FOR the first time, astronomers have detected a belt of asteroids in another
solar system. The alien belt may contain 200 times as much mass as our own Solar
System鈥檚 asteroid belt.
The asteroids circle a luminous young star known as Zeta Leporis some 60
light years from Earth in a constellation known as the Hare. Christine Chen and
Michael Jura of the University of California in Los Angeles used the 10-metre
Keck telescope at Mauna Kea, Hawaii, to detect the feeble infrared radiation
emitted by microscopic dust particles lying in a band that spreads from 375 to
915 million kilometres from Zeta Leporis.
Chen believes their observations could shed light on what happens in other
solar systems. 鈥淲e hope to learn more about the region where Earth-like planets
may be forming,鈥� she says.
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Dust belts around stars have been found before, but never so close in. Left
on their own, the dust particles would spiral into the star within 20,000 years
or so. Apparently, the dust around Zeta Leporis is being replenished
continuously, most probably by collisions between larger rocky objects. The same
process takes place in our own asteroid belt.
Jura believes it鈥檚 impossible to say whether there are also Earth-like
planets in orbit around Zeta Leporis. But according to Mark Sykes of the
University of Arizona鈥檚 Steward Observatory, the new find suggests that there
should be a Jupiter-like giant planet further out. He says something must have
鈥減umped up鈥� the circular orbits of the asteroids, so they ended up in
criss-crossing elliptical orbits where they would collide and generate debris.
鈥淚t鈥檚 a fascinating result,鈥� says Sykes.