White dwarfs gobble Earthlike treats

Rocky planetary crumbs found in the dead stars' atmospheres

10:07am, August 15, 2011

Astronomers studying the atmospheres of planet-munching white dwarf stars have found that some stellar meals included the same ingredients as Earth.

Remains of rocky bodies that once circled the white dwarfs pepper the gas envelopes around the dead stars. The ratios of elements in these remains — called “pollution,” since it mars the star’s normally pristine hydrogen or helium atmosphere — tell astronomers what the bodies were made of and where they might have come from. Although about as common as normal stars in the Milky Way, white dwarfs aren’t the most obvious choice for astronomers looking for traces of extrasolar planets — but, it turns out, the dense, collapsed stars may be incredibly useful.

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