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Why gas giants were created far from the Sun?

  1. Jan 9, 2008 #1
    Some of my friends are arguing how gas giants were created far from the Sun, while the rocky planets were in the inner orbits.
    One of the ideas is at first they were all the same: gas giants, then the solar wind blew the outer layers of the inners and they became rocky. How do you think of this?
     
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  3. Jan 9, 2008 #2

    Astronuc

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    I guess it's a matter of how (and how much) the sun and planets formed with respect to each other from the initial cloud, but it would seem plausible that the denser parts (dust) was pulled closer into the center of gravity while the lighter elements (gases) were further out.
     
  4. Jan 9, 2008 #3
    Thanks for your input. My idea is nearly the same: at first the solar wind blew the disk out and mostly the gas was influenced more, the dust stayed closer before the planets were created. In a recent article in space.com, the gas and dust disk is believed closer to the sun at first.
     
  5. Jan 9, 2008 #4

    Kurdt

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    The accepted idea was that the inner part of the solar system was too hot for ice and gas which got blown further away from the newly forming sun. Strong solar winds also played a part. Lately with the discovery of many gas giant exoplanets in close proximity to parent stars those ideas have been cast into a little bit of doubt. I still think the ideas are pretty solid since the gas giants proximity to parent stars can be explained by other factors such as gravitational interactions.
     
  6. Jan 9, 2008 #5
    For the reason of discovery of quite many gas giants close to their parent stars, I should think it is because we so far have not been able to observe rocky small planets in such distances. There may be many more terrestrial planets out there.
     
  7. Jan 9, 2008 #6

    Kurdt

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    Thats entirely true. It has still forced us to reconsider solar system formation ideas however since at one time gas giants close to parent stars would not have been thought possible.
     
  8. Jan 9, 2008 #7
    So, with all the information available by ..now, how do you think of solar system planets creation:
    1) They were all created as gas giants and then the inner ones were losing thick atmospheres over time. Or 2) they were created just as they are today?

    At first I followed the 2nd reason, now I am confused.
     
  9. Jan 9, 2008 #8

    Kurdt

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    Like I stated in my first post I still think the original ideas are pretty solid. There are other ways of explaining how gas giants would get so close to the parent star. When any star is first formed and initially ignites and starts nuclear reactions the solar winds are very powerful. This blows most of the accreting matter to the edges of the system leaving only the denser materials behind.
     
  10. Jan 9, 2008 #9
    In the current theories of planet formation, gas giants need to form out beyond the "snow line" of the stellar dust disk. The snow line is the point that the temperature of the dust disk is low enough for volatile ices to freeze out as solids. Gas giants need this for simple mass considerations; the center of Jupiter is about 10-15 Earth masses worth of rock and ice. There is not enough material in the inner portions of the disk to allow the formation of a planetary core this large.

    You can calculate that directly by looking at the expected densities of stellar dust disks.

    The idea for how gas giants get close to their parent stars, where we observe them in other systems, is that after formation in the outer parts of the disk they migrate inwards.
     
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