AST 2010, Exam 2, Winter 2014Prof. Bonvicini

AST 2010: Descriptive Astronomy

EXAM 2

March 3, 2014

DO NOT open the exam until instructed to. Please read through the instructions below and fill out your details on the Scantron form.

Instructions

  1. The exam consists of 50 multiple choice questions.
  2. There will be 1 hour and 45 minutes to complete the exam.
  3. Answers are to be marked on the Scantron answer sheet provided.
  4. A list of useful equations and constants are provided. No student notes are allowed.
  5. Please answer using a No. 2 pencil only (pen will not be read by the machine).
  6. Read the instructions on the answer sheet for how to mark your answers correctly.
  7. Scientific calculators are allowed, however, cell phones are not.
  8. Use of cell phones will be considered cheating and will result in a 0.
  9. Cheating of any sort is not tolerated and will result in a 0 and potential further action.

Please now fill in your Last Name, First Name and student ID number in the relevant boxes on the Scantron form. There is no need to fill in the Birth date, Sex or Grade/Education.

Physical Constants

Name / Symbol / Value
Speed of light / c / 3 × 108 m s-1
Gravitational constant / G / 6.67 × 10-11 m3 kg-1 s-2
Planck’s constant / h / 6.63 × 10-34 J s
Stefan-Boltzmann constant / σ / 6.67 ×10-8 W m-2 K-4
Wien’s law constant / T ×λmax / 2.90 × 106 K nm

Astronomical Constants

Name / Symbol / Value
Astronomical Unit / AU / 1.50 × 1011 m
Light-year / ly / 9.46 × 1015 m = 63,240 AU
Parsec / pc / 3.09 × 1016 m = 206,265 AU = 3.26 ly
Year (synodic) / yr / 365.2422 days = 3.1557 × 107s
Mass of Earth / M / 5.97 × 1024 kg
Mass of Sun / M / 1.99 × 1030 kg
Equatorial radius of Earth / R / 6378 km
Radius of Sun / R / 6.96 × 108 m
Luminosity of Sun / L / 3.83 × 1026 W
Hubble’s constant / H0 / 72 km s-1 Mpc-1

Some useful equations

Geometry

Circumference of a circle = 2πR

Area of a circle = πR2

Surface area of a sphere = 4πR2

Volume of sphere = πR3

Distance Relationships

Distance – velocity – time: d = v × t

Linear size - angular size: l = d ×α/57.3°

Distance from parallax: d (in parsecs) = 1/p(in arcsec)

Hubble’s law (for distance galaxies): d = v/H0

Gravity

Kepler’s 3rd Law: P2 = a3 when P is in years and a is in AU

Gravitational force between two masses:

Gravitational potential energy:

Newton’s modified form of Kepler’s 3rd law: (for d in AU and P in years)

Mass of object for orbital speed v and at distance R:

Escape velocity:

Light

Frequency (ν) – wavelength (λ) relation: λ ×ν = c

Energy of a photon:

Stefan-Boltzmann law: L = σT4× (surface area)

Wien’s Law:

Brightness (B) – Luminosity (L) relation:

Doppler effect: Radial velocity = VR =

Other Physical Relationships

Density = Mass / Volume

Newton’s 2nd Law: F = m × a

Kinetic Energy: KE = ½ m × v2

Conservation of angular momentum: Mass × Circular velocity × Radius = constant

Questions

  1. The ability of a telescope to detect fine detail is called
  2. Finesse
  3. Persistence
  4. Focus
  5. Aperture
  6. Resolution
  1. The aperture of a telescope if determined by the area of its primary mirror or lens
  2. True
  3. False
  1. The device used to detect light in digital cameras is called
  2. Electron modulator
  3. Photomultiplier tube
  4. False color image
  5. CCD (or charge-coupled device)
  6. Aperture
  7. The largest telescopes are the optical telescopes
  8. True
  9. False
  10. When looking through a green ______, you see only the green light coming from each object.
  11. Aperture
  12. Coherent
  13. Filter
  14. Collecting area
  15. None of the above
  16. If the radius of a telescope’s mirror is doubled, the surface area increases by
  17. 2 times
  18. 3 times
  19. 4 times
  20. 8 times
  21. None of the above
  22. The diagram below displays an example of a
  23. Refracting telescope
  24. Newtonian telescope
  25. Cassegrain telescope
  26. Copernican telescope
  27. None of the above

