A Neptune-sized planet likely got the boot from the solar system some 3.9 billion years ago, suggests an analysis.
Our solar system now includes four giant planets, Jupiter, Saturn, Uranus and Neptune. Astrophysicists have long puzzled how they arose from the debris disc that surrounded the sun about 4.6 billion years ago when the sun was born.
In a series of 6,000 simulations of the early solar system's growth, David Nesvorny of the Southwest Research Institute in Boulder, Colo., reports on the physics arXiv database that a solar system starting with five giant planets was 10 times more likely to lead to today's configuration of planets, rather than one with just today's familiar four big'uns.
In the most successful simulations, the four giant plants start tightly packed with a fifth Neptune-like "ice giant" planet, orbiting about 15 times further from the sun than the Earth. Jupiter and Saturn send the lighter planets out further, to disrupt the comet belt near Pluto.
In a dramatic finale, the fifth ice giant is "ejected" completely from the solar system by a close encounter with Jupiter, the King of Planets. "This possibility appears to be conceivable in view of the recent discovery of a large number free-floating planets in interstellar space, which indicates that planet ejection should be common," concludes the study.
Source : http://content.usatoday.com/communities/sciencefair/post/2011/09/study-solar-system-ejected-giant-planet-early-on/1
NASA
In a series of 6,000 simulations of the early solar system's growth, David Nesvorny of the Southwest Research Institute in Boulder, Colo., reports on the physics arXiv database that a solar system starting with five giant planets was 10 times more likely to lead to today's configuration of planets, rather than one with just today's familiar four big'uns.
"Studies of giant planets' interaction with a protoplanetary gas disk show that their orbits radially migrate, and typically achieve a compact configuration, in which pairs of the neighbor planets are locked in the mean motion resonances. The resonant planetary systems emerging from protoplanetary disks can become dynamically unstable after the gas disappears, leading to a phase when planets scatter off of each other. This model can explain the observed resonant exoplanets, commonly large exoplanet eccentricities, and microlensing data that show evidence for a large number of planets that are free-floating in interstellar space.Indeed, the early solar system likely looked a lot different than today, the report suggests.
The solar system, with the widely spaced and nearly circular orbits of the giant planets, bears little resemblance to the bulk of known exoplanets," says the study.
In the most successful simulations, the four giant plants start tightly packed with a fifth Neptune-like "ice giant" planet, orbiting about 15 times further from the sun than the Earth. Jupiter and Saturn send the lighter planets out further, to disrupt the comet belt near Pluto.
In a dramatic finale, the fifth ice giant is "ejected" completely from the solar system by a close encounter with Jupiter, the King of Planets. "This possibility appears to be conceivable in view of the recent discovery of a large number free-floating planets in interstellar space, which indicates that planet ejection should be common," concludes the study.
Source : http://content.usatoday.com/communities/sciencefair/post/2011/09/study-solar-system-ejected-giant-planet-early-on/1
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