Here is a CNN article which mentions a new theory that our solar system is
rare and formed rapidly by a gamma-ray burst:
"The flood of energy melted primordial dust grains, seeded the formation
of meteorites and helped Earth and the other rocky planets coalesce quickly
from a disc of gas and dust...Pre-planetary beads, called chondrules, likely
formed in a matter of minutes 4.5 billion years ago when the radiation burst
seared the disc spinning around the sun...the blast occurred within 300 light
years from the sun and flooded the disc with enough energy to fuse
material weighing as much as 100 times our Earth into droplets that cooled
into chondrules...The theory implies that solar systems like ours are rare --
chondrules likely settle quickly and may or may not become planets."
If this holds up would be yet more evidence that our solar system is special
and that life exists only on Earth.
Steve
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http://www.cnn.com/TECH/space/9909/10/planet.birth/index.html
New theory: Gamma-ray blast spawned planets
Supernova 1997ce, as imaged by the Hubble Space Telescope. Two Irish
astrophysicists believe gamma rays emitted by the an explosion like this one
may have been a catalyst for planet formation in our solar system.
September 10, 1999 Web posted at: 4:50 p.m. EDT (2050 GMT)
(CNN) -- A violent blast of gamma-rays may have sparked the formation of
our solar system's rocky planets within minutes, two Irish astrophysicists
say.
The flood of energy melted primordial dust grains, seeded the formation of
meteorites and helped Earth and the other rocky planets coalesce quickly
from a disc of gas and dust, say Brian McBreen and Lorraine Hanlon of
University College Dublin.
Pre-planetary beads, called chondrules, likely formed in a matter of minutes
4.5 billion years ago when the radiation burst seared the disc spinning
around the sun, they say.
The astrophysicists think the blast occurred within 300 light years from the
sun and flooded the disc with enough energy to fuse material weighing as
much as 100 times our Earth into droplets that cooled into chondrules.
The iron-rich chondrules then soaked up gamma rays and X-rays, McBreen
said.
McBreen and Hanlon's theory was reported in the latest issue of New
Scientist magazine.
The theory implies that solar systems like ours are rare -- chondrules likely
settle quickly and may or may not become planets.
"Forming chondrules really is a long-standing problem, so if this
mechanism accounts for them, that would be pretty fantastic," said Alan
Boss, an astrophysicist at the Carnegie Institution in Washington.
Astronomers have long wondered what caused clumps of dust circling our
young sun to melt into rocky beads rich in iron and silicon, or the
chondrules that make up the bulk of meteorites.
The burst, thought to be one of the most powerful of its kind in the
universe's history, could be the result of a stellar explosion called a
supernova.
But Boss reportedly was unsure that such an unlikely event could be
responsible for something as crucial as the formation of our solar system.
"I don't think you'd want to invoke it unless it takes care of everything," he
said.
McBreen and Hanlon plan to publish their results in an upcoming issue of
Astronomy and Astrophysics.
[...]
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"To suppose that the evolution of the wonderfully adapted biological
mechanisms has depended only on a selection out of a haphazard set of
variations, each produced by blind chance, is like suggesting that if we
went on throwing bricks together into heaps, we should eventually be able
to choose ourselves the most desirable house." (Waddington C.H., "The
Listener", London, 13 November 1952, in Koestler A., "The Ghost in the
Machine", [1967], Arkana: London, 1989, reprint, p127).
Stephen E. Jones | sejones@iinet.net.au | http://www.iinet.net.au/~sejones
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