Scientists Find Bizarre Distant Worlds

S A N   D I E G O, Jan. 10 -- Two “clearly bizarre” planetary systems foundin the orbits of distant stars are puzzling astronomers and raisingnew questions about how planets form.

Planet hunters at the University of California, Berkeley, reported Tuesday that a star 123 light years away is being circledby two objects, one of which may be the biggest planet ever foundoutside the solar system. Around another star, the astronomersfound two planets moving in lockstep, gravitational harmony.

The astronomers announced their discoveries at the nationalmeeting of the American Astronomical Society.

Profound Theoretical Implications

Geoffrey Marcy, leader of the planet-searching team, said a starcalled HD168443 is being circled by a planet about 17 times moremassive than Jupiter. It is by far the largest planetary-likeobject yet found beyond the solar system.

“This is more massive than a planet and it defies theconventional definition for a planet,” said Marcy.

The object is big enough to be called a brown dwarf, which issometimes called a “failed star.” Brown dwarfs are usuallydefined as stellar objects that did not collect enough mass toignite the nuclear fires that causes a star to shine. Generally, anobject must acquire a mass greater than 13 times that of Jupiter,the largest planet in the solar system, to start the fires burning.Yet, the object orbiting HD168443 is larger.

“We have never seen anything like this,” said Paul Butler, aCarnegie Institution of Washington astronomer who is a member ofthe planet-hunting team. “To call it a brown dwarf sweeps themystery under the rug. It is a mystery system.”

“This defies explanation,” said Marcy. “We don’t know if itis a brown dwarf or some type of hybrid.”

The team has discovered more than 30 planets outside the solarsystem. Other teams have found about 20 additional ones. Most suchplanets are two to three times more massive than Jupiter. NoEarth-sized planets have been found.