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Animation/visualization of galactic rotation rates (dark matter)

  1. Jun 13, 2008 #1
    I was reading the wiki page on dark matter, and have trouble visualizing how galaxies keep their shape if most of the stars rotate at the same rate. If I try to imagine this (ie: without any sort of math modelling of the gravity interactions involved) I picture everything just merging into a big amorphous disk instead of shapes like spirals.

    Does anybody know of a nice animation or visualization of long term effects of a gravity model of a spiral galaxy? Ideally I'd like to see how the rotation would look over time with and without the dark matter distribution.
  2. jcsd
  3. Jun 16, 2008 #2
    I posted this on an astronomy forum that I found associated with the awesome "astronomy cast" podcasts. There I was recommended to look for info on "spiral density waves in galaxies" and found something pretty close to what I was looking for. Will mark thread as solved.
  4. Jun 17, 2008 #3
    I don't think these are exactly what you are looking for but these might help.

    Formation of a spiral galaxy:

    A Galaxy is born:

    Formation of a Star Cluster:

    .. and of course, the Dark Matter Bullet Cluster video:
    http://www.slac.stanford.edu/~jwise/research/movies/HiResBullet.mov [Broken]
    Last edited by a moderator: May 3, 2017
  5. Jun 17, 2008 #4
    thanks, those were interesting to watch. It's kind of amazing to see the dynamics of such large scale structures visualized. Looking at pictures of galaxies I never thought of them as very dynamic structures, whereas there's a massive amount of complex motion involved, with little galaxies forming and being absorbed. Modelling one of these must be interesting. Even just considering gravitational effects it's a big calculation, but when you add in the facts that each of the "points" is potentially a big nuclear engine it's quite phenomenal!
  6. Jun 17, 2008 #5
    Yea, I've saved a few links because I too, thought they were extremely interesting..
    Check these ones out.. also, you can do a search on Youtube using keywords such as "galaxy formation", Simulation of ... " and the like..

    Some more nice ones that I've found...



  7. Jun 20, 2008 #6
    Note that although stars orbit at the same speed, that doesn't mean they rotate at the same angular velocity, so stars closer to the centre still have shorter orbital periods than stars further out.

    Also, the spiral pattern is generally considered to be a density wave. Stars and gas actually pass through arms, and the gas gets temporarily compressed as it passes through, which causes the star formation that makes spiral arms bright with lots of young O/B stars. Does that help you to visualise what's going on?

    If you google "galaxy animation" you should find a bunch pretty easily. That or search for universities that do galaxy simulations, and find the animations on their webpages.
  8. Jun 20, 2008 #7
    Yes, thank you Dave.
  9. Jun 20, 2008 #8
    While not video, the book Galactic Dynamics (2008) is very helpful. It shows how the spirals and whatnot form due to something that looks like traffic jams. It's pretty cool stuff.
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