| Topic: |
Religions > Atheism |
| User: |
"Meteorite Debris" |
| Date: |
15 Jul 2005 12:23:04 AM |
| Object: |
OT - Gas giant planets form quicker than thought |
http://www.abc.net.au/science/news/stories/s737059.htm
Gas giant planets form quicker than thought
Friday, 29 November 2002
Gas giants form more like small stars, according to a new study
Gas giants like Jupiter may have formed in less than a thousand years
- a lot faster than originally thought, according to a new simulation
of planet formation by Italian and Canadian planetary scientists.
The study by Dr Lucio Mayer of the University of Washington in Seattle
and Canadian colleagues is published in this week's issue of the
journal Science.
According to the standard 'core accretion' model, planets grow through
the clumping together of material in disks of gas and dust whirling
around young stars. In this scenario, a gas giant such as Jupiter or
Saturn would take more than a million years to form.
But Mayer and his colleagues found that 'protoplanets' could arise in
less than a thousand years, as long as the swirling accretion disk
remained cold enough for long enough.
Their conclusion was drawn from high-resolution computer simulations
of the formation of planets from the cosmic debris circling a young
star. And it supports a competing theory that giant gas planets form
more like stars: from the fragmentation of molecular clouds.
According to Dr Charles Lineweaver, an astrophysicist at the
University of New South Wales in Sydney, the paper lends support to
the minority theory that gas giants like Jupiter form more like small
stars, rather than the way rocky planets like Earth and Mars do.
However, the models - described by Lineweaver as 'bottom up' (more
planet-like) and 'top down' (more star-like) - were both relevant to
planet formation.
"Little planets like Earth and Mars certainly formed from a 'bottom
up' [process], while big planets like Jupiter probably formed from a
mixture of 'bottom up' and 'top down'," Lineweaver told ABC Science
Online. "In other words, [gas giants] are half-way between planets and
stars."
The study helps explain why so many Jupiter-sized 'extrasolar' planets
have been discovered orbiting other stars. These belong to planetary
systems very unlike ours - with Jupiter-sized planets as close to
their parent star as Mercury is to our Sun. The simulation suggests
they are formed quickly and far away from the parent star, but
eventually migrate in toward the centre.
Lineweaver described the study as important. "We cannot go back and
see how our Solar System formed," he said. "We're all waiting for [new
orbiting telescopes] that will be able to see solar systems like ours,
but that won't happen for another 10 years. In the meantime,
simulations allow us to infer things about how our Solar System
formed."
The simulation was significant because it had "unprecedented
resolution", he said, with the largest number of particles in a debris
disk ever modelled, giving the 'top down' theory much more authority.
Anna Salleh - ABC Science Online
--
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| User: "Uncle Buck" |
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| Title: Re: OT - Gas giant planets form quicker than thought |
16 Jul 2005 06:37:04 AM |
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On Fri, 15 Jul 2005 14:53:04 +0930, Meteorite Debris
<epicurus1@YOUR_SHOESoptusnet.com.au> wrote:
http://www.abc.net.au/science/news/stories/s737059.htm
Gas giant planets form quicker than thought
Friday, 29 November 2002
Gas giants form more like small stars, according to a new study
Gas giants like Jupiter may have formed in less than a thousand years
- a lot faster than originally thought, according to a new simulation
of planet formation by Italian and Canadian planetary scientists.
If that's so, is it possible that the Jupiter & Saturn we see today
are notably different from the Jupiter & Saturn that were here a
thousand years ago? Or is our solar system not conducive to such
dramatic changes in gas giants? :-? Interesting.
--
L8r,
Uncle Buck
\~------------0-0-0-O-o*O*o*O*o-O-0-0-0------------~/
There are two main things we must concern ourselves
with in life: Our "to Do" list and our "do-do" list.
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