Question 1

Because white dwarfs are small, as their name implies, they are hard to see. What is a way astronomers have to find white dwarfs that distinguishes them from main sequence stars?

Accepted Answer

A)  because white dwarfs get really hot, we can search for their ultraviolet radiation 
B)  because white dwarfs all have planets around them, we can use the transit method to find them 
C)  because white dwarfs are making complex molecules in their outer regions, we can search for them with radio telescopes 
D)  all white dwarfs pulsate (they get brighter and dimmer) every few minutes and this regular change in brightness is easy to notice 
E)  there is no way to distinguish white dwarfs from other dim stars. That's why we only know two or three white dwarfs in the sky.
Section 23.2: The Evolution of Massive Stars: An Explosive Finish

Question 2

Which of the following is the smallest?

Accepted Answer

A)  white dwarf 
B)  neutron star 
C)  red giant 
D)  main sequence star 
E)  protostar

Question 3

A neutron star is as dense as

Accepted Answer

A)  water 
B)  the center of the Earth 
C)  a white dwarf star 
D)  the nucleus of an atom 
E)  our astronomy textbook

Question 4

Which of the following is the largest (in diameter)?

Accepted Answer

A)  neutron star 
B)  white dwarf 
C)  red giant 
D)  main sequence star 
E)  the cloud of fossil-fuel pollution around Bayonne, New Jersey

Question 5

How did Supernova 1987A demonstrate that new elements are made in supernova explosions?

Accepted Answer

A)  spectra of the supernova light revealed elements that have never been found in Earth or the stars 
B)  the neutrinos observed from the supernova could only be produced through radioactive decay of heavy elements 
C)  a tank with 8000 tons of pure water under Lake Erie detected gamma rays from new elements 
D)  a pulsar with new elements in it was found using radio telescopes in England 
E)  the light output was kept at high levels by the energy released from radioactive elements that decay very quickly; these must have been made by the supernova

Question 6

When the BeppoSAX satellite, together with telescopes on the ground, helped astronomers pinpoint the location of the first gamma-ray burst to be identified with something that gave off visible light, the burst's location turned out to be in

Accepted Answer

A)  at the center of the Milky Way Galaxy 
B)  just behind Jupiter volcanic moon Io 
C)  in the cloud of comets at the outskirts of our solar system 
D)  in a distant galaxy 
E)  at a random spot on the sky where nothing could be seen with visible light

Question 7

Astronomers believe that the many supernova explosions that happened in the Milky Way Galaxy could have played a role in the evolution of life over billions of years. How would they have influenced the development of life on Earth?

Accepted Answer

A)  supernova explosions would have ripped continents from the crust, and caused plate tectonics 
B)  supernova explosions probably killed off many animal species on Earth with their dangerous radiation, leaving the planet for humans to dominate 
C)  the cosmic rays produced by supernova explosions would have contributed to the rate of mutations over many generations 
D)  supernova explosions would have destroyed most of the planets in the Galaxy, tearing them apart, leaving the only the Earth to give rise to life 
E)  actually, astronomers know that supernova explosions can only affect the star system in which they happen; they have no effect on the rest of the Galaxy

Question 8

Elements heavier than iron can be created during:

Accepted Answer

A)  the big bang 
B)  the main sequence 
C)  a supernova explosion 
D)  the red giant stage in a star's life 
E)  astronomers don't have any idea of where these elements came from; it's an unsolved mystery
Section 23.3: Supernova Observations

Exam 23: The Death of Stars