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Calculating a rotation curve

  1. Mar 3, 2015 #1


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    I hope this is in the right forum.
    I'm trying to see how to calculate rotation curves for a spiral galaxy.
    The data I have is brightness profile (mag/arcsec^2) and observed rotation curve - to see how it fits.
    from what I found I need the total mass, and for that I need the surface mass density.
    I couldn't find how to convert the brightness profile to mass density.
    I can probably let matlab integrate the spline of the brightness profile, but that's not the mass density, so it wouldn't give me the mass I need.

    Would appreciate help.
    References to books (preferably with solved exercises) or other material are very welcome.

  2. jcsd
  3. Mar 7, 2015 #2
  4. Mar 8, 2015 #3


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    no, but thanks for trying.
    I think I need to clarify what I'm asking.
    The steps I found for calculating an RC are:
    get the intensity profile
    use that to find the mass distribution
    use mass distribution to find g
    calculate rotation curve.

    I have the luminosity profile. (\mu). The units are mag/pc^2.
    I need to convert it to mass distribution \SIGMA r (M/ pc^2).
    how do I do that? I know I'm suppose to assume mass to light ratio but how exactly?
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