According to the Tully-Fisher relation, the rotational speed of a spiral galaxy, as indicated bythe broadening of spectral lines, allows us to determine the galaxy's
A)luminosity.
B)color.
C)redshift.
D)mass.
E)shape.

Question

Quizplus · Accepted Answer

The Tully-Fisher relation is an empirical relationship between the luminosity of a spiral galaxy and its rotational velocity. It suggests that galaxies with higher rotational speeds have greater luminosity, allowing astronomers to estimate the luminosity of a galaxy based on its rotational speed.

According to the Tully-Fisher Relation, the Rotational Speed of a Spiral