  1. A refractor and a reflector have the same diameter aperture. A disadvantage of the reflector is that
  2. reflectors allow in less light because it is blocked by the secondary mirror
  3. reflectors have less magnification
  4. reflectors do not direct all light to the same place
  5. None of the above
  6. How does the speed of light in glass compare to in space?
  7. Faster in glass
  8. Faster in space
  9. Same in both
  10. The bending of light around corners or edges is called:
  11. Resolution
  12. Refraction
  13. Interference
  14. Interferometer
  15. Diffraction
  16. The angular resolution of a telescope is determined by the ______of the telescope and the ______of the radiation being observed.
  17. Length, wavelength
  18. Length, color
  19. Size of the aperture, brightness
  20. Size of the aperture, wavelength
  21. None of the above
  22. The wavelength regions where the atmosphere does not absorb radiation are called
  23. Adaptive optics
  24. Atmospheric windows
  25. Light pollution
  26. Scintillation
  27. Seeing
  28. ______is a measure of the steadiness of the atmosphere during astronomical observations.
  29. Adaptive optics
  30. Atmospheric windows
  31. Light pollution
  32. Scintillation
  33. Seeing
  1. The Sun’s visible surface is called the
  2. Solar corona
  3. Solar Wind
  4. Sunspots
  5. Chromosphere
  6. Photosphere
  7. The process of converting hydrogen into helium in the Sun is called what?
  8. Radioactive decay
  9. Neutrino production
  10. Nuclear fusion
  11. Nuclear fission
  12. None of the above
  1. On average, the time between solar activity maxima is
  2. 1 year
  3. 11 years
  4. 22 years
  5. 33 years
  6. 111 years
  7. Colder visible regions of the Sun are called
  8. Aurora
  9. Coronal mass ejections
  10. Flares
  11. Sunspots
  12. Prominences
  13. On the Sun, the equator rotates faster than the area around the poles
  14. True
  15. False
  16. A parallax angle of 1 arcsecond means that an object is at a distance of ______.
  17. 1 A.U.
  18. 1 light-year
  19. 1 parsec
  20. 1 kiloparsec
  21. None of the above
  22. The method of triangulation is good for measuring distances
  23. Within the solar system
  24. To nearby stars
  25. Within our galaxy
  26. To nearby galaxies
  27. None of the above
  28. The amount of light reaching us from a star is called luminosity
  29. True
  30. False
  31. Star A is 10 times brighter than star B, but they have the same luminosity. Which star is closer?
  32. Star A
  33. Star B
  34. Neither, they are at the same distance
  35. Cold stars show absorption lines from heavy elements such as Calcium and Titanium oxide in their spectra.
  36. True
  37. False
  38. Differences in spectral type mainly reflect differences in
  39. Temperature
  40. Composition
  41. Neither
  42. As two stars orbit each other in a binary system their spectral lines get shifted due to eclipses
  43. True
  44. False
  45. The Stefan-Boltzmann Law gives the ______as a function of temperature
  46. Total power radiated
  47. Power radiated per unit area
  48. Power radiated per unit wavelength
  49. Flux received on Earth
  50. The wavelength where the emission peaks
  51. Suppose there are two stars A and B with the same luminosity. If star A is larger than star B, we can conclude
  52. Star A is more massive
  53. Star B is more massive
  54. The temperature of star B is lower
  55. The temperature of star A is lower
  56. Not enough information to conclude anything
  57. In an eclipsing binary star system, the maximum brightness occurs when
  58. The hotter star passes in front of the cooler star
  59. The colder star passes in front of the hotter star
  60. Both stars are visible
  61. The brightness of the system is constant
  62. None of the above
  63. Below is an H-R diagram. Stars in area #1 correspond to
  64. Main sequence stars
  65. Brown dwarfs
  66. Red giants
  67. Black holes
  68. White dwarfs

