SAMPLE
EXAM 3: FOR STELLAR
EVOLUTION
1. The masses of stars on the main sequence __________ from the
lower right to the upper left.
a. increase
b. decrease
c. are all the same
d. are randomly distributed
2. The fundamental quantity which determines a star's central
pressure and temperature is its
a. mass.
b. luminosity.
c. surface temperature.
d.
chemical
e. radius.
3.
The Russell-Vogt theorem (about
chemical
at any given age depend
a. luminosity and radius.
b. mass and luminosity.
c. mass,
chemical
d. radius, and
chemical
e. mass and chemical
4. The lifetime of a star is determined by its initial
a. temperature and luminosity.
b. temperature and radius.
c. temperature and mass.
d. mass and luminosity.
e. mass and radius.
5. Stars evolve because of changes in
a. chemical
b. luminosity of the star.
c. mass of the star.
d. chemical
e. surface temperature.
6. The triple alpha reaction converts _________ into __________.
a. hydrogen, helium
b. helium, hydrogen
c. helium, carbon
d. carbon, nitrogen
e. hydrogen, nitrogen
7. A nuclear reaction which occurs at sometime after hydrogen is
exhausted in the core is the
a. CNO cycle.
b. triple alpha reaction.
c. helium-iron chain.
d. electron-positron cycle.
e. tritium-alpha cycle.
8. The temperature of a star's core will __________ as the star
fuses heavier elements.
a. increase
b. decrease
c. remain the same
9. Which one of the following is NOT a class of star cluster?
a. galactic clusters
b. open clusters
c. closed clusters
d. globular clusters
e. stellar associations
10. Which of the following is NOT an assumption made in the study
of star clusters?
a. all the stars are at the same distance
b. all the stars formed at the same time
c. all the stars have the same chemical
d. all the stars have the same mass
11. Which of the following can NOT be obtained from a
color-magnitude diagram?
a. a cluster's age
b. a cluster's distance
c. the relative brightnesses of stars in a cluster
d. the cluster velocity
12. ____________________________________________
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What would be the correct order of the clusters shown above,
if they are arranged from youngest to oldest?
a. ABC
b. ACB
c. BAC
d. BCA
e. CAB
f. CBA
13. The evolution of a star depends primarily on the star's
a. radius.
b. mass.
c. luminosity.
d. density.
e. temperature.
14. Stars on the upper end of the main sequence next evolve into
a. red dwarfs.
b. lower main sequence stars.
c. solar-type stars.
d. white dwarfs.
e. red giants.
15. The main sequence turn-off is useful in determining a
cluster's
a. mass.
b. age.
c. distance.
d. apparent magnitude.
e. velocity.
16. The H-R diagram for cluster A consists of stars on the main
sequence, while the diagram for cluster B has stars both on
the main sequence and just above the main sequence at lower
temperatures. Which cluster is older?
a. cluster A
b. cluster B
c. both clusters are the same age
d. more information is required
17. A T Tauri star is one which is
a. like the Sun.
b. variable and shedding mass.
c. old and shedding mass.
d. be
e. a main sequence star.
18. Protostars in dark, dusty regions may be studied in the
__________ spectral region.
a. X-ray
b. ultraviolet
c. visual
d. infrared
e. gamma-ray
19. During the formation of a star, the contraction stops when
a. the star collapses into a black hole.
b. the star collapses into a white dwarf.
c. hydrogen burning be
d. helium burning be
e. the star be
20. Hydrogen burning for a Sun-like star lasts approximately
a. one million years.
b. ten million years.
c. one hundred million years.
d. one billion years.
e. ten billion years.
21. What types of stars are found on the zero-age main sequence
(ZAMS)?
a. red giants
b. protostar
c. newly formed stars
d. stars that have not yet started to burn hydrogen
e. white dwarfs
22. When the hydrogen in the core of a star has been converted to
helium, the core will next
a. contract.
b. expand.
c. burn helium.
d. decrease in temperature.
e. explode.
