Anonymous asked in Science & MathematicsAstronomy & Space · 9 years ago

Rotation Curve of MW galaxy?

What is meant by the rotation curve of the milky way galaxy. Does the rotation curve imply that we're rotating as a solid body... I'm not quite sure as to what a rotation curve is... Can you recommend sites of videos that I can watch?

Please and thank you

1 Answer

  • 9 years ago
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    The rotation curve of a galaxy has nothing to do with whether it is a solid body or not. The rotation curve describes the rotational velocity as a function of radius. How fast a star orbits the center of the galaxy depends on how much mass is interior to it's orbit. The more mass, the faster it orbits. The curve itself looks just like this:

    The x-axis represents distance the star is from the center and the y-axis represents the speed at which it orbits. What the A and B curve means is a difference story. The A curve was a theoretical calculation before we knew about Dark Matter. The B curve is what we actually measure and the curve looks like that because of Dark Matter.

    Just as a note, our galaxy does not rotate as a solid body, it has differential rotation.

    Source(s): Astrophysics Degree
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