of Leicester  

Abstract:
Asteroids are ancient planetesimals, the building blocks of
terrestrial planets. In the Solar System, we indirectly measure the
composition of asteroids by studying meteorites. Evidence is now
strong that warm dust disks resulting from the tidal disruption of
minor planets exist at between 1% and 3% of all white dwarfs with
cooling ages less than around 0.5 Gyr, providing a ready explanation
for their externally-polluted, metal-enriched atmospheres. These
discoveries provide information that at present can be acquired no
other way: the frequency and bulk chemical composition of minor planet
systems around other stars. I will present work to date using this
novel approach to the spectroscopic study of extrasolar, terrestrial
planetary debris. Currently, there appear to be at least very basic
similarities between the composition of Solar System asteroids and
extrasolar asteroids. For heavily polluted stars, we anticipate that,
eventually, a combination of optical and ultraviolet spectroscopy will
enable the measurement of the relative abundances of two dozen or more
heavy elements representing the bulk chemical composition of
extrasolar minor planets.