'Rebel' planet found outside solar system

17 Jun 2002

A new planet that breaks all the rules about how and where planets form has been identified in orbit of the twin star 16 Cygnus about 70 light years from Earth in the constellation commonly known as the Northern Cross. The Jovian-sized planet has a roller-coaster like orbit that swoops down close to its central star and then swings far out into frigid fringes, following a strange egg-shaped orbit that is unlike that of any other known planet.

"Of all the stars you might see in the sky, Cygni B is the most similar to our sun," said William D. Cochran, head of University of Texas team that discovered the planet. A group at San Francisco State made the discovery independently at roughly the same time. Cochran reported the star has the same mass and temperature as the sun, but the nearby twin star of Cygni B creates an entirely different type of environment.

Every 250,000 years, Cygni A and B pass within 65 billion miles of each other, a grazing passage by stellar standards. Cochran said the stars are so close, that the gravitational tug of Cygni A may have pulled the new planet into its wildly eccentric orbit. During one part of its 804-day-long year, the planet would pass within 67 million miles of its sun. This would be the planet's summer, said Cochran. Then the planet would swing far out, reaching a point 158 million miles from the star. This would be its winter and it would last more than 500 days, the researcher said.

The new planet is the latest in a series of bodies found in orbit of stars outside the solar system and is part of a quickening effort by astronomers to find distant worlds. By some estimates, as many as 11 of these objects have been discovered so far.