Jueves 11 de Abril de 2002, Ip nš 12

Sun ring could point the way to distant planet systems
Por Richard Stenger

Astronomers with the European Space Agency said this month that they had found the first direct evidence of the bright dust ring, located beyond the orbit of Saturn.

Young stars are known to posses thick bands of dust, gas and debris. In the inner regions, planets can coalesce. Farther out, the more thinly distributed material can clump into sparse bands of miniature ice objects.

Any dusty leftovers disappear into deep space. But if an older star such as the sun possesses a dusty ring, some hidden source of material must be sustaining it, the agency's researchers say.

Replenishing the one around the sun requires 50 tons of dust each second, estimated agency scientist Markus Landgraf.

His colleague Malcolm Fridlund elaborated.

"The dust has to come from somewhere," Fridlund said. "The only explanation is that the star has planets, comets, asteroids or other bodies that collide and generate the dust."

The dust ring is fed by the constant collisions of primordial comets in the outer reaches of the solar system, the so-called Kuiper Belt Objects, according to the researchers.

The finding could give a major boost to the search for planets around other stars in the galaxy.

"If we see a similar dust ring around a mature star like the sun, we'll know it must have asteroids or comets," Landgraf said. "If we see gaps in the dust ring, it will probably have planets that are sweeping away the dust as they orbit."

Satellites such as the Cosmic Background Explorer and Ulysses helped astronomers find the disk around the sun. Future planet-seeking missions such as the space agency's Eddington and Darwin may help refine the search around other stars in the coming decades.

Based on data from satellites and observatories, promising places to investigate include the Vega and Epsilon Eridani star systems, researchers say.

  19/02/2002. CNN.