D.3 Expanding Universe questions
z = Δλ/λ = v/c = R/R
0
– 1
v = H
0
d
1. Galaxy NGC 123 has a velocity away from us of 1,320 km/s and the Hubble
Constant's value is 70 km/s/Mpc. How far away is the galaxy according to
Hubble's Law?
2. Galaxy NGC 2342 has a velocity of 5,690 km/s and is at a distance of 74
Mpc away. What is the value of the Hubble constant based upon these values?
3. Galaxy NGC 4442 is 120 Mpc away. If the Hubble Constant is 68 km/s/Mpc,
how fast should NGC 4442 be moving due to the expansion of the Universe?
4. An absorption line of calcium usually has a wavelength of 3.934 x 10
-7
m, but
it is observed in a galaxy to have a wavelength of 4.002 x 10
-7
m. How fast is
this galaxy moving, and is it moving towards or away from you?
5. An absorption line of sodium usually has a wavelength of 588.995 nm, but it
is observed in a galaxy to have a wavelength of 600.023 nm. What is the
redshift ratio?
6. An absorption feature of calcium usually has a wavelength of 393.4 nm, but it
is observed in a distant galaxy to have a wavelength of 820.9 nm. What is the
redshift?
