Astronomers discover new solar system

CNN, April 15, 1999
Web posted at: 1:45 p.m. EDT (1745 GMT)

WASHINGTON (CNN) -- Astronomers said Thursday they had discovered the first solar system with multiple planets outside our own, with three massive planets orbiting a sun-like star.

All three planets circling the star Upsilon Andromeda are gas giants like Earth's big neighbor Jupiter. However, an Earth-type planet might also be a part of this system, one researcher said.

"Our observations can't rule out Earth-sized planets as well in this planetary system, because their gravity would be too weak for them to be detectable with present instruments," Peter Nisenson of the Harvard-Smithsonian Center for Astrophysics said in a statement.

Astronomically, the system is not far away: 44 light years. Its sun is so near and bright, it can be seen by the naked eye during summer and fall.

Scientists have previously identified at least 18 extrasolar planets, but this was the first time they detected a system comparable to the nine-planet grouping that includes Earth.

"What we have found now, for the first time ever, is indeed a full fledged system of planets around the star Upsilon Andromeda," said Geoffrey Marcy, professor of astronomy and physics San Francisco State University.

animation of inner planet
Animation showing the inner planet that revolves around Upsilon Andromedae every 4.6 days   

The finding suggests that there may be far more planets in our galaxy than previously thought, the researchers said.

"When I look up at the stars now at night I can imagine easily that every one of them has planet around them," says Debra Fischer, a professor of physics and astronomy at San Francisco State University.

Astronomers have searched for planets outside our solar system by focusing on the behavior of certain sun-like stars, such as Upsilon Andromeda.

Stars with a characteristic wobble are believed to have a large planet orbiting around them, with enough gravity to tug on the star.

Astronomers had earlier identified one of the three planets -- the closest one to this star -- but only recently determined that there were two others from their gravitational affect on Upsilon Andromeda.

Can they support life? Scientists don't know, because present technology is not advanced enough to determine what the planets are made of That, Marcy says, is astronomy's next challenge.

San Francisco Bureau Chief Greg Lefevre and Reuters contributed to this report.





Multi-planet System Detected

3 worlds found orbiting star in Milky Way

The Washington Post, April 15, 1999


Elated astronomers yesterday announced the discovery of the first multi-planet system ever found around a normal star other than our sun, moving civilization a step closer to its ancient quest for kindred havens where life might have arisen.

The signal of three orbiting worlds emerged from 11 years of telescope observations of the star Upsilon Andromedae, which is bright enough to see with the naked eye and is located a relatively close 44 light-years (about 264 trillion miles) from Earth in the direction of the constellation Andromeda.

The findings were announced in San Francisco by two independent teams from four institutions who confirmed each other's conclusions using different equipment.

The discovery "implies that planets can form more easily than we ever imagined, and that our Milky Way is teeming with planetary systems," said one of the astronomers, Debra Fischer, of San Francisco State University.

"This is the one we've all been waiting for," said Stephen Maran, a spokesman for the American Astronomical Society. "Astronomers' hearts are in their throats."

The discovery provides the "first clear evidence" that science fiction writers are right to depict their characters hopping from planet to planet throughout the galaxy, "like a bumble-bee going from daisy to daisy," said Geoffrey Marcy, who led Fischer's team.

"We are witnessing, I think, the emergence of a new era of human exploration," Marcy said. The newfound solar system exhibits orbital oddities and other unexpected properties that raise "profound questions" about where we fit in, he said, and whether our solar system may be "the result of some cosmic quirk of nature."

The new solar system does not appear hospitable to life. All three planets are whoppers, ranging from at least two-thrids to four times the mass of Jupiter--gravitational bullies that likely would have swept away any fledgling Earths.

And the data suggest they are giant gas balls, like Jupiter, with no surface to pool liquid water--a requirement for life as we know it. Even if they have rather Earthlike moons, Marcy said, they are in zones where any water would either boil off or freeze.

Two of the planets orbit their star--which is younger and hotter than our sun--at distances similar to those of Venus and Mars (77 million and 232 million miles, respectively). These distances are not where conventional theory predicted such large planets will reside. The innermost of the triplets, which was first detected in 1996, skims so close to the star that its "year"--one complete orbit--takes only 4.6 days.

Upsilon Andromedae is "up" in the daytime and therfore not viewable. By June, as Earth travels in its orbit around the sun, the star will appear again in our night sky.

Earth's home galaxy, the Milky way, contains 200 billion stars. This is the first time anyone has detected more than one planet around any of them. In fact, before this decade, astronomers had seen frustrated in their attempts to find any extra-solar planets at all.

But in a burst of discovery that began in 1995, planet hunters have detected 20 worlds around sunlike stars (including the triplets).

Astronomers said yesterday's announcement should kill lingering suspicions that these bodies are not really planets, but dim, failed stars known as brown dwarfs. Alan Boss of the Carnegie Institution, formerly among the skeptics, said: "One of the key ways to be sure we've really got planets is to find a system of planets. ... This is a major discovery."

The teams expressed relief and amazement at the remarkable agreement in their data. "This is such an extraordinary finding that you can't be obsolutely sure of it unless you have independent confirmation," said Robert Noyes, of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., a mener of the second team, which also included members from the High Altitude Observatory in Boulder, Colo.

Still, they went through rigorous checks and tests to eliminate all other explanations, before they dared go public.