- An international team of astronomers has discovered eight
new extrasolar planets, at least two of which have circular orbits reminiscent
of the planets in our solar system.
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- The latest discoveries, reported Monday, bring the total
of known planets outside our solar system to around 80. More important,
they circular orbits reinforce a growing realization that at least some
other planetary systems are similar to our own.
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- Only a handful of previously discovered extrasolar planets
have showed similar orbital characteristics, whereas others have had orbits
that are more elliptical in shape.
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- "As our search continues, we're finding planets
in larger and larger orbits," said Steve Vogt of the Lick Observatory
at the University of California at Santa Cruz.
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- "Most of the planetary systems we've found have
looked like very distant relatives of the solar system -- no family likeness
at all," Vogt said. "Now we're starting to see something like
second cousins. In a few years' time we could be finding brothers and sisters."
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- Astronomers do not yet know for sure whether planets
around other stars form similarly to the planets in our solar system, or
if entirely different mechanisms might be at work. Researchers have not
yet found enough planets around enough stars, nor can they study them with
great enough resolution.
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- And most of the planets they have studied are very unlike
the planets near Earth. They are huge, typically larger than Jupiter, but
often orbit their stars as close as Mercury orbits our Sun.
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- The eight newly detected planets orbit their stars at
distances ranging from about 0.07 AU to 3 AU. (One AU, or astronomical
unit, is the distance from Earth to the Sun.) They range in mass from 0.8
to 10 times the mass of Jupiter, the largest planet in our solar system.
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- The study, one of many similar ones in recent months,
again illustrates that the pace of exoplanet discovery is increasing. The
first planet outside our solar system was detected in 1995.
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- Anne Kinney, director of NASA's Astronomy and Physics
Division, said the new finds presage an avalanche of new discoveries that
will allow researchers to begin to unravel some of the mysteries about
how planets and planetary systems form, in general.
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- The discovery was part of an ongoing search for planets
around the nearest 1,200 stars.
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- The astronomers use the Keck 10-meter telescope on Mauna
Kea, Hawaii, the Lick 3-meter telescope in Santa Cruz, and the 3.9-meter
Anglo-Australian Telescope in New South Wales, Australia. They employ a
pioneering technique called the wobble method, in which a star wobbles
space as it is affected by a planet's gravity.
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- The research was supported by the National Science Foundation
(NSF) and NASA.
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- http://www.space.com/scienceastronomy/astronomy/eight_planets_011015.html
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