The Doppler effect red or blue shift of spectral lines allows determination of the radial component of the velocity. The differential rotation of the Sun. The 11-year sunspot cycle. The Properties of Stars Parallax - the basic distance measurement technique of astronomy. The dependence of the apparent brightness of a star on its distance, radius, and temperature.
Color is related to temperature.
The main sequence Most stars lie on it in a color magnitude diagram. It consists of stars burning Hydrogen to Helium in their cores. The motion of binary stars follows a generalized version of Kepler's laws. Each star orbits the center of mass. Bright, massive stars are very rare.