Merging White Dwarfs Create Helium Stars

[Dragon Star]

http://www.universetoday.com/am/publ...ns.html?932006

An international group of astronomers has used the Hubble Space Telescope to determine the origin of an unusual class of objects called extreme helium stars. These objects are formed when two white dwarf stars merge together. Since they were first discovered more than 60 years ago, less than two dozen have found. They contain almost no hydrogen, and are dominated by helium and other heavier elements. When two white dwarf stars merge together, the resulting star swells up to become a super-giant star rich in helium.

lol, I didn't even know of any cases where we were aware of stars that have merged, very interesting article.

[sunofsky]

infact this is a great information about the white dwarfs mergings, it is pretty difficult for me to explain, but you know in the astronomy the logic also can be develop to say the facts or the possibilities as well, it is throughly acceptable some, many time it get some oppose, but gradually it is seen that the logic in astronomy become a need in explaining the facts.
we have to take the support of logic.

sunil ( you may be agree or may be not)

Class F stars have been leaving main sequence for almost ten billion years (G for several billion years/ I think some class A stars became white dwarfs eleven billion years ago) so there could be a trillion white dwarfs in our galaxy = more than the number of main sequence stars in our galaxy. Almost as many white dwarfs as main sequence is more likely. When they are close binaries (could we tell a very close binary is not an extreme helium star?) merging is not improbable. Neil