Solar system formation |
Solar system formation |
Dec 3 2008, 05:16 AM
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Senior Member Group: Members Posts: 3419 Joined: 9-February 04 From: Minneapolis, MN, USA Member No.: 15 |
Here is a recent article in space.com (I tried to link to this a few days ago, but it disappeared from the space.com archives...today it's back) about how Jupiter may have a much bigger core (14-16 Earth masses of rock!) than previously proposed. Previous predictions ranged from a core of 7 Earth masses of rock to no core at all. Juno should help nail down the absolute size of the core, and therefore, whether a rock core was required for the initial accretion. Which came first: gas or rock? And if rock is required to initiate accretion of gas giants... what about stars? -the other Doug (This discussion was originally in the Juno thread but was moved to a separate topic - moderator) -------------------- “The trouble ain't that there is too many fools, but that the lightning ain't distributed right.” -Mark Twain
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Dec 3 2008, 05:25 PM
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Senior Member Group: Members Posts: 3419 Joined: 9-February 04 From: Minneapolis, MN, USA Member No.: 15 |
Not failed planets -- spectacularly successful planets.
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 -------------------- “The trouble ain't that there is too many fools, but that the lightning ain't distributed right.” -Mark Twain
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Dec 3 2008, 07:16 PM
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Senior Member Group: Members Posts: 1074 Joined: 21-September 07 From: Québec, Canada Member No.: 3908 |
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? Once the nuclear fusion reactions start inside a star, wouldn't the rocky core, if one is present, be eventually vaporized and become mixed with the gas? |
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