Domingo 28 de Abril de 2002, Ip nš 13

Forming planets caught in the act
Por Richard Stenger

A close-up view of a neighboring star system reveals what scientists suspect are planets in the process of forming, offering a glimpse into what our solar system might have looked like billions of years ago.

Astronomers speculate that the Earth and its siblings originated in a dust ring around the sun, much like the one enshrouding the young star Beta Pictoris.

The observations provide some of the strongest evidence that planets form in such stellar dust disks, according to two independent teams of astronomers that announced the discovery this week.

The Beta Pictoris data show multiple warps in the stellar disk, which likely indicates the presence of one or more planets, according to the scientists.

"We've seen disk features before that could be due to planets. To date, however, most of these were discovered far outside the region [analogous to] where planets reside in our own solar system," astronomer David Koerner said in a statement. "And plausible nonplanetary explanations have been found for some of them."

The distortions in the dust ring around Beta Pictoris, however, occur much closer in, at distances comparable to the giant gas planets in our solar system.

Additionally, the warps suggest protoplanets orbiting the parent star at different inclines, much like planets do in our solar system.

For example, Pluto goes around the sun at an incline of 17 degrees compared with the orbiting path of Earth.

Alycia Weinberg, a member of the second scientific group, determined that warped areas of the disk contained smaller, hotter particles.

"It maybe that as a planet warps the disk, it also causes more collision of rocks in the neighborhood," she said.

Beta Pictoris resides 63 light-years away in the constellation Pictor and is about 20 million years old. In contrast, our middle-aged sun is about 4.5 billion years old.


  16/04/2002. CNN.