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The planetary system is believed to be the largest ever detected beyond the sun.
Astronomers have confirmed the presence of five planets and have tantalising evidence of two more.
The distance of the planets from their parent star follow a regular pattern, similar to that seen in our own solar system.
”We have found what is most likely the system with the most planets yet discovered,” said Dr Christophe Lovis, who led the European southern Observatory (ESO) scientists.
”This remarkable discovery also highlights the fact that we are now entering a new era in exoplanet research: the study of complex planetary systems and not just of individual planets.
”Studies of planetary motions in the new system reveal complex gravitational interactions between the planets and give us insights into the long-term evolution of the system.”
The parent star, known as HD 10180, lies in the southern constellation of Hydrus 127 light years away.
Astronomers patiently studied it for six years using a planet-finding instrument called the HARPS spectrograph, attached to ESO’s 3.6 metre (11.8ft) telescope at La Silla, Chile.
From 190 individual HARPS measurements, they were able to detect tiny wobbles in the star’s motion caused by the gravitational tugs of its planets.
The five strongest signals corresponded to planets with Neptune-like masses, between 13 and 25 times that of the Earth.
These planets, with orbit periods ranging from six to 600 days, are separated from their star at 0.06 to 1.4 times the distance between the Earth and sun.
Dr Lovis added: ”We also have good reasons to believe that two other planets are present. One would be a Saturn-like planet (with a minimum mass of 65 Earth masses) orbiting in 2,200 days. The other would be the least massive exoplanet ever discovered, with a mass of about 1.4 times that of the Earth.
”It is very close to its host star, at just 2 per cent of the Earth-sun distance. One ‘year’ on this planet would last only 1.18 Earth days.”
The planet would be rocky, like the Earth, but probably far too hot to sustain life.
With at least five Neptune-sized planets circling inside an orbit equivalent to that of Mars, the HD 10180 system has a more populated inner region than our solar system.
So far astronomers have found 15 systems containing at least three planets.
The last record holder was 55 Cancri, which has a total of five planets including two gas giants.
Details of the discovery were presented today at an exoplanet meeting at the Haute-Provence Observatory in south-east France.
A paper on the research has been submitted to the journal Astronomy And Astrophysics.

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This entry was posted on 星期三, 八月 25th, 2010 at 8:46 上午 and is filed under Global. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.