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Brock University
Number of pages: 9
Number of Students: 500
Number of hours: 50 min
Instructor: B.Mitrović
Test 2, June 2014
Course: ASTR 1P01
Date of Examination: June 9, 2014
Time of Examination: 14:00–14:50
1. Star Betelgeuse in Orion is 120,000 times more luminous than the Sun, yet its surface
temperature is about half of that of the Sun. This implies that
(a) the Sun’s radius is much larger than the radius of Betelgeuse.
(b) the Sun’s radius is much smaller than the radius of Betelgeuse.
(c) radii are the same.
(d) [No comparison of their radii can be made.]
2. Which of these subatomic particles has the smallest mass?
(a) Electron.
(b) Proton.
(c) Neutron.
3. Which of these forces binds electrons to the nucleus?
(a) Gravitational.
(b) Electrical.
(c) Strong nuclear.
(d) Weak nuclear.
4. Which of these forces binds together the protons and the neutrons in a nucleus?
(a) Gravitational.
(b) Electrical.
(c) Strong nuclear.
(d) Weak nuclear.
5. A photon can be absorbed by an atom only if the photon energy is equal to the energy
difference of two atomic energy levels.
(a) True.
(b) False.
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6. The chemical element helium was first detected
(a) on the Earth.
(b) in the spectrum of the Sun.
7. Which of the following stars has the hottest surface?
(a) K.
(b) G.
(c) B.
(d) F.
8. The spectral lines of an approaching star are
(a) broadened.
(b) narrowed.
(c) blueshifted.
(d) redshifted.
9. The center of mass in a binary system is closer to
(a) the more massive of the two stars.
(b) less massive of the two stars.
For Questions 10-18 and Question 46 refer to Figure 1.
Figure 1
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10. The Sun is represented in the diagram by
(a) S3 .
(b) S4 .
(c) S5 .
(d) S6 .
11. Among the main sequence stars, the one that is expected to live for the shortest period
of time is
(a) S1 .
(b) S3 .
(c) S6 .
(d) S7 .
12. Which of the following stars is a red giant?
(a) S1 .
(b) S3 .
(c) S6 .
(d) S7 .
13. Stars S6 and S7 have the same temperature, but star S6 is less luminous than star S7
because
(a) it has a larger radius.
(b) it has a smaller radius.
(c) it is a main sequence star.
(d) it is closer.
14. Comparing stars S3 and S4 , which one is expected to live longer?
(a) S3 .
(b) S4 .
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15. Which of the following stars is a white dwarf?
(a) S3 .
(b) S6 .
(c) S7 .
(d) [None of the above.]
16. Comparing stars S3 and S7 , which one has the larger radius?
(a) S3 .
(b) S7 .
17. Which of the following stars is a main sequence star?
(a) S1 .
(b) S2 .
(c) S3 .
(d) S7 .
18. Which of the following stars has the largest mass?
(a) S3
(b) S4
(c) S5
(d) S6
19. Stars on the main sequence that have a small mass are
(a) dim and hot.
(b) dim and cool.
(c) bright and cool.
(d) bright and hot.
20. A star’s distance can be determined using its spectral class and its luminosity class.
(a) True.
(b) False.
21. White dwarfs have much higher densities than the main sequence stars.
(a) True.
(b) False.
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22. A star that is cool and very luminous must have
(a) a very great distance.
(b) a very large radius.
(c) a very small mass.
(d) a very small radius.
23. Stars with masses in excess of 50 solar masses are very common.
(a) True.
(b) False.
24. The spectroscopic binaries are detected
(a) as separate stars in telescopic view.
(b) using spectroscopic parallax.
(c) based on oscillating Doppler shifts of their spectral lines.
(d) [None of the above.]
25. Typical sizes of main sequence stars (in units of solar radius R⊙ ) are
(a) from 0.01 to 0.1 R⊙ .
(b) from 0.1 to 10 R⊙ .
(c) from 100 R⊙ to 1000 R⊙ .
26. When a star’s light passes through its cooler atmosphere
(a) it is redshifted.
(b) new spectral lines appear in the spectrum.
(c) it is blueshifted.
(d) photons of certain wavelengths are absorbed.
27. To determine a star’s radius, we need its
(a) distance and mass.
(b) temperature and luminosity.
(c) distance and luminosity.
(d) [None of the above.]
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28. The combination of hydrogen and helium make up about 98% of all the mass of the Sun.
(a) True.
(b) False.
29. Which of the following is the thinnest layer of the Sun?
(a) Corona.
(b) Chromosphere.
(c) Photosphere.
(d) Radiative layer.
(e) Convection layer.
30. The Sun’s outer atmosphere is called
(a) ionosphere.
(b) photosphere.
(c) corona.
(d) chromosphere.
31. The diameter of the Sun is about
times the Earth’s diameter.
(a) 1,000,000
(b) 1,000
(c) 100
(d) 10
32. The Sun’s mass is about
times larger than the Earth’s mass.
(a) 30
(b) 300
(c) 3,000
(d) 300,000
33. The Sun’s lower atmosphere is called
(a) corona.
(b) chromosphere.
(c) ionosphere.
(d) photosphere.
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34. The layer of the Sun that we normally see is the
(a) ionosphere.
(b) photosphere.
(c) corona.
(d) chromosphere.
35. The surface temperature of the Sun in degrees Kelvin is about
(a) 6,000,000.
(b) 60,000.
(c) 6000.
(d) 600.
36. The nuclear fusion of hydrogen into helium inside a star begins at a temperature of
(a) about a million degrees.
(b) at least 10 million degrees.
(c) at least 10 billion degrees.
(d) at least 10 trillion degrees.
37. What is the first step in the proton-proton chain?
(a) Fusion of two 3 He nuclei into a 4 He nucleus.
(b) Fusion of hydrogen and deuterium into 3 He.
(c) Fusion of two protons into deuterium with a release of a positron, a neutrino and
energy.
(d) [None of the above.]
38. When four hydrogen nuclei fuse to form a helium nucleus, the total mass at the end is
the total mass at the beginning.
(a) more than
(b) the same as
(c) less than
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39. Neutrinos produced in nuclear processes in the Sun take millions of years to reach the
photosphere.
(a) True.
(b) False.
40. The Sun is supported against the crushing force of its own gravity by
(a) its rapid rotation.
(b) gas pressure.
(c) pressure created by escaping neutrinos.
(d) magnetic forces.
41. The energy is transported from the Sun’s core to its surface via
(a) conduction and convection.
(b) radiation and convection.
(c) radiation and conduction.
42. The wavelength of photons produced in the fusion core
surface.
as they move to the
(a) increases
(b) decreases
(c) stays the same
43. Granulation of the Sun’s surface is a direct consequence of
(a) heat conduction.
(b) convection.
(c) random walk of photons.
(d) heat radiation.
44. The Sun is continuously losing mass as a result of nuclear fusion reactions.
(a) True.
(b) False.
45. The neutrinos produced in proton-proton chain carry no energy.
(a) True.
(b) False.
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46. The main sequence star with the smallest mass is
(a) S1 .
(b) S3 .
(c) S6 .
(d) S7 .
47. The electron neutrino (νe ) produced in hydrogen fusion in the core of the Sun can
transform into the muon neutrino (νµ ) or tau neutrino (ντ ) as it travels through
(a) the Sun’s interior with a high electron density.
(b) the free space between the Sun and the Earth.
(c) the Earth’s crust on its way to detectors set up in mines.
48. While the Sun is a main sequence star it maintains the state of hydrostatic equilibrium
via the pressure-temperature thermostat.
(a) True.
(b) False.
49. Aurorae on Earth are caused by
(a) UV radiation.
(b) X-rays
(c) solar neutrinos.
(d) solar wind.
50. A comet’s tail points
the Sun.
(a) away from
(b) toward
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