Astronomy

# Figuring for Yourself

AstronomyFiguring for Yourself

### Figuring for Yourself

27.

According to Hubble’s law, what is the recessional velocity of a galaxy that is 108 light-years away from us? (Assume a Hubble constant of 22 km/s per million light-years.)

28.

A cluster of galaxies is observed to have a recessional velocity of 60,000 km/s. Find the distance to the cluster. (Assume a Hubble constant of 22 km/s per million light-years.)

29.

Suppose we could measure the distance to a galaxy using one of the distance techniques listed in Table 26.2 and it turns out to be 200 million light-years. The galaxy’s redshift tells us its recessional velocity is 5000 km/s. What is the Hubble constant?

30.

Calculate the mass-to-light ratio for a globular cluster with a luminosity of 106 LSun and 105 stars. (Assume that the average mass of a star in such a cluster is 1 MSun.)

31.

Calculate the mass-to-light ratio for a luminous star of 100 MSun having the luminosity of 106 LSun.