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Solar system formation
Juramike
post Dec 4 2008, 05:53 PM
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So, if I skimmed that article correctly, it is "possible" that the sun could have a small iron core?


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tty
post Dec 4 2008, 06:00 PM
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Well it would be ionized iron gas, so I suppose it would kind of have spread out. rolleyes.gif
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dvandorn
post Dec 4 2008, 06:32 PM
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How much spreading can it do in an environment where the surrounding plasma is 150 times denser than water?

-the other Doug


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Guest_MichaelPoole_*
post Nov 30 2017, 08:53 PM
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QUOTE (dvandorn @ Dec 3 2008, 06:25 PM) *
Not failed planets -- spectacularly successful planets. wink.gif

Seriously, stars are formed, almost by definition, around the largest mass concentrations in a given stellar nursery nebula. What starts that process? For Population I stars, where there is almost nothing except gas in the birth nebula, obviously heavier elements play a very limited role, if any role at all. But for Population II stars, I've always wondered if the star begins with the largest collection of heavy elements (i.e., rocks) in the neighborhood, working from there to gather up enough gas to create such a super-gas-giant that the gas pressure in the interior becomes intense enough to support hydrogen fusion.

Looked at from the opposite side -- if a brown dwarf is a super-super Jupiter and is a failed star, and Jupiter-class planets require rocky cores to begin accretion, then doesn't it track that successful Pop II stars would start their accretion processes in the same manner as gas giants?

Something that has occurred to me more than once is that, if Pop II stars indeed accrete around rocky cores, what state do those cores achieve after several billion years of the temperatures and pressures at the core of their stars?

-the other Doug


Just because Jupiter has a massive core does not mean that all gas giant planets require a solid core to accrete around. In fact, I have read that what distinguishes a brown dwarf from a supermassive planet is that it does collapse straight from a star forming cloud without accreting like a planet.
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Gerald
post Nov 30 2017, 10:43 PM
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Well, first I think, that populations I and III stars appear to be confused in this discussion.
Then, stars are usually assumed to be the product of the collapse of a dense molecular cloud by a Jeans instability.
For Brown Dwarfs, both scenarios have been considered, IIRC, a rapid collapse as well as growth starting from a rocky core. The question is, whether there is a sharp boundary between these two scenarios.
But assuming, that a rocky or a metal core would survive star formation requires at least some considerable investigation. Some stars are assumed to be fully convective, others are assumed to form a shell structure, when aging.
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