Exam 10: Galaxies

What property of a galaxy do you need to measure before you can determine its size or luminosity?

Cepheid variable stars are more luminous than the Sun.

If you wanted to measure the distance to a galaxy,what kind of objects within it could you observe?

The high ____________________ of quasars reveals to astronomers that they must be very distant.

Explain why good distance indicators must be luminous objects.Why must they be unambiguously recognizable?

Elliptical galaxies are primarily made up of massive O and B stars.

Measuring the Doppler shift of material at various distances from the centre of a galaxy can be used to construct a(n)____________________ for that galaxy.

The spectrum of a(n)____________________ consists of a continuum and a few highly redshifted emission lines due to hydrogen.

What is the major observational difference between a Seyfert galaxy and a normal spiral galaxy?

What is the Hubble constant essentially a measure of?

Based on statistical studies,what is the most common type of galaxy in the universe expected to be?

Quasar redshifts are usually larger than the redshifts of the visible galaxies.

If Galaxy A is found to have a recessional velocity four times greater than that of Galaxy B,what can you say about their relative distances from Earth?

A(n)____________________ is observed if our line of sight is along the rotation axis of an active galactic nucleus.

Which of the following generally contain well over 1000 galaxies (mainly ellipticals)packed closely together?

If a disk galaxy is reasonably close and edge-on,the Doppler shift of the galaxy disk material relative to the centre can be measured at several distances from the galaxy's centre.What does this measurement tell us about the galaxy?

What process is most likely to turn a dormant black hole at the centre of a galaxy into an active galactic nucleus?

Which of the following is the best example of a selection effect?

Describe how the effect of gravitational lensing can produce multiple images of the same quasar.

The rapid fluctuations of quasars show that the energy-emitting portions of these objects must be very small.