Question

Suppose that you have obtained spectra of several galaxies and have measured the observed wavelength of the H-alpha line (rest wavelength = 656.3nm) to be:

Galaxy 1: 659 nm. Galaxy 2: 666.5 nm. Galaxy 3: 676.6 nm.

10. [4pt] Calculate the redshift, z, for each of these galaxies.

11. [4pt] Calculate the radial velocity of each of these galaxies.

12. [4pt] Assuming a Hubble Constant of 69.6 km/s/Mpc, cal- culate the distance to each of these galaxies (answer in Mpc).

Sorry you dont need to do 13 and 14

10- 12 have no graph

Answer 1

Redshift is defined as

where

is the observed wavelength and is the emitted wavelength

Galaxy 1

Galaxy 2

Galaxy 3:

The radial velocity of these galaxies are

Galaxy 1:

Galaxy 2:

Galaxy 3:

The distance to these galaxies are:

Galaxy 1:

Galaxy 2:

Galaxy 3: