Terrestrial planet(esimal) composition from white dwarf stars

Rocky Extrasolar Planetary Compositions Derived from Externally-Polluted White Dwarfs

Study of PG 1225-079 and HS 2253+8023.

Seems that white dwarfs might provide a useful insight into the composition of extrasolar terrestrial planets.

http://www.newscientist.com/article/dn23071-astrophile-zombie-stars-feed-on-earthlike-exoplanets.html

"...Presenting this week at a meeting of the American Astronomical Society in Long Beach, California, Jura showed that oxygen, magnesium, silicon and iron are present in similar proportions to what exists on Earth, collectively making up 85 per cent of the mass of the heavy elements seen in their atmospheres. The team also showed that the stars had, on average, swallowed an amount of matter equal in mass to that of the asteroid belt in our solar system..."