  69. In the above H-R diagram, stars in area #2 correspond to
  70. Main sequence stars
  71. Brown dwarfs
  72. Red giants
  73. Black holes
  74. White dwarfs
  75. In the above H-R diagram, stars in area #3 correspond to
  76. Main sequence stars
  77. Brown dwarfs
  78. Red giants
  79. Black holes
  80. White dwarfs
  81. The ______the mass of a star, the longer the time it spends in each stage of its evolution.
  82. Higher
  83. Lower
  84. Doesn’t Matter
  85. The Sun is classified as a high-mass star.
  86. True
  87. False
  88. Which of the following do not have enough mass to fuse hydrogen into helium?
  89. Main sequence stars
  90. Red giants
  91. Super giants
  92. White dwarfs
  93. Brown dwarfs
  94. Which of the following statements about molecular clouds is false?
  95. The contain hydrogen
  96. They contain particles coated in ice
  97. They contain helium
  98. They contain iron
  99. The entire cloud contracts as a whole leading to a gigantic protostar
  100. Stars spend most of their life on the main sequence
  101. True
  102. False
  103. When the core of a star contracts it ______.
  104. Heats up
  105. Cools down
  106. Its temperature stays the same
  107. When entering the giant phase, high mass stars don’t increase in luminosity as much as low mass stars
  108. True
  109. False
  110. When a star expands, the surface
  111. Turns red, heats up and power per square meter is increased
  112. Turns red, heats up and power per square meter is reduced
  113. Turns red, cools down and power per square meter is increased
  114. Turns red, cools down and power per square meter is reduced
  115. None of the above
  116. Variable stars that have no repeated pattern on a light curve are referred to as
  117. Irregular variables
  118. Cepheid variables
  119. RR Lyrae variables
  120. Mira variables
  121. Novae
  122. The area on the H-R diagram where most variable stars are found is called the
  123. Main sequence
  124. Supergiant region
  125. Giant region
  126. White dwarf region
  127. Instability strip
  128. The period-luminosity relation states that longer periods of a Cepheid variable imply higher luminosities
  129. True
  130. False
  131. From the figure below, where on the evolution time line does the star eject its outer layers?
  132. 1
  133. 2
  134. 3
  135. 4
  136. 5

  137. At the center of a low-mass planetary nebula is found a
  138. Planet
  139. Black Hole
  140. Neutron Star
  141. White Dwarf
  142. Variable star
  143. What best describes the evolution of a sun-like star from youngest to oldest?
  144. Black dwarf, white dwarf, red giant, main sequence, protostar
  145. Red giant, main sequence, white dwarf, black dwarf, protostar
  146. Protostar, main sequence, red giant, white dwarf, black dwarf
  147. Protostar, main sequence, red giant, black dwarf, white dwarf
  148. Protostar, red giant, main sequence, white dwarf, black dwarf
  149. Material from a companion star that accretes onto a white dwarf can trigger a chain reaction of fusion called
  150. Thermonuclear runaway
  151. Coronal ejection
  152. Electron degeneracy
  153. Mass transfer
  154. Recurrent nova
  155. When the mass of a white dwarf becomes less than the Chandrasekhar limit, it will collapse.
  156. True
  157. False
  158. In a high mass star ______cannot be used as fuel
  159. Oxygen
  160. Carbon
  161. Nitrogen
  162. Silicon
  163. Iron
  164. In the late stages of a high-mass red giant, elements are in layers with ______in the core and ______in the outermost layer.
  165. Hydrogen, Helium
  166. Helium, Hydrogen
  167. Helium, Silicon
  168. Iron, Hydrogen
  169. Hydrogen, Iron
  170. The sun will become a supernova
  171. True
  172. False

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