
Elegant New Theory Explains Origin Of Asteroid Belt - J3L2404
http://www.technologyreview.com/blog/arxiv/26119/?p1=Blogs
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fhars
This theory elegantly explains the structue of one of the known planetary
systems, but as far as I can tell forbids the structure of most other known
planetary systems which contain at least one "hot jupiter". From a theory that
relies on the impossibility of gas giants staying gas giants near a star, I'd
expect some arguments as to why all the observed gas giants that are extremely
close to their stars do not invalidate it.

Is this just a sloppy writeup, or do they really ignore that?

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hugh3
_From a theory that relies on the impossibility of gas giants staying gas
giants near a star, I'd expect some arguments as to why all the observed gas
giants that are extremely close to their stars do not invalidate it._

I read the preprint, but it's a little iffy on the idea of how the removal of
the outer layers is supposed to work. But I think the idea is that a small gas
giant would lose its outer layers if brought in from the outer solar system,
while a Jupiter-sized one wouldn't.

Still, the preprint makes no reference to hot Jupiters whatsoever, which seems
to be a major oversight. It's no good crowing about how your model explains
one planetary system without even mentioning what it says about others.

I don't much like this model, myself.

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iwr
So planets would tend to form more from the aggregation of gas rather than
rocks or dust (then accumulate the other kinds of matter in the new gaseous
body). Does this new model also propose that planets formed further out than
previously believed? ("in excess of 50au" means further out than Pluto)

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DougWebb
If "all the planets rotate in the same direction" because they picked up that
momentum from the original cloud, then what happened to Venus? Why does it
spin the other way?

This theory picks out one radius, where the belt is, as special. I wonder if
it can account for the stable orbits of the other planets too. They're oddly
regular. I've always wondered if their arrangement is related in any way to
the arrangement of electron shells around atoms, which are also very regular
becauuse of the electron energy states.

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iwr
While retrograde, it's only "weakly" so in that it has a very slow rotation
period (1 solar year == 2 solar days).

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Cushman
Does this imply that each of the gas giants has an Earth-like core buried in
the gas, surrounded by an orbiting swarm of rocky asteroids?

Because that would be _awesome_.

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jerf
"Earth-like" is probably the wrong idea; I'd rather say "rocky". I wouldn't
care to guarantee much else about that core would be Earth-like, from the
chemistry to the composition to the way it moves or anything else.

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sanj
How much time does the planetary core spend inside the embryonic cloud?

It seems like if it spent much time there, it should shows signs of the
crushing gravitational pull required for it to maintain a large gaseous
atmosphere during birth.

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hugh3
_How much time does the planetary core spend inside the embryonic cloud?_

The lifetime of the protosolar nebula is pretty short -- only a million years
or so.

 _It seems like if it spent much time there, it should shows signs of the
crushing gravitational pull required for it to maintain a large gaseous
atmosphere during birth._

I'm not sure what you mean here.

