posted May 28, 2004 10:12 AM              

Possible Baby Planet Spotted by Spitzer Telescope

Thu May 27, 5:10 PM ET
By Deborah Zabarenko

WASHINGTON (Reuters) - The youngest planet ever detected -- a baby less than 1 million years old -- may have been discovered by NASA (news - web sites)'s Spitzer Space Telescope, scientists reported on Thursday.

The possible infant planet was spotted circling a star known as CoKu Tau 4, some 420 light-years away in the constellation Taurus, according to astronomer Dan Watson of the University of Rochester, New York.

A light-year is about 6 trillion miles, the distance light travels in a year.

Researchers have identified more than 100 so-called extrasolar planets -- those found outside our solar system -- but generally these objects were thought to be a billion years old or more. Earth and its immediate planetary neighbors are all about 4.5 billion years old, well into middle age.

This possible planet was detected by examining the dusty disk around the star CoKu Tau 4, where scientists found a donut-like hole in the dust. The putative planet may have formed by scooping together this dust, scientists said at a briefing at NASA headquarters.

"The object is only a million years old," Watson said. "That probably makes it the youngest planet that we've ever seen, and young enough that it really causes problems for the major theories of planetary formation."

One theory of planetary formation holds that planets form when small objects called planetessimals slam together and stick, gradually building up a planetary mass. A planet made by quickly collecting itself from the planetary dust around a star is a different way of looking at the problem, and would allow for planets to form much earlier in the process.

The discovery of the possible infant planet was one of three findings by the Spitzer spacecraft, which looks at the universe through infrared light as it trails Earth in its journey around the Sun.

Spitzer also found significant amounts of icy organic material in the dusty disks surrounding other infant stars, which could give a clue to the origins of icy bodies like comets, often described as dusty snowballs in space.

This finding is significant because some astronomers believe comets may have brought water to Earth, along with life-enabling materials. These kinds of materials have been detected in space but this is the first time they have been clearly detected in the dust of planet-forming disks.

Spitzer also uncovered more than 300 newborn stars in a stellar nursery called RCW 49, about 13,700 light-years from Earth in the constellation Centaurus.

posted May 28, 2004 12:49 PM              

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