BRIDGEPORT, WV (S-M) - Astronomers using telescopes at Lick and Keck Observatories have found a fifth planet around the star 55 Cancri, setting a record for the most known planets around a star other than the Sun.
"It is amazing to see our ability to detect extrasolar planets growing," said Alan Stern, associate administrator for the Science Mission Directorate. "We are finding solar systems with a richness of planets and a variety of planetary types comparable to our own."
The new planet is the fourth from its star and orbits in the "habitable zone," a distance from the star where temperatures are warm enough for water to remain a liquid, thus raising the possibility that life could form there. However, the planet is quite unlike our own, and is likely a gas giant with a mass of about 45 times that of Earth. Still, if the planet has any moons then they could be possible homes for life.
Debra Fischer, an astronomer at San Francisco State University, said "The gas-giant planets in our solar system all have large moons. If there is a moon orbiting this new, massive planet, it might have pools of liquid water on a rocky surface."
Fischer and a team of collaborators discovered this planet after careful observation of 2,000 nearby stars with the Shane telescope at Lick Observatory located on Mt. Hamilton, east of San Jose, Calif., and the W.M. Keck Observatory in Mauna Kea, Hawaii. The planet was not seen directly, but was instead detected by the Doppler technique. As the planet orbits 55 Cancri, it causes the star to wobble slightly, and these wobbles show up in slight frequency shifts in the star's light.
"Discovering these five planets took us 18 years of continuous observations at Lick Observatory, starting before any extrasolar planets were known anywhere in the universe," said Geoff Marcy, of the University of California at Berkeley. "But finding five extrasolar planets orbiting a star is only one small step. Earth-like planets are the next destination." - GW
Copyright 2007 Starry Mirror and Glen Ward
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ASTRONOMERS FIND FIFTH PLANET AROUND 55 CANCRI - NOVEMBER 08