12. After all its fuel has been exhausted, the sun will end up as:
a. a white dwarf with a mass less than 1 solar mass
b. a nova, with a 1 solar mass white dwarf as the remnant
c. a supernova, with a neutron star remnant
d. a black hole
13. What happens when the mass of a white dwarf exceeds the Chandrasekhar
limit?
a. it begins steady carbon fusion in its core
b. it collapses into a black hole
c. it goes supernova
d. it becomes a Cepheid
14. What is a pulsar?
a. a variable star whose period and luminosity are related
b. a burst of gamma rays from a neutron star
c. the rapidly-spinning neutron core left over after a supernova
d. a signal from extraterrestrial intelligent life
15. Neutron stars can spin:
a. up to about 1/2 the frequency of the sun, about once every 50 days
b. up to the frequency of the sun, about once every 20 days
c. up to 15,000 times the frequency of the sun, about once a minute
d. up to a billion times the frequency of the sun, about once a millisecond
(10-3 second)
16. A black hole is
a) An object so massive that light can not escape from its surface
b) An object so small that light can not escape from its surface
c) An object whose escape velocity exceeds the speed of light
d) Any massive celestial object that does not emit light
17. If the period of a Cepheid is measured, its ____________ can be
determined, from which its ____________ can be calculated.
a. color; age
b. luminosity; distance
c. brightness; mass
d. spectral type; radius