Suppose that while analysing the optical spectrum of a galaxy, you observe the Hα absorption line to be located at a wavelength of 702 nm. Use the fact that the rest wavelength of this line is 656 nm to calculate the radial velocity of the galaxy in units of km/s. Then, use Hubbles Law (assuming the Hubble Constant to be H0 = 74 km/s/Mpc) to convert the radial velocity measurement into a distance estimate (in units of Mpc).

If a galaxy has an apparent radial velocity of 2000 km/s and the Hubble constant is 70 km/s/Mpc, how far away is the galaxy?

Suppose you have obtained spectra of several galaxies and have measuerd the observed wavelength of the H-Alpha line (rest wavelength = 656.3 nm) to be Galaxy 1: 658.1 nm. Galaxy 2: 667.1 nm. Galaxy 3: 677.6 nm. Assuming a Hubble Constant of 72.5 km/s/Mpc, calculate the distance to each of these galaxies (answer in Mpc)

A galaxy is observed to recede at speed 140 km/s. If the Hubble constant is 70 km/s/ Mpc, how far is the galaxy?

Using a value for Hubble's constant of 71 km/s per Mpc, find the distance of a galaxy that is receding at a velocity of 1600 km/s.

If a quasar is 1,640 times more luminous than an entire galaxy, what is the absolute magnitude of such a quasar? (Note: The absolute magnitude of the Milky Wag Galaxy is about -21. Use the formula for magnitude and flux ratio, Mv - Ma = 2.5log(Fa\Fb)).

Figure 2 shows the "rotation curve" of NGC 2742. It plots the “radial velocity (V)" (how fast material is moving either toward or away from us) that is measured for objects at different distances (R = radius") from the center of the galaxy. The center of the galaxy is at 0 kpc (kiloparsecs) with a speed of 9 km/sec away from us. (These velocities have been corrected for the observed tilt of the galaxy and represent true orbital velocities of the stars and gas.) 200 100 U4779 -100 As you can see, one side of the galaxy is moving with a negative velocity (spinning toward us), while the other side has a positive velocity (spinning away from us). Using Newton's gravity equation, we will be able to determine the gravitational mass of the entire galaxy and how the mass varies versus distance from the galaxy's center. -200 -8 8 -4 Radius (kpc) Read the following text carefully and follow the instructions: Select five radii spaced evenly from 0-10 kpc across the galaxy. Your selections should…

If a quasar is 2,000 times more luminous than an entire galaxy, what is the absolute magnitude of such a quasar?  Note: The absolute magnitude of the Milky Way Galaxy is about −21. Hint: Use the formula for magnitudes and flux ratios,