Name: Astro 102 S17 Test 1 Multiple Choice Identify the choice that best completes the statement or answers the question. 1. Your test is Version A. Please fill in the circle for A for this question on your form. a. Mark this one c. not this one b. not this one d. not this one 2. How is the distance to a star related to its parallax? a. Parallax gets bigger as distance gets bigger. b. Parallax gets bigger as distance gets smaller. c. Parallax is a measure of distance. d. As distance get bigger, parallax gets bigger twice as fast. 3. Which star in the figure below is closest to Earth? a. Star A c. The two stars are the same distance b. Star B d. Not enough information 4. The parallaxes of stars are most commonly measured in: a. Arcseconds c. Parsecs b. Arcminutes d. Degrees 5. Star R2D2 has a parallax angle of 2 arcseconds. Which of the following is a POSSIBLE distance for the star? a. 1 parsec c. 10 parsecs b. 0.5 parsecs d. 2 parsecs 6. What is the difference between magnitude and luminosity? a. Magnitude is how we see a star s brightness; luminosity is how much energy it emits. b. Luminosity is how we see a star s brightness; magnitude is how much energy it emits. c. Luminosity measures size; magnitude measures temperature. d. These are different names for the same property. 1
Name: 7. Imagine that you are viewing a star that has an apparent magnitude of 0.2 and is located about 100 parsecs away from us. Which of the following is most likely the star s absolute magnitude? a. 5.2 c. 0.5 b. 4.8 d. 0.2 8. The star named Capella has an apparent magnitude of 0 while the star named Polaris has an apparent magnitude of 2, which means that Capella appears Polaris in the night sky. a. brighter than c. as bright as b. dimmer than 9. What causes an a dark line in an continous spectrum? a. Atoms in a cool gas are emitting dark photons. b. Light is blocked by atoms causing a shadow on the spectrum. c. Light passing through a cool gas is absorbed by atoms. d. Light passing through a cool gas is bounced off atoms. 10. What determines the color (or wavelength) of an emission line in a spectrum? a. The type of neutron emitted c. The energy of the photon emitted b. The size of the atom d. The number of energy levels in an atom 11. Wien s Law relates the color and temperature of stars. Which is a correct statement according to Wien s Law? a. Cooler means white. c. Hotter means bluer. b. Cooler means bluer. d. Hotter means redder. 12. How do astronomers measure the surface temperature of a star? a. By observing binary systems. c. By observing its luminosity. b. By observing its spectrum. d. By observing its parallax. 13. Which of the follow best describes an absorption spectrum? a. a rainbow of all the colors b. a rainbow of all the colors except green c. a black background with several bright colored lines d. a rainbow of all the colors interrupted by narrow black lines 14. If you analyze the light from a hot, low density object (such as a cloud of interstellar gas), which type of spectrum do you see? a. Continuous spectrum c. Absorption spectrum b. Emission spectrum 15. Imagine that you are observing moonlight with a prism. Which of the following spectra would you observe? (Hint: What is the source of the moon s light?) a. Absorption spectrum c. Continuous spectrum b. Emission spectrum 16. You read in an article that a new O-type star has been discovered. What else do you know about this star by learning its spectral type? a. It is big and white. c. It is hot and blue. b. It is small and blue. d. It is cool and red. 2
Name: 17. Which sequence correctly lists the spectral classes of stars in order of decreasing temperature (from hottest to coolest)? a. A F O B M G K c. A B F G K M O b. O A B G F M K d. O B A F G K M 18. Since we can t measure the size of stars directly, what do astronomers measure to calculate the radius of a star? a. temperature and color c. luminosity and distance b. temperature and luminosity d. color and magnitude 19. You observe a very large and very hot star in the constellation Orion. On the same night, you observe another star in Orion that is much smaller but has the same temperature. Which star is more luminous? a. The larger star b. The smaller star c. They have the same temperature. d. There is insufficient information to determine this. 20. Which of the following statements is always true of two stars that have the same spectral type? a. They have the same absolute magnitude. b. They have the same size. c. They have the same temperature. d. They have the same luminosity. 21. Which of the following BEST describes a Hertsprung-Russell diagram? a. a graph of absolute versus apparent magnitude for stars b. a graph of luminosity versus spectral type for stars c. a graph of mass versus brightness for stars d. a graph of mass versus spectral type for stars 22. On a typical H-R diagram, where are the smallest stars (smallest radii) located? a. In the upper left corner c. In the upper right corner b. In the lower left corner d. In the lower right corner 23. The majority of stars on the Hertzsprung-Russell diagram belong to which group? a. Giant c. Supergiant b. Main Sequence d. White Dwarf 3
Name: 24. Consider the Hertzsprung-Russell Diagram depicted above. The long curve extending from upper left to lower right is the main sequence. The location of five stars (A E) are indicated on the diagram by star symbols. Please refer to this diagram when responding to the questions below. Which is the star most like the sun? a. A c. C b. B d. D 25. Which star is most likely to be a giant or supergiant? a. A d. D b. B e. E c. C 26. Which pair of stars has the same luminosity? a. A and E c. B and E b. A and B d. A and C 4
ID: A Astro 102 S17 Test 1 Answer Section MULTIPLE CHOICE 1. A 2. B 3. A 4. A 5. B 6. A 7. B 8. A 9. C 10. C 11. C 12. B 13. D 14. B 15. A 16. C 17. D 18. B 19. A 20. C 21. B 22. B 23. B 24. D 25. B 26. B 1