WSU ASTR 135 Exam 2
3-25-99
Form A
1. When you observe Sun in the sky with your eyes, you are looking at thea. corona
b. chromosphere
c. photosphere
d. spicules
2. The Sun is composed mostly of:
a. water
b. oxygen
c. nitrogen
d. hydrogen
3. The granulated appearance of the Sun is evidence for
a. aurora
b. dynamo effect
c. convection
d. flares
4. The behavior of a degenerate gas is
a. no expansion with increasing temperature.
b. contraction with increasing temperature.
c. expansion with increasing temperature.
d. increase in pressure with time.
5. A star lasts the longest as a
a. protostar
b. supernova
c. red giant
d. main-sequence star
6. Just before a star explodes as a supernova, its core has turned into:
a. carbon
b. water
c. iron
d. helium
7. For main sequence stars, the general rule is: the higher the surface temperature,
a. the more numerous are the stars
b. the greater the masses of the stars
c. the less luminous are the stars
d. the more common are binary stars
8. What two properties are used to classify a star?
a. Luminosity and surface temperature
b. Distance and luminosity
c. Distance and surface temperature
d. Distance and color
9. By what mechanism does radiation reach the Sun's surface from its interior?
a. ionization
b. neutrons
c. convection
d. solar wind
10. The more massive a main-sequence star:
a. the hotter its surface temperature
b. the hotter its core temperature
c. the more rapidly the star evolves
d. all of the above
e. none of the above
11. The majority of stars in our galaxy are:
a. main sequence
b. red giants
c. white giants
d. horizontal branch stars
12. The luminosity of a star is:
a. the apparent brightness.
b. the amount of energy radiated by the star per second.
c. the amount of energy absorbed by the star.
d.
13. White dwarfs are hotter than the Sun and:
a. brighter.
b. have a larger radius.
c. dimmer.
d. have twice the mass.
14. What characteristic of the stars in a binary system can be determined by knowing the orbital period and the distance between them?
a. Absolute magnitudes
b. Stellar diameters
c. Surface temperatures
d. The combined mass
15. Compared to the Sun, giant stars:
a. are less dense.
b. are more dense.
c. have a much higher surface temperature.
d. have about the same diameter.
16. In which of the following situations is the Doppler effect NOT useful?
a. Measuring the orbital periods of binary stars.
b. Determining a star's radial motion relative to Earth
c. Determining a star's motion across the sky (proper motion).
d. Detecting spectroscopic binary stars.
17. Evidence that sunspots are sites of intense magnetic fields:
a. evidence of the Zeeman effect in spectra of sunspot regions
b. the dynamo effect
c. the Maunder butterfly diagram
d. none of the above. Sunspots are holes in the chromosphere, not sites of magnetic fields
18. The Babcock model explains the solar magnetic cycle as due to
a. bursts of solar wind particles produced by solar flares
b. helioseismology
c. the differential rotation and magnetic field of the Sun
d. coronal holes
19. As a protostar collapses in the process of becoming a star, its internal temperature increases due to
a. gravitational energy converted to thermal energy
b. nuclear fusion
c. atoms colliding with one another and breaking apart (nuclear fission)
d. the CNO cycle
20. What effect does dust have on visible light passing through it?
a. It dims and reddens it.
b. It completely blocks all visible light from passing through.
c. All light is turned a bluish color.
d. It has no effect on light.
21. For gravity to contract a spinning interstellar cloud, there needs to be sufficient
a. heat
b. mass
c. magnetism
d. rotation
22. What defines a main-sequence star?
a. rapid rotation and strong stellar winds
b. fusion of hydrogen into helium in the core
c. the surface temperature
d. the apparent brightness
23. The proton-proton chain needs a temperature of
a. 10 K
b. 100 K
c. 10,000 K
d. 107 K
24. In the proton-proton chain releases energy because
a. energy is converted into mass.
b. mass is converted into energy.
c. chemical bonds are broken.
d. chemical bonds are formed.
25. T Tauri stars are examples of
a. protostars
b. supergiants
c. white dwarfs
d. main-sequence stars
26. For stars that are not expanding or contracting, the inward force of gravity is counteracted by
a. neutrinos moving outward.
b. tidal forces from planets.
c. internal gas pressure.
d. anti-gravity.
27. The escape velocity at the event horizon of a black hole is
a. 100 m/sec
b. 1000 m/sec
c. the speed of light
d. twice the speed of light
28. The Schwarzschild radius is associated with
a. the maximum size possible for a white dwarf star
b. the size of the cone of radiation emitted by pulsars
c. a nebula whose size allows it to eventually collapse to become a star
d. the size of the event horizon of a black hole
29. What compelling evidence links pulsars to neutron stars?
a. Both are found in globular clusters.
b. A small object like a neutron star could emit short precisely time pulses, and many pulsars are found in supernova remnants.
c. Both have been discovered near the Sun.
d. Pulsar emit beams of neutrons.
30. The higher the mass of a main-sequence star
a. the faster hydrogen in the core is converted to helium.
b. the longer it will remain on the main-sequence.
c. the slower hydrogen in the core is converted to helium.
d. the lower the luminosity.
31. Why are star clusters good for stellar evolution studies?
a. The combined light of the stars makes them easier to see.
b. Star clusters are always located in the plane of the galaxy.
c. Stars in clusters began forming at the same time, have similar starting composition, and are at about the same distance away.
d. Stars in clusters are always very young and shine brightly.
32. What is the single most important characteristic in determining the course of a star's evolution?
a. apparent brightness
b. distance
c. color
d. mass
33. What is the barrier making it difficult for two protons to stick together?
a. antigravity
b. electric repulsion
c. no barrier exists
d. strong force
34. The interstellar gas is composed mainly of:
a. hydrogen and helium
b. carbon
c. ammonia, methane, and water
d. iron
35. All stars must eventually leave the main-sequence because
a. they deplete the hydrogen in their cores.
b. they use up the helium in their cores.
c. they use up the iron in their cores.
d. gravity weakens over time.
36. The evolution of binary stars can be complex
a. if they are close enough to exchange mass.
b. since they are moving around a center of mass.
c. because tidal forces cause fusion to proceed faster.
d. because they can eclipse.
37. What is it that prevents some stars from collapsing past the white dwarf stage?
a. Neutrinos emitted by the explosion that creates the white dwarf push outward
b. Degenerate electrons resist further compression
c. The helium flash pushes the star outward
d. The carbon detonation event pushes the star outward
38. If the mass of a white dwarf exceeds 1.4 time the mass of the Sun by infalling material from a binary companion star the result will be a
a. nova
b. type-I supernova
c. type-II supernova
d. contact binary
39. If two observations of the stars Alpha Centauri and Arcturus are made at 6 month intervals, Alpha Centauri reveals a greater parallax because it is
a. closer to us than Arcturus
b. hotter than Arcturus
c. more massive than Arcturus
d. more distant than Arcturus.
40. The temperatures of any star can be measured from its:
a. magnitude
b. magnetic field
c. spectra
d. distance
41. Apparent magnitude depends on
a. H-R diagram and temperature
b. luminosity and distance
c. giant stars and white dwarfs
d. visual and spectroscopic binaries
42. An iron core cannot support a star because:
a. iron rusts
b. iron cannot fuse with other nuclei to produce energy
c. iron supplies too much pressure
d. iron is too heavy
43. A star can be a supernova
a. many times
b. at various times, depending on the mass
c. once
d. just twice
44. If a stellar core is not producing energy via nuclear fusion
a. it will contract and heat up.
b. it will heat up and expand.
c. it will expand and cool.
d. it will contract and cool.
45. Black holes are most easily identified
a. when their effect on a nearby star can be observed
b. by looking for locations in the sky where it is particularly dark
c. with the largest optical telescopes on Earth
d. when Earth is lined up along the magnetic axis of the black hole
46. Until very recently, what about the Sun's corona was poorly understood?
a. Why that part does not drift away from the Sun.
b. Why during a solar eclipse it disappears.
c. Why it is a million times denser than the photosphere.
d. Why it is much hotter than the other layers of the Sun's atmosphere.
47. The average density of the Sun is closest to:
a. iron
b. the Earth
c. white dwarf
d. water
48. The Sun's polar regions rotate:
a. faster than the equatorial regions.
b. slower than the equatorial regions.
c. at the same speed as the equatorial regions.
d. in the opposite direction to the Sun's equator.
49. In order to know for certain that an object is a black hole, astronomers must first
a. observe a circular black disc in the sky
b. detect pulses of radiation coming from the event horizon. This is called the lighthouse effect
c. detect glitches in the radiation emitted by the black hole
d. determine the mass of the compact object suspected of being the black hole
50. A neutron star has a size of about
a. 10 cm
b. 20 km
c. 6000 km
d. 1 AU