What made our solar nebula spin?

Discussion in 'Astronomy, Exobiology, & Cosmology' started by Dmitri, Apr 15, 2002.

  1. Dmitri Registered Member

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    What gave our (and any other) solar system the spinning momentum? I have tried to do the research on my own, but was unable to come up with any solid conclusions. May be some of you, bright minds, can give me an explanation.

    It seems to me that there is no definite answer, and I will welcome any speculations on your part.
     
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  3. wet1 Wanderer Registered Senior Member

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    Welcome to sciforums, Dmitri.


    An obvious, and seemingly simple question for astronomers is, "How did the Earth form?" While the basic scenario for planet formation is widely accepted, the details are far from understood.
    The planets in the solar system presumably formed in situ, that is, in place, during the formation of the sun. Stars almost always form within an accretion disc. Accretion discs develop most of the time when matter is falling together due to gravitational attraction. The disc occurs because the matter almost always has some angular momentum. Energy is dissipated by radiation of heat and light, but radiation cannot dissipate angular momentum, and the matter is forced into orbit about the central mass concentration. Angular momentum can be pushed outward by viscous exchange and magnetic braking into lower mass regions, and allow material to reach the center.

    For the rest of the article:*here*

    As the cloud or accretion disc condenses by gravity, the angular momentum is conserved by an increase in spin. Much the same as a skater, doing a spin tucks in the arms to increase the speed of the spin. This happens naturally in the process of system births.


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    All stars and stellar systems develop from clouds of dust and gas such as in the above picture.

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    Gravity begins to draw material towards the center and begins the star formation process. In addition there will be local clusters within the cloud that begain to clump and start the planet formation.

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    The process continues. The planets continue to gell out of the cloud. The protostar achieves ignition. the light from the star starts pushing the uncollected dust and gas out of the system.

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    The inner planets are now fully formed while the process continues on the outermost planets. The clearing around the star continues...

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    Completely developed system. The majority of the dust has now either been used in developing the system or has been pushed out of it.

    The pictures come from: http://cougar.jpl.nasa.gov
     
    Last edited: Apr 15, 2002
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  5. Dmitri Registered Member

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    Thank you

    Thank you so much oh Wet one.... it was very nice of you to spend so much time on that explanation, but it still doesn't answer that which really bothers me

    Although I can see how matter can collect into a proto-sun, creating a massive gravitational center, and any matter that has momentum happens to be passing by gets cought in it creating the disk.... that's all clear to me

    What I don't understand is where THAT matter gets it's momentum! the BIG bang itself? other near-by explosions?
     
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  7. wet1 Wanderer Registered Senior Member

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    Ah, I see what bothers you.

    Most of the dust/gas clouds start with some motion already present to some extent. The collapsing of the cloud increases the spin as it can not be shed off. (Conservation of energy)
     
  8. kmguru Staff Member

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    Something else should be kept in mind that once one galaxy is spinning, it has an effect on other galaxies. There is an angulat momentum exchange between galaxies. Somebody did observations using the Arecibo telescope of Pisces-Perseus Supercluster (54 galaxies). The results found to be a strong corelation of spin vectors between galaxies.

    If you keep going back to big bang, may be a massive black hole starts the spin and aligns subsequent formation of the young galaxies?
     
  9. Dmitri Registered Member

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    now we are getting somewhere

    wet1, you are saying all gases are starting off with some motion to some extent and because of the well effect, the gases speed up their journey on the way to certain death (the new born sun) fallowing the decaying orbit (unless angular momentum = gravity forces, that's when you get stable orbits)...... that's where I get lost....... WHERE do the gases get their original motion?

    if that motion came from the big bang itself it should be uniform and from my point of view all the matter should be simply heading away from the center of the "bang" uniformly without any real interaction

    kmguru suggests the galaxy model where galaxies effect other galaxies, are you implying that the same is true for newborn solar systems?
     
  10. Adam §Þ@ç€ MØnk€¥ Registered Senior Member

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    When all that mass in the cloud/blob of dust and gas tha became our system began pulling into a lump, it all started moving in, and that motion and momentum did not just vanish. The lump/blob/cloud would have been turning all sorts of ways at first. But some time it all settled into turning more one way than others, and kept on going until it was a disc.
     
  11. kmguru Staff Member

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    It could be the bath tub effect - turbulent flow vs laminar flow of fluid medium....with temperature and pressure differentials added.
     
  12. wet1 Wanderer Registered Senior Member

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    Large clumps and clouds of dust and gas get some of their motion by gravational attraction. As clumps or clouds are attracted to and move past each other this helps to impart some movement in the mass of the objects passing each other. This is thought to be why there is motion in most of the clouds. Your question intrigued me and I spent some time looking for some answers myself. These clouds are not what you would think of as dense but there is still enough there by size for gravity to have an effect.
     
    Last edited: Apr 16, 2002
  13. Dmitri Registered Member

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    THANK YOU!!!!!!!!!!!!!!!!!!!

    Thank you both wet1 and kmguru, I think you've just both answered my question! I certainly like the temperature differential idea, I can see how it can be applied, although it is less likely then the other one....

    yes, of course..... particles in the cloud itself interacting - at first fairly random attraction process, less dense parts of the cloud being pulled in into denser ones, if a few dense spots develop, you get everything you wanted - starting from you slingshot effect, eccelerating movments of certain parts of the cloud to your elliptical orbits! but because the process of attraction is fairly random you get your twin star systems and enormous gas giants that JUST didn't make it in mass to start off nuclear reaction, but I am sure there some that did somewhere.... imagine star systems with suns between planets! wouldn't it be great if Jupiter was a star (a small one ?

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