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Scientists find evidence of complete solar system

By William Schiffmann, Associated Press, 04/15/99

SAN FRANCISCO - The first evidence of the existence of another solar system somewhat like our own was reported today.

The discovery indicates that the Milky Way, which contains about 200 billion stars, probably has numerous planetary systems, San Francisco State University researchers said in announcing the find.

Astronomers knew one planet was circulating around Upsilon Andromedae, 44 light years from Earth. But after of studying 107 stars for 11 years at the Lick Observatory near San Jose, scientists said evidence of two additional planets has been spotted. The discovery would mean that for the first time, a true solar system -- with multiple planets -- had been located.

"It implies that planets can form more easily than we ever imagined, and that our Milky Way is teeming with planetary systems,'' said Debra Fischer, one of the researchers.

The planets were discovered using a method that measures their gravitational pull on their star, not by direct observation. Planets' gravity tugs on their stars, causing them to wobble slightly. By examining the star's ultraviolet light transmissions, astronomers can calculate back-and-forth shifts in the ultraviolet wavelengths. A larger wobble indicates the orbiting planet is large.

Astronomers from the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., and at the High-Altitude Observatory in Boulder, Colo., independently identified the two new planets.

The innermost of the three planets has at least 75 percent of the mass of Jupiter and is very close to its sun, orbiting once every 4.6 days. The middle planet is twice Jupiter's mass and orbits the star every 242 days from a location about as far as Venus from the sun. The outer planet has the mass of four Jupiters and orbits its star every 3 to 4 years. It is more than twice as far from its star as Earth is from the sun.

No theory predicted that so many huge planets would form around a star, said astronomer Geoffrey Marcy, a member of the discovery team.

"I am mystified at how such a system of Jupiter-like planets might have been created,'' he said. "This will shake up the theory of planet formation.''

Alex Wolszczan, an astronomy professor at Penn State University, called the discovery an "important step'' toward understanding the cosmos.

"It has been anticipated and awaited by the scientific community. It's nice to see it's finally happened,'' he said. "What I get right away from this particular discovery is that it emphasizes even more how different those systems are from our own.''