 Galaxy rotation curve

A galaxy rotation curve gives circular speed as a function of radius. Its decomposition into stellar, gaseous, and dark-matter contributions is generally nonunique.

A galaxy rotation curve is a plot that shows how the orbital speeds of stars and gas in a galaxy vary with distance from the galaxy's center. Typically, the x-axis represents the distance from the galactic center (often measured in kiloparsecs or light-years), while the y-axis represents the orbital velocity (usually expressed in kilometers per second). In the context of galaxies, several key points can be highlighted: 1. **Expected vs.