Exam 10: Galaxies

Why should we expect quasars to be small? How small should we expect them to be?

How do astronomers know that there is activity in the nuclei of some galaxies?

What distance method is used to calibrate galaxy distances?

Which of the following best describes poor clusters?

Describe a model of a quasar and show how the model explains the observed properties of a quasar.

What information about a cluster of galaxies can lensing of background galaxies by the cluster be used to determine?

What type of galaxies do astronomers believe are the most common?

Which of the following sequences sorts the galaxy types according to the rate at which new stars are forming,from highest rate to lowest rate?

____________________ clusters of galaxies contain closely spaced galaxies,and often contain giant elliptical galaxies and a hot intergalactic medium.

Which of the following are produced when two galaxies pass near each other and pull large streamers of stars,gas,and dust away from each other?

What produces the energy from an active galactic nucleus?

If a galaxy has a radial velocity of 8000 km/sec and the Hubble constant is 70 km/sec/Mpc,what is the distance to this galaxy?

What distance method is used to determine the distance to the most distant galaxies?

What assumptions do we make when we use the Hubble constant to estimate the distance to a galaxy?

What type of galaxy has an elongated nucleus with a spiral structure extending from the ends of the elongations?

Elliptical galaxies contain more gas,dust,and young stars than Sa galaxies.

What evidence do we have that large galaxies cannibalize small galaxies?

The units of the Hubble constant are ____________________.

What is look-back time?

What can the rotation curve of a galaxy be used to determine?