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Space 'graveyard' reveals bits of an Earth-like planet

Update: October, 11/2013 - 11:45

WASHINGTON – Astronomers have autopsied a distant, broken apart planet and revealed signs of water and a rocky surface together for the first time, delighting scientists on the hunt for alien life.

In a planetary system some 150 light years away, the right conditions for life appear to have once existed, and planets like Earth may have orbited a star known as GD 61, British astronomers reported in the journal Science.

"This planetary graveyard swirling around the embers of its parent star is a rich source of information about its former life," said co-author Boris Gansicke of the Department of Physics at the University of Warwick.

Around 200 million years ago, GD 61 lost its power and began sucking in the nearest planets with its extreme gravitational pull, devouring them to pieces. Now that Sun is what is known as a white dwarf, or a dying star that is circled by planetary debris.

Astronomers have typically studied living stars and the planets that circle them in the search for other worlds that are a reasonable distance from their stars and therefore not too cold or too hot for life.

But a handful of promising far-away discoveries by the NASA Kepler mission have been limited to the size and density of planets in this so-called Goldilocks zone.

Their compositions, whether rocky like Earth or gassy like Jupiter, have remained a mystery because astronomers couldn't get close enough to peer at their surfaces, or inside them.

The latest analysis focused on a dead planet that has been broken to bits, allowing scientists to analyse the fragments and actually see inside the contents.

Previous research has examined 12 destroyed exoplanets, or planets outside our solar system, orbiting white dwarves in this way, but never before has the signature of water been found.

Using ultraviolet spectroscopy data, scientists have shown that the fragments contain about 26 per cent water by mass, far greater than the Earth's 0.02 per cent.

The team detected magnesium, silicon, iron and oxygen in the white dwarf's atmosphere, making up the main components of rocks.

The high proportion of oxygen indicates the presence of water. -- AFP

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