Anomalous White Dwarfs: Largest Collection Of White Dwarfs Made Of
Helium Discovered
http://www.sciencedaily.com/releases...0423100808.htm

"Twenty-four unusual stars, 18 of them newly discovered, have been
observed in new Hubble telescope images. The stars are white dwarfs, a
common type of dead star, but they are odd because they are made of
helium rather than the usual carbon and oxygen. This is the first
extensive sequence of helium-core white dwarfs to be observed in a
globular cluster, a dense swarm of some of the oldest stars in our galaxy."

"Being coupled with companions also helps explain the stars' atypical
chemical make up. White dwarfs are stars that have reached the end of
their lives and have run out of fuel. Most stars burn their fuel leaving
behind a dense ball of carbon and oxygen, but these white dwarfs are
made of helium. Cool suggests that a star that goes on to become a
helium-core white dwarf must have a close companion so that when the
star became a red giant and expanded, its outer layers spilled onto the
companion. The star never had the chance to reach maturity and burn its
helium into carbon and oxygen."