Berkeley scientist helps locate new Jupiter-like planet

Daily Planet Wire Services
Friday June 14, 2002

A professor from the University of California at Berkeley and a colleague today shared with NASA their discovery of a planetary system that reminds them a little of our own solar system.  

At a news conference at NASA headquarters in Washington, D.C. today, UC Berkeley astronomer Geoffrey Marcy and Carnegie Institution of Washington astronomer Paul Butler announced the discovery of a Jupiter-like planet orbiting a sun-like star at nearly the same distance that Jupiter orbits our sun. 

"This is the first near analog to our Jupiter,'' said Marcy, a professor of astronomy and director of UC Berkeley's Center for Integrative Planetary Science. 

"All other extrasolar planets discovered up to now orbit closer to the parent star, and most of them have elongated, eccentric orbits. This new planet orbits as far from its star as our own Jupiter orbits the sun.'' 

The star is 55 Cancri in the constellation Cancer. It was already known to have one planet, which was also discovered and announced by Marcy and Butler in 1996. That planet is a gas giant slightly smaller than the mass of Jupiter, and whips around the star in 14.6 days at a distance of only one-tenth that from the Earth to the sun. 

While the newly discovered planet is estimated to be between 3.5 and 5 times that of Jupiter, its slightly elongated orbit carries it around the star in about 13 years. Marcy and Butler say that is comparable to Jupiter's 11.86-year orbit. 

"We haven't yet found an exact solar system analog, with a planet in a circular orbit and a mass closer to that of Jupiter,'' Butler noted. 

"But this shows we are getting close, we are at the point of finding planets at distances greater than 4 AU from the host star. And we found this planet among the 107 stars we first targeted when we started looking for planets at Lick Observatory in 1987, so I think we will be finding more of them among the 1,200 stars we are now monitoring.''