23. Which of the following occurs during and immediately after the
phase of the hydrogen burning shell?
a. the core shrinks until the star be
b. the helium flash occurs
c. the core temperature decreases while the envelope
temperature increases
d. the star be
e. the envelope expands and cools, and the
star be
giant
24. As a degenerate gas is heated, it will
a. expand.
b. contract.
c. neither expand nor contract.
d. oscillate.
25. The ignition of helium in the degenerate core of a one solar
mass star produces
a. a supernova.
b. a black hole.
c. the formation of new heavy elements.
d. a helium flash.
e. nothing much - the core expands, cools, and continues
burning.
26. In a degenerate electron gas the outward pressure which keeps
the star from collapsing is
a. dependent upon temperature.
b. dependent upon mass.
c. independent of temperature.
d. independent of mass.
27. Which of the following is NOT a characteristic of a red giant?
a. extended outer layers
b. degenerate core
c. cool core
d. cool surface temperature
28. The horizontal branch is
a. a region on the H-R diagram where stars have roughly the
same temperature.
b. a region on the H-R diagram where stars have roughly the
same luminosity.
c. seen only in young clusters where protostars are evolving
towards the main sequence.
d. the track that white dwarfs follow.
29. After a Sun-like star enters its second red giant phase, its
internal structure would consist of
a. a carbon core surrounded by a helium burning shell, which
is surrounded by a hydrogen burning shell.
b. a helium core surrounded by a hydrogen burning shell.
c. a iron core surrounded by many different layers of shell
burning.
d. a oxygen core surrounded by a carbon burning shell, a
helium burning shell, and a hydrogen burning shell.
30. A planetary nebula is
a. a collapsing gas cloud out of which planets will form.
b. an expanding gas cloud that was ejected by a star.
c. the cloud of gas blown off by a T Tauri type star.
d. a gas cloud which goes into the formation of red giants.
31. The stellar remnant of a one solar mass star is a
a. white dwarf.
b. neutron star.
c. pulsar.
d. black hole.
e. main sequence star.
32. High mass stars evolve more rapidly than low mass ones because
the high mass stars
a. are larger
b. have higher core temperatures.
c. have higher core densities.
d. are made of more massive elements.
e. are in the lower right corner of the H-R diagram.
33. In the most massive stars, the heaviest element which will be
produced in the core will be
a. helium.
b. oxygen.
c. silicon.
d. iron.
e. uranium.
34. Each time a form of nuclear fuel is exhausted in the core of a
star, the star
a. returns to the main sequence.
b. returns to the red giant branch.
c. returns to the white dwarf region.
d. explodes in a supernova explosion.
e. ejects a planetary nebula.
35. The most mass a white dwarf can have is about
a. 1 Solar Mass.
b. 1.4 Solar Mass.
c. 3 Solar Masses.
d. 10 Solar Masses.
e. there is no limit to the mass.
36. What element is observed in the spectra of Type II supernova?
a. hydrogen
b. helium
c. iron
d. uranium
37. A star which has a main sequence mass of 10 solar masses will
most likely end up as
a. a T Tauri star.
b. a white dwarf.
c. a neutron star.
d. a black hole.
38. If a neutron star has more mass than its mass limit, it will
a. expand catastrophically.
b. contract catastrophically.
c. begin a new phase of nuclear reactions.
d. nothing will happen.
39. A black hole is called that because
a. its color is black.
b. its energy output depends on its temperature.
c. photons can not be emitted from it.
d. they exist only in the dark reaches of space where there
are no stars.
40. A neutron star's size is that of
a. the Sun.
b. the Earth.
c. the Earth's orbit.
d. the State of Iowa.
e. a typical city.
41. The most massive stars are thought to end up as
a. black holes.
b. planetary nebulae.
c. neutron stars.
d. white dwarfs.
42. Heavy elements which are mixed into the material from which
new
generations
of stars may
a. the big bang.
b. planetary nebulae.
c. supernovae.
d. super-neutron stars.
e. Wolf-Rayet stars.
43. After the initial outburst of Supernova 1987A had diminished,
the main source of luminosity was energy released from
a. radioactive decay.
b. the neutron star formed during the explosion.
c. the high temperature core which remains.
d. the expanding envelope.
e. the ejection of slowing moving neutrinos.
