TAKEN FROM HORIZONS 7TH EDITION CHAPTER 12 TUTORIAL QUIZ. When two objects of unequal masses orbit one another, the center of mass is located

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1 TAKEN FROM HORIZONS 7TH EDITION CHAPTER 12 TUTORIAL QUIZ 1. When two objects of unequal masses orbit one another, the center of mass is located a. closest to the less massive object. b. closest to the more massive object. c. at the center of the more massive object. d. exactly halfway between the two objects. answer: b 2. In order to detect an eclipsing binary star system, astronomers a. identify the two stars as a visual binary system. b. obtain the spectrum of the system. c. determine the trigonometric parallax of the system. d. graph the brightness of the system with respect to time. 3. Which of the following does NOT complicate the process of determining the mass of a binary star system? a. The orbits of the two stars may be elliptical rather than circular. b. The true size of the orbit is dependent upon our knowing the distance to the system. c. The orbital plane may be tilted with respect to our line of sight. d. The stars may not be main sequence stars, and therefore may not obey Kepler's laws of motion. file:///f /Astronomy/Lecture12PracticeQuiz1.txt (1 of 8)8/12/2005 9:02:44 AM

2 4. Binary stars are common, yet few can be analyzed completely. This is because a. none of these choices. All binary stars can be easily analyzed by using the largest telescopes. b. stars in a binary system generally orbit their center of mass too quickly. c. they must be far enough apart to be seen, but close enough to be seen orbiting one another. d. planets are easily misinterpreted as being binary star systems. 5. Which of the following statements is TRUE? a. An eclipsing binary system must also be a spectroscopic binary system. b. None of these choices is a correct statement. c. Visual binary systems are much more common than spectroscopic systems. d. The most massive star in a binary star system has the largest orbit. 6. Sirius and its white dwarf companion star are considered to be a(n) binary system. a. spectroscopic and visual. b. eclipsing c. spectroscopic d. visual 7. file:///f /Astronomy/Lecture12PracticeQuiz1.txt (2 of 8)8/12/2005 9:02:44 AM

3 If you wished to detect an eclipsing binary star system, what piece of equipment would you use in conjunction with a telescope? a. All of these choices b. Radio receiver that detects the Doppler effect from the moving stars. c. Spectrometer. d. Light meter that records the amount of light arriving from the system. 8. In addition to determining the masses of the stars in a binary star system, light curves are used to a. detect planets orbiting the stars. b. determine the temperatures of the stars. c. determine the diameters of the stars. d. calculate the tilt of the orbital plane of the system. 9. The study of globular clusters led to the discovery that the Sun is not located at the center of our Galaxy. The reasoning was that a. the Doppler effect reveals that the Sun and planets revolve around the globular clusters, which are known to be at the center of the Galaxy. b. star clusters revolve around the center of mass of the Galaxy. c. none of these choices. It was the study of Population I stars that led to the discovery. d. radio telescopes bounced radio waves off the globular clusters to locate them. answer: b 10. If you wish to observe clusters of Extreme Population II stars in the sky, you should look file:///f /Astronomy/Lecture12PracticeQuiz1.txt (3 of 8)8/12/2005 9:02:44 AM

4 a. in the direction of the constellation of Sagittarius. b. as far away from the band of the Milky Way as possible. c. along the ecliptic. d. along the entire length of the Milky Way band. 11. In the top-down theory, the positioning of globular clusters in the Milky Way galaxy a. explains why they contain the most active star-forming regions in the Galaxy. b. None of these choices. Their positioning is entirely random, and tells us nothing. c. explains why the Galaxy has spiral arms. d. reflects the shape of the original cloud from which the Galaxy formed. 12. Why do Population II stars contain lesser amounts of metals than Population I stars? a. Population II stars formed long ago, at which time metals were less common. b. Population II stars are very massive, and therefore are too hot to make metals. c. They don't. Population II stars contain more. d. Population I stars are older and have had more time to make more metals. 13. Where would you look if you wanted to observe a star with a low metal content? a. In an open star cluster. b. In a planetary nebula. file:///f /Astronomy/Lecture12PracticeQuiz1.txt (4 of 8)8/12/2005 9:02:44 AM

5 c. Between the spiral arms of a galaxy. d. In a globular star cluster. 14. The center of our Galaxy a. is in the direction of the vernal equinox (intersection of the ecliptic and celestial equator). b. is close to the constellation of Sagittarius. c. contains predominantly Population I extreme stars. d. contains the Seven Sisters (the Pleiades). answer: b 15. When we compare globular and open star clusters, we discover that a. globular clusters generally contain only 10,000 to 100,000 stars. b. globular clusters contain Population I stars; open clusters contain Population II stars. c. globular clusters remain permanently far from the galactic plane. d. open clusters are generally located close to or within the band of the Milky Way. 16. If you wish to observe Extreme Population I stars in the sky, you look a. within or close to the band of the Milky Way. b. at planetary nebulae. c. along the ecliptic. d. in globular clusters. 17. file:///f /Astronomy/Lecture12PracticeQuiz1.txt (5 of 8)8/12/2005 9:02:44 AM

6 Which of the following is NOT associated with our Galaxy's nucleus? a. instability strip. b. Sagittarius A. c. Population II intermediate stars. d. a ring of gas clouds. 18. The determination of the Sun's accurate location in our Galaxy is associated with a. Galileo. b. none of these choices. The Sun has always been known to be in the center of the Galaxy. c. Albert Einstein. d. the detection of Cepheid variable stars in star clusters in the halo of our Galaxy. 19. Astronomers believe a massive black hole might reside in the nucleus of the Galaxy. The evidence they provide is that a. if there weren't a black hole there, stars in the Galaxy would just drift out into space. b. it is dark in the nucleus, and no radiation has yet been detected. c. motions of stars near the center suggest the presence of a single, massive object. d. stars in the nucleus are disappearing from our view. 20. We know that the Milky Way galaxy has spiral arms because we file:///f /Astronomy/Lecture12PracticeQuiz1.txt (6 of 8)8/12/2005 9:02:44 AM

7 a. have sent satellite probes out to determine their sizes and locations. b. can observe them directly with optical telescopes. c. can detect the hydrogen gas associated with them using radio telescopes. d. trace them using Cepheid variable stars. 21. Compared to globular star clusters, open star clusters tend to be a. poorer in metals and older. b. richer in metals and older. c. poorer in metals and younger. d. richer in metals and younger. 22. The component of our Galaxy that contains most of the dark matter that, to date, has yet to be identified: a. stellar halo. b. nuclear bulge. c. spiral arms. d. galactic corona. 23. A photograph of the sky toward the center of our Galaxy reveals which of the following about the center itself? a. The center is swarming with dense concentrations of stars. b. The center is swarming with dense concentrations of gas and dust. c. Nothing. Only stars in the neighborhood of the Sun are visible. d. The center is swarming with dense concentrations of stars, gas and dust. file:///f /Astronomy/Lecture12PracticeQuiz1.txt (7 of 8)8/12/2005 9:02:44 AM

8 24. Harlow Shapley is credited with the important discovery of the Sun's true location in the disk shaped cloud of stars of the Milky Way. Following that, he attempted to convince other astronomers that a. none of these choices. b. the Milky Way was not the only galaxy in the universe. c. the Sