Friday, September 9, 2011

APOD 1.2

SDSS J102915+172927: A Star That Should Not Exist
     This Milky Way star has fewer metals in it than any other star known to man.  Population I stars have elements heavier than hydrogen and helium and are rich in metals, Population II stars have some elements heavier than hydrogen and helium but are less rich in metal, and Population III stars are composed largely of primordial gas. SDSS J102915+172927 is strange because it is a low mass star and it has fifty times less lithium than came out of the Big Bang. Also, according to ESO this star is composed entirely of hydrogen and helium with only trace amounts of other elements.  According to the study of star formation, SDSS J102915+172927 should not even exist although it is believed to be about 13 billion years old. Astronomers are continually testing different theories of how this could have happened, but there is one leading hypothesis that the fragile lithium was destroyed in the star's core.

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