44. What
was the most energetic
a. the visible light
b. the kinetic energy of the expanding gas cloud
c. the energy released in neutrinos
d. the X-ray energy
45. Which of the following objects would have the highest
gravitational redshift?
a. a white dwarf
b. the Sun
c. a neutron star
d. a black hole
46. A
white dwarf will cool to be
a. thousand years.
b. million years.
c. billion years.
47.
White dwarfs are
a. normal (perfect) gases.
b. degenerate gases.
c. equal amounts of normal (perfect) and degenerate gases.
d. hot, solid material.
48. All novae are thought to involve a
a. white dwarf.
b. main sequence star.
c. supergiant.
d. neutron star.
e. black hole.
49. Novae explosions are caused by
a. exploding white dwarfs.
b. interstellar matter falling onto the surface of a star,
usually a white dwarf.
c. material falling into a black hole.
d. mass lost from a normal star falling onto a white dwarf
e. strong flares on a stellar surface (large-scale "solar"
flares).
50. How can astronomers determine which type of supernovae they
are observing?
a. Type I supernovae fade much more quickly than Type II
b. the brightnesses are different
c. the spectral features are different
d. by determining exactly which object produced the supernova
51. The internal properties of a neutron star are most similar to
those of a __________ star.
a. main sequence
b. red giant
c. red dwarf
d. white dwarf
e. solar-type
f. blue supergiant
52. Stellar remnants with masses between 2 and 3 solar masses will
be
a. white dwarfs.
b. neutron stars.
c. black holes.
d. planetary nebulae.
53. Pulsars are known to be
a. pulsating white dwarfs.
b. pulsating neutron stars.
c. rotating white dwarfs.
d. rotating neutron stars.
e. rotating black holes.
54. Binary X-ray sources are known to be binary because
a. the two stars are observed visually as visual binary
stars.
b. they are astrometric binaries.
c. eclipses are observed.
d. the name is a misnomer since no X-ray objects are known to
be binary.
55. The accretion disk surrounding a neutron star is very hot due
to
the object will emit strongly in which spectral region?
a. X ray
b. ultraviolet
c. visual
d. infrared
e. radio
56. If the Sun were suddenly to be replaced by a solar-mass black
hole the gravitational force on the Earth (1 A. U. away) would
a. double.
b. be
black hole.
c. decrease because black holes cause gravity at large
distances to disappear.
d. remain the same.
57. The Schwarzschild radius of a black hole is
a. the radius of the star when it is on the main sequence.
b. the distance from a black hole inside of which light
cannot escape.
c. the theoretical size of the smallest possible white dwarf.
d. the size of a star when it begins hydrogen burning just
prior to reaching the main sequence.
e. the size of the early protosun.
58. From the outsider's point of view, in watching a star collapse
to form a black hole, the collapse would appear to take
a. only a fraction of a second.
b. a few hours.
c. forever.
59. Which of the following lists the stellar remnants in order of
decreasing maximum mass?
a. neutron star, white dwarf, black hole
b. black hole, neutron star, white dwarf
c. white dwarf, black hole, neutron star
d. black hole, white dwarf, neutron star
e. they all have approximately the same mass
60. A black hole is really
a. a star of temperature 0 K.
b. densely packed matter.
c. strongly curved space.
d. at the center of most stars and provides the star's
energy.
61. How is it possible to detect the presence of a black hole?
a. using a large optical telescope to see its surface
b. using a large radio telescope to see its surface
c. by its effect upon other objects around it
d. by watching material cross its event horizon
Answer
Key for Sample Exam 3
1. a
2. a
3. e
4. d
5. a
6. c
7. b
8. a
9. C
10. d
11. d
12. e
13. b
14. e
15. b
16. a
17. b
18. d
19. c
20. e
21. c
22. a
23. e
24. c
25. d
26. c
27. c
28. b
29. a
30. b
31. a
32. b
33. d
34. b
35. b
36. a
37. c
38. b
39. c
40. e
41. a
42. c
43. a
44. c
45. d
46. c
47. b
48. a
49. d
50. c
51. d
52. b
53.
d
54.
c
55.
a
56.
d
57.
b
58.
c
59.
b
60.
c
61.
c