Which observation of elliptical galaxies provides a measure of the relative motions of stars and of the degree of randomness of their motions within these galaxies?

Question

Quizplus · Accepted Answer

The broadening of spectral lines in the spectra of elliptical galaxies provides a measure of the relative motions of stars and the degree of randomness of their motions within these galaxies. This is because the broadening is caused by the Doppler effect, which reflects the motions of stars towards or away from us, and the degree of broadening reflects the level of random motion among the stars.

Which Observation of Elliptical Galaxies Provides a Measure of the Relative