The traditional top-down hypothesis of the formation of our galaxy cannot explain
a. why not all globular clusters are the same age.
b. why the youngest globular clusters are in the outer halo.
c. why the oldest stars are metal poor but not completely metal free.
d. streams and rings of scattered stars in the halo.
e. All of the other choices are correct.
Question 2Emission nebulae are also called ________ because they are composed of ionized hydrogen.
a. HI regions
b. HII regions
c. Bok globules
d. HeI regions
e. reflection nebulae
Question 3The traditional top-down hypothesis states that the galaxy formed
a. from a large spherical cloud of gas that was rotating very slowly.
b. from a large cloud of material that broke off a larger galaxy.
c. from material that had been ejected in the violent explosion of a dying galaxy.
d. as a result of mergers between several smaller groups of gas, dust, and stars.
e. as two massive galaxies collided.
Question 4The visual pink glow of the Great Nebula in Orion
a. is a Herbig-Haro object.
b. is a reflection nebula of dust.
c. is an emission nebula of thin gas.
d. contains only young low mass stars.
e. is believed to be about 5 billion years old.
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