turbo-1 said:Just google on "galactic rotation curves" and you'll get what you want.
A galaxy rotation curve is a graph that shows the rotational velocity of stars and gas in a galaxy as a function of their distance from the galactic center. It is typically a flat curve, indicating that the velocity of objects in the galaxy remains constant at larger distances from the center.
Graphs of galaxy rotation curves are important because they provide evidence for the existence of dark matter. In most galaxies, the observed rotational velocities are much higher than what would be expected based on the visible matter in the galaxy. This suggests the presence of an invisible mass, or dark matter, which is responsible for the observed rotation curve.
Galaxy rotation curves are measured using a variety of techniques, including radio astronomy, optical spectroscopy, and gravitational lensing. These methods allow scientists to measure the velocities of stars and gas in a galaxy at different distances from the center and create a graph of the rotation curve.
Studying galaxy rotation curves can provide valuable insights into the structure and composition of galaxies. It can help scientists understand the distribution of matter within galaxies, the presence of dark matter, and the dynamics of galactic interactions. This information can also be used to test and refine theories of gravity and cosmology.
No, not all galaxy rotation curves are the same. While most galaxies have flat rotation curves, some galaxies exhibit different shapes, such as rising or falling curves. This can be attributed to different factors, such as the distribution of visible matter, the presence of dark matter, or the effects of galaxy interactions.