7. Why is there a lower mass limit for Main Sequence stars?
a. stars below a certain mass don't have enough starting mass to cause
the collapse of their parent cloud
b. stars below a certain mass have strong winds, and blow themselves apart
c. stars below a certain mass don't have cores hot enough to fuse hydrogen
d. stars below a certain mass become degenerate and explode
8. What is a brown dwarf?
a. a planet the size of Jupiter
b. a white dwarf that has stopped shining
c. an object that formed like a star, but is too small to fuse hydrogen
d. a Main Sequence star much smaller than the sun
9. The sites of current massive-star formation are marked by _______________.
a. large clusters of red giants
b. ultraviolet radiation
c. neutrino emission
d. bursts of gamma rays
10. Why is dust so important in star formation?
a. it shields gas clouds from outside radiation, allowing them to cool to
the point where they can collapse to form protostars
b. dust particles collide and stick together, and eventually these
collections of dust become massive enough to fuse hydrogen
c. the heat generated by the collision of dust particles in a star
provides the initial energy needed to start hydrogen fusion
d. the dust's self-gravity holds clouds together until they can form
stars
11. Where in the galaxy are stars being formed?
a. only in the galactic center
b. in the spiral arms
c. everywhere in the galactic disk except in the spiral arms
d. in the galactic halo
12. Where do planets form?
a. in disks around low-mass stars
b. in planetary nebulae
c. in the molecular outflow from low-mass stars
d. in ionized regions around high-mass stars