Question

question 8
1 pts
we can estimate the mass of the galaxy from observations of
the amount of light received in different parts of the electromagnetic spectrum
radial velocities, proper motions, and distances of stars
other spiral galaxies
globular cluster densities
black holes, neutron stars, and white dwarfs

Explanation:

To estimate the mass of the Galaxy, we use the motions of stars. The radial velocities (speed towards or away from us), proper motions (angular motion on the sky), and distances of stars are used in gravitational - dynamic models. The amount of light (related to luminosity) doesn't directly give mass (as different stars have different mass - luminosity relations and there is dark matter which doesn't emit light). Observing other spiral galaxies or globular cluster densities or black holes/neutron stars/white dwarfs (which are a small fraction of the Galaxy's mass) is not the primary way to estimate the Galaxy's total mass.

Answer:

radial velocities, proper motions, and distances of stars