How is the age of the galaxy determined?
a. measuring the metallicity of Population II stars
b. finding the turnoff point in the H-R diagram of globular clusters
c. from the motion of stars in the galactic halo
d. counting the number of open clusters in the spiral arms
Question 2The free-fall contraction of a molecular cloud
a. can be initiated by shock waves from supernovae.
b. can be initiated by nearby spectral type G stars.
c. can be initiated by the rotation of the cloud.
d. causes the cloud to become transparent to ultraviolet radiation.
e. causes the particles in the cloud to decrease the speed with which they move.
Question 3How did Harlow Shapley use the period-luminosity relationship of RR Lyrae variables to determine the size of the Milky Way galaxy?
a. He determined the proper motion of globular clusters in the outer disk of the galaxy.
b. He found the distances to individual variables free floating in the halo.
c. He found the distances to open clusters found throughout the disk of the galaxy.
d. He found the distances to globular clusters distributed about the center of the galaxy.
Question 4What causes the outward gas pressure that balances the inward pull of gravity in a main-sequence star?
a. the rapid outward flow of gas
b. the rapid inward flow of the gas
c. the high temperature of the gas
d. the high density of the gas
e. the high temperature and the high density of the gas
Question 5What behavior do galactic rotation curves exhibit to suggest the existence of dark matter in an extended halo?
a. Small velocities are seen at large distances from the galactic center.
b. Small velocities are seen at distances close to the galactic center.
c. Large velocities are seen at large distances from the galactic center.
d. Large velocities are seen at distances close to the galactic center.
Question 6The carbon-nitrogen-oxygen cycle
a. operates at a slightly lower temperature than the proton-proton chain.
b. is most efficient in star less massive than the Sun.
c. occurs when carbon and oxygen combine to form nitrogen, which produces energy.
d. produces the energy responsible for bipolar flows.
e. combines four hydrogen nuclei to form one helium nucleus, which produces energy.
Question 7How did Harlow Shapley determine where the center of the galaxy lies?
a. He plotted the distribution of open clusters.
b. He plotted the distribution of globular clusters.
c. He made star counts in every direction of the galactic disk.
d. He measured the amount of dust obscuration in every direction of the galactic disk.
Quick Reply
