The spherical component is the __________.
a. halo b. bulge
c. halo and bulge d. dark matter
Question 2Absorption lines due to the interstellar medium indicate that some components of the interstellar medium are cold and of a very low density because
a. the lines are blue shifted.
b. the lines are red shifted.
c. the lines are extremely broad.
d. the lines are extremely narrow.
e. the lines are much darker than the stellar lines.
Question 3Which pulsate faster?
a. lower mass, smaller stars b. higher mass, larger stars
c. dimmer, smaller stars d. brighter, smaller stars
Question 4________ are small dark nebulae about 1 light-year in diameter that contain 10 to 1,000 solar masses.
a. HI regions
b. HII regions
c. Emission nebulae
d. Bok globules
e. Reflection nebulae
Question 5More massive stars are _________ luminous and __________ than less massive stars, thus they pulsate _____________.
a. less, smaller, faster b. more, larger, slower
c. more, larger, slower d. less, smaller, faster
Question 6The creation of ________ require(s) that a young hot star (T 25,000 K) be relatively nearby.
a. emission nebulae
b. HI regions
c. molecular clouds
d. the cool gas of the interstellar medium
e. 21-cm radiation
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