Nearing the end. The star CW Leonis has swollen to engulf any nearby planets and is vaporizing a belt of comets.

Wet Solar System Found

Dick writes about Earth and planetary science for Science magazine.

WASHINGTON, D.C.--A solar system is dying, and in its last gasps astronomers 5 light-years away can see signs that a billion comets are blazing into oblivion at once. The discovery of huge amounts of water streaming away from an aging, swollen red giant star in the constellation Leo shows for the first time that our own planetary system is not alone in harboring a key ingredient of life as we know it, researchers told a press conference at NASA headquarters today.

Scientists operating the Submillimeter Wave Astronomy Satellite (SWAS) in low-Earth orbit had no intention of getting into astrobiology. SWAS was designed to measure water, oxygen, and carbon in gas clouds around the galaxy, but a gap in the observing schedule seemed best filled by a star called CW Leonis, one that should have had practically no detectable water anywhere near it. Instead, SWAS detected 10,000 times more water than the star could have been giving off. The only way to make that much water is by vaporizing it from a billion icy comets at once, SWAS researchers concluded. "Nothing but comets comes close to the amount of water SWAS is seeing," says SWAS team member David Neufeld of Johns Hopkins University. "We believe we are witnessing the apocalypse that will engulf our solar system in 6 billion years."

CW Leonis, it appears, is consuming a belt of small icy bodies orbiting it just as Kuiper Belt objects (KBOs) orbit our sun beyond Pluto and Neptune. KBOs become active comets only when they swoop near the sun, but CW Leonis, running low on nuclear fuel, has ballooned out to the distance of Jupiter from our sun and blazed to 5000 times its normal luminosity. That would vaporize the ice of bodies orbiting 10 to 100 times the Earth-sun distance from CW Leonis, SWAS researchers report in this week's issue of Nature, turning each into an active comet with a fuzzy glowing head and streaming tail.

"If their interpretation is correct, instead of just finding huge planets around other stars, we're finding comets," says astronomer Tobias Owen of the University of Hawaii, Honolulu. "A lot of us believe these icy bodies are fundamental building blocks of planets. It's nice to know they're out there. It helps the prospects of finding planets, planets with the [gases] that make atmospheres and oceans." And that could sustain life.

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