Sample questions for the third exam
1. Compare two white dwarf stars, X and Y. X has a mass of 0.6 solar masses. Y has a mass of 1.2 solar masses.
a. X is bigger in diameter than Y
b. X is smaller in diameter than Y
c. X will explode as a type II supernova
d. Y will explode as a type II supernova
2. A star is found with a parallax of 0.2 seconds of arc. How far away is the star?
a. 0.2 parsecs
b. 5 light years
c. 2 light years
d. 5 parsecs
3. Stars at the top end of the main sequence have shorter lives than those at the bottom end because
a. they have smaller masses and fainter luminosities
b. they have cooler surface temperatures
c. they have higher masses but much higher luminosities
d. they have helium fusing to carbon in their centers
4. The Sun is believed to be powered by
a. gravity
b. hydrogen fusing into helium
c. helium fusing into carbon
d. the triple alpha process
5. If four hydrogen atoms had a lower mass than one helium atom, then
a. the Sun could not shine by fusing hydrogen to helium
b. we would lose energy if we broke up a helium atom into four protons
c. the Sun would have a longer main sequence life than is actually the case
d. the Sun would be a star at the top of the main sequence
6. Sunspots
a. come and go in an 11 year cycle
b. are hotter than the surrounding photosphere
c. showed that the Sun does not rotate on its axis
d. radiate no energy into space
7. Energy created in the center of the Sun moves outward
a. first by convection, then by conduction
b. first by conduction, then by convection
c. first by radiation, then by convection
d. first by convection, then by radiation
8. During the Maunder minimum
a. something caused the Sun to spin very slowly on its axis
b. the Sun produced very few neutrinos
c. the Sun produced an unusually large number of neutrinos
d. the Sun had very few sunspots
9. The Sun can shine on the main sequence for a total of about
a. 100 million years
b. 1 billion years
c. 10 billion years
d. 100 billion years
10. Which has the longest main sequence lifetime?
a. an O type main sequence star
b. an M type main sequence star
c. a G type main sequence star
d. an A type main sequence star
11. Consider stars X and Y. X has a spectral type of M. Y has a spectral type of A. The luminosity of X is 100 solar luminosities. The luminosity of Y is also 100 solar luminosities.
a. Y must be older than X
b. Y must be bigger in diameter than X
c. X must be bigger in diameter than Y
d. X must be more massive than Y
12. All main sequence stars
a. are powered by hydrogen fusing to helium
b. have iron cores
c. are 98 % hydrogen by mass
d. are younger than the Sun
13. Consider star clusters X and Y. Cluster X has main sequence turnoff stars of spectral type G. Cluster Y has main sequence turnoff stars of spectral type A.
a. Both X and Y must be globular clusters
b.Cluster X is older than cluster Y
c. Cluster Y must contain at least one main sequence star of spectral type B
d. Cluster Y must contain at least one blue supergiant star
14. Protostars are powered by
a. hydrogen fusing to helium
b. gravity
c. the triple alpha process
d. uranium fission
15. As a fragment of a giant molecular cloud collapses it
a. cools and radiates mainly in the ultraviolet
b. heats and spins more slowly
c. heats and radiates mainly in the infrared
d. forms a disk made mainly of heavy elements
16. In the HR diagram, you find protostars
a. below the main sequence
b. in the white dwarf region
c. on the main sequence
d. above the main sequence
17. The Sun is expected to become
a. a red giant
b. a white dwarf
c. a planetary nebula
d. all of the above
18. A massive star is ready to become a supernova when
a. all of its central helium has been fused into hydrogen
b. it reaches the top of the main sequence
c. its core has become iron
d. it becomes a pulsar
19. A protostar with a mass of 0.06 solar masses
a. will become a brown dwarf
b. will be above the Sun on the main sequence
c. will fuse hydrogen to helium when its core reaches 10 million degrees
d. will fragment into smaller pieces
20. Which of the following is likely to have been created in a supernova explosion?
a. the hydrogen in ocean water
b. the helium in a balloon
c. the uranium in a nuclear reactor
d. the carbon in your body
21. A pulsar is believed to be
a. a supermassive white dwarf
b. a black hole
c. a gamma ray burster
d. a neutron star
22. ______________ can escape from inside the event horizon of a black hole.
a. gamma rays
b. X rays
c. neutrinos
d. nothing that we know of
23. Rapidly moving stars near the center of the Milky Way indicate that
a. it has been the site of many supernova explosions
b. it contains a black hole
c. it is a quasar
d. it is the oldest part of the Milky Way
24. Stars in the disk of the Galaxy
a. revolve in very eccentric (non-circular) orbits
b. typically have fewer heavy elements than the Sun
c. are mostly very old stars
d. move in the same direction when orbiting the Galactic center
25. Stars in the halo of the Galaxy
a. are very old
b. are mostly bluer than the Sun
c. are mostly more massive than the Sun
d. usually have circular orbits
26. Where would you look to find O and B main sequence stars?
a. the bulge
b. the halo
c. spiral arms
d. globular clusters
27. Most of the interstellar gas and dust in the Milky Way is located
a. in the halo
b. in the disk
c. in Sgr A*
d. in the bulge
28. Suppose the Sun were replaced by a one solar mass black hole. The Earth would
a. move farther away from the black hole
b. fall towards the black hole
c. keep in its current orbit
d. move at a higher rate of speed than it does now
29. The Milky Way galaxy
a. is younger than the Sun
b. is about 100,000 light years across
c. contains no known brown dwarfs
d. is shaped like an oval
30. When electrons are squeezed tightly together they
a. emit a burst of gamma ray light
b. become degenerate and strongly resist being pushed further together
c. combine to form neutrons
d. fuse to make carbon
31. If the core of a collapsing star has a mass smaller than 1.4 solar masses, it is likely to become
a.. a white dwarf
b. a neutron star
c. a brown dwarf
d. a type II supernova
32. The Sun is
a. one of the oldest stars in the Milky Way
b. one of the youngest stars in the Milky Way
c. about 28,000 light years away from the center of the Milky Way
d. within 600 light years of the center of the Milky Way
33. Asteorid X is 4 AU from the Sun. Asteroid Y is 8 AU from the Sun. Asteroid X gets
a. four times as much solar energy per second per square meter as asteroid Y
b. twice as much solar energy per second per square meter as asteroid Y
c. sixteen times as much solar energy per second per square as asteroid Y
d. gets just as much solar energy per second per square meter as asteroid Y
34. The spectral type of a star tells you its
a. mass
b. luminosity
c. surface temperature
d. all of the above
35. The granules on the Sun are believed to be
a. small sunspots
b. areas of especially low temperature
c. the hottest parts of the corona
d. the tops of convection cells
1. a 2. d 3. c 4. b 5. a 6. a 7c 8 d 9. c 10. b 11. c 12. a 13. b 14. b 15. c 16. d 17. d 18. c 19. a 20 c 21. d 22. d 23. b 24. d 25. a 26. c 27. b 28. c 29. b 30. b 31. a 32. c 33. a 34. c 35. d