1. Copyright © 2010 Pearson Education, Inc. Clicker Questions Chapter 10 Measuring the Stars

2. Copyright © 2010 Pearson Education, Inc. Question 1 Stellar parallax is used to measure the a) sizes of stars. b) distances of stars. c) temperatures of stars. d) radial velocity of stars. e) brightness of stars.

3. Copyright © 2010 Pearson Education, Inc. Question 1 Stellar parallax is used to measure the a) sizes of stars. b) distances of stars. c) temperatures of stars. d) radial velocity of stars. e) brightness of stars. Parallax can be used to measure distances to stars accurately to about 200 parsecs (650 light-years).

4. Copyright © 2010 Pearson Education, Inc. Question 2 The angle of stellar parallax for a star gets larger as the a) distance to the star increases. b) size of the star increases. c) size of the telescope increases. d) length of the baseline increases. e) wavelength of light increases.

5. Copyright © 2010 Pearson Education, Inc. Question 2 The angle of stellar parallax for a star gets larger as the a) distance to the star increases. b) size of the star increases. c) size of the telescope increases. d) length of the baseline increases. e) wavelength of light increases. Astronomers typically make observations of nearby stars 6 months apart, making the baseline distance equal to 2 AU (Astronomical Units).

6. Copyright © 2010 Pearson Education, Inc. Question 3 You can best model the size and distance relationship of our Sun & the next nearest star using a) a tennis ball here, and one on the Moon. b) two beach balls separated by 100 city blocks. c) two grains of sand 100 light-years apart. d) two golf balls 100 km apart. e) two baseballs 100 yards apart.

7. Copyright © 2010 Pearson Education, Inc. Question 3 You can best model the size and distance relationship of our Sun & the next nearest star using a) a tennis ball here, and one on the Moon. b) two beach balls separated by 100 city blocks. c) two grains of sand 100 light- years apart. d) two golf balls 100 km apart. e) two baseballs 100 yards apart. The Sun is about one million miles in diameter. The next nearest star is about 25 million times farther away.

8. Copyright © 2010 Pearson Education, Inc. Question 4 A star’s proper motion is its a) true motion in space. b) apparent shift as we view from opposite sides of Earth’s orbit every six months. c) annual apparent motion across the sky. d) motion toward or away from us, revealed by Doppler shifts. e) orbital motion around the galaxy.

9. Copyright © 2010 Pearson Education, Inc. Question 4 A star’s proper motion is its a) true motion in space. b) apparent shift as we view from opposite sides of Earth’s orbit every six months. c) annual apparent motion across the sky. d) motion toward or away from us, revealed by Doppler shifts. e) orbital motion around the galaxy. A star’s “real space motion” combines its apparent proper motion with its radial motion toward or away from Earth.

10. Copyright © 2010 Pearson Education, Inc. Question 5 In the stellar magnitude system invented by Hipparchus, a smaller magnitude indicates a _____ star. a) brighter b) hotter c) cooler d) fainter e) more distant

11. Copyright © 2010 Pearson Education, Inc. Question 5 In the stellar magnitude system invented by Hipparchus, a smaller magnitude indicates a _____ star. a) brighter b) hotter c) cooler d) fainter e) more distant

12. Copyright © 2010 Pearson Education, Inc. Question 6 A star’s apparent magnitude is a number used to describe how our eyes measure its a) distance. b) temperature. c) brightness. d) absolute luminosity. e) radial velocity.

13. Copyright © 2010 Pearson Education, Inc. Question 6 A star’s apparent magnitude is a number used to describe how our eyes measure its a) distance. b) temperature. c) brightness. d) absolute luminosity. e) radial velocity.

14. Copyright © 2010 Pearson Education, Inc. Question 7 The absolute magnitude of a star is its brightness as seen from a distance of a) one million km. b) one Astronomical Unit. c) one light-year. d) ten parsecs. e) ten light-years.

15. Copyright © 2010 Pearson Education, Inc. Question 7 The absolute magnitude of a star is its brightness as seen from a distance of a) one million km. b) one Astronomical Unit. c) one light-year. d) ten parsecs. e) ten light-years. Astronomers use a distance of 10 parsecs (about 32 light-years) as a standard for specifying and comparing the brightnesses of stars.

16. Copyright © 2010 Pearson Education, Inc. Question 8 Which of the following quantities do you need in order to calculate a star’s luminosity? a) apparent brightness (flux) b) Doppler shift of spectral lines c) color of the star d) distance to the star e) a and d

17. Copyright © 2010 Pearson Education, Inc. Question 8 a) apparent brightness (flux) b) Doppler shift of spectral lines c) color of the star d) distance to the star e) a and d Which of the following quantities do you need in order to calculate a star’s luminosity?

18. Copyright © 2010 Pearson Education, Inc. Question 9 What are the two most important intrinsic properties for classifying stars? a) distance and surface temperature b) luminosity and surface temperature c) distance and luminosity d) mass and age e) distance and color

19. Copyright © 2010 Pearson Education, Inc. Question 9 What are the two most important intrinsic properties for classifying stars? a) distance and surface temperature b) luminosity and surface temperature c) distance and luminosity d) mass and age e) distance and color The H–R diagram plots stars based on their luminosities and surface temperatures.

20. Copyright © 2010 Pearson Education, Inc. Question 10 Wien’s law tells us that the hotter an object, the _____ the peak wavelength of its emitted light. a) longer b) more green c) heavier d) shorter e) more constant

21. Copyright © 2010 Pearson Education, Inc. Question 10 Wien’s law tells us that the hotter an object, the _____ the peak wavelength of its emitted light. a) longer b) more green c) heavier d) shorter e) more constant Wien’s law states that hotter stars appear more blue in color, and cooler stars appear more red in color.

22. Copyright © 2010 Pearson Education, Inc. Question 11 We estimate the surface temperature of a star by using a) its color. b) the pattern of absorption lines in its spectrum. c) Wien’s law. d) differences in brightness as measured through red and blue filters. e) All of the above are used.

23. Copyright © 2010 Pearson Education, Inc. Question 11 We estimate the surface temperature of a star by using a) its color. b) the pattern of absorption lines in its spectrum. c) Wien’s law. d) differences in brightness as measured through red and blue filters. e) All of the above are used.

24. Copyright © 2010 Pearson Education, Inc. Question 12 Which spectral classification type corresponds to a star like the Sun? a) O b) A c) F d) G e) M

25. Copyright © 2010 Pearson Education, Inc. Question 12 a) O b) A c) F d) G e) M The OBAFGKM classification scheme is based on absorption lines. Which spectral classification type corresponds to a star like the Sun?

26. Copyright © 2010 Pearson Education, Inc. Question 13 The key difference between the spectra of B stars and G stars is a) B stars show strong hydrogen lines; G stars show weaker hydrogen lines. b) B stars show few metal lines; G stars show many. c) B stars have no metal atoms. d) G stars have no hydrogen atoms. e) Both a and b are true.

27. Copyright © 2010 Pearson Education, Inc. Question 13 The original OBAFGKM sequence was arranged alphabetically by the strength of hydrogen absorption lines. B stars had strong hydrogen lines, G stars had weak lines. The key difference between the spectra of B stars and G stars is a) B stars show strong hydrogen lines; G stars show weaker hydrogen lines. b) B stars show few metal lines; G stars show many. c) B stars have no metal atoms. d) G stars have no hydrogen atoms. e) Both a and b are true.

28. Copyright © 2010 Pearson Education, Inc. Question 14 Astronomers can estimate the size of a star using a) apparent brightness. b) direct observation of diameter. c) temperature. d) distance to the star. e) a, b, and c are all true.

29. Copyright © 2010 Pearson Education, Inc. Question 14 Astronomers can estimate the size of a star using a) apparent brightness. b) direct observation of diameter. c) temperature. d) distance to the star. e) a, b, and c are all true. Brightness and temperature are used to plot the star on an H–R diagram, and indicate its approximate size. Some stars are large enough to measure directly.

30. Copyright © 2010 Pearson Education, Inc. Question 15 Eclipsing binary stars are very useful for determining the a) ages of stars. b) absolute luminosities of stars. c) masses of stars. d) distances to stars. e) rotation rates of stars.

31. Copyright © 2010 Pearson Education, Inc. Question 15 Eclipsing binary stars are very useful for determining the a) ages of stars. b) absolute luminosities of stars. c) masses of stars. d) distances to stars. e) rotation rates of stars. Analysis of the lightcurve of an eclipsing binary star system can reveal the masses of the stars.

32. Copyright © 2010 Pearson Education, Inc. Question 16 What is the single most important characteristic in determining the course of a star’s evolution? a) density b) absolute brightness c) distance d) surface temperature e) mass

33. Copyright © 2010 Pearson Education, Inc. Question 16 What is the single most important characteristic in determining the course of a star’s evolution? a) density b) absolute brightness c) distance d) surface temperature e) mass A star’s mass determines how fast it forms, its luminosity on the main sequence, how long it will shine, and its ultimate fate.