Answer to Question #202925 in Astronomy | Astrophysics for Prachi

Question

Discuss the rotation curve of our Galaxy. What inferences can be drawn from it about the structure of our Galaxy?

Answer 1

The rotation curve is the dependence of the circular velocity on the galactocentric distance. The rotation curve of the Galaxy is quite complex. In the inner part of the Galaxy rotation curve rises as for a rigid body rotation (due to bulge or bar), then it reaches a maximum value and then has a plato. Such a curve is observed in another spiral galaxies. Such a form means that not the total mass of the Galaxy is situated at the central part, because in such a case the rotation curve will have a keplerian form (a prominent decrease for a large distances). The existence of a plato means that a huge mass is in the outer part of the Galaxy, may be it is a halo of dark matter.