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How fast are stars orbit speed?

  1. Jun 30, 2012 #1
    1.
    How fast are stars orbit speed in elliptical galaxies (from and to)

    2.
    How big differences are there typical between
    Perigalacticon and Apogalacticon in a. elliptical galaxies and b. spiral galaxies?
     
  2. jcsd
  3. Jun 30, 2012 #2

    mfb

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    Staff: Mentor

    1. It depends on the mass of the galaxies and the distance of the star. In addition, not all orbits are circular, the velocity can vary with time.
    The sun has an orbital velocity of ~200km/s. While other stars have different speeds, it should give you some idea about the orders of magnitude involved.

    2. There probably exists some study somewhere. I think the interesting graph would be two-dimensional, plotting both values at the same time (or semi-major axis and excentricity) for all stars and showing their density in this area.
     
  4. Jun 30, 2012 #3

    phinds

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    Just another thing to think about: the stars closest in to the super-massive black hole at the center of the milky way orbit around it at staggeringly high speeds relative to those far away from its influence.
     
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