Dead Star Offers Clues to the End of Our Solar System

CHICAGO (AFP) - "British astrophysicists said they have found evidence of planetary material in the orbit of a white dwarf for the first time, a discovery that may provide clues to the end of our own solar system billions of years from now.

The team at Britain's Warwick University identified an unusual ring of metal-rich gas orbiting very close around a white dwarf, a former star, about 463 light years from our solar system in the constellation Virgo.

Their analysis of the traces of magnesium, iron and calcium seen in the ring suggests the materials are the evaporated remains of an asteroid about 50 kilometers (31 miles) in size, which got sucked into the orbit of the white dwarf and then gradually pulverized and irradiated.

"This is very direct evidence that white dwarfs have planetary systems around them," said Tom Marsh, professor of experimental physics at Warwick University.

A white dwarf begins as a star similar to our sun. Late in life, the star swells into a red giant probably destroying any inner planets at orbits such as those of Mercury and Venus, and pushing out other planets and asteroids to a more distant orbit than before.

The star that mutated into this particular white dwarf, which has been dubbed SDSS 1228+1040, would have destroyed all planetary material out to a distance of 500 million miles.
But asteroids still exist today at larger distances from this white dwarf.

If as the astrophysicists suspect, this star was part of a planetary system with an asteroid belt, then it could serve as a model for what will happen to our own solar system in five to eight billion years when the sun becomes a white dwarf.

The suggestion is that our planets could collapse in this way in the distant future. "It's like a glimpse into the future of our solar system," said Marsh.

The presence of the ring helps solve a problem for astronomers who, up till now, have been puzzled by the apparent absence of planets around white dwarfs. But it also points up just how unusual our solar system is. The Warwick University team studied data on 500 additional white dwarves without finding conclusive evidence for another system harbouring such a ring around it.

The rarity of such a ring made from a disrupted asteroid tells us that the majority of planetary systems may look quite different from our own solar system," the researchers wrote. "They may not have asteroid belts at all, or not as far out as it is the case in the solar system, or they may not have planets at such great distances as Mars or Jupiter."

The study is published in the journal Science."

Well... this is definitely food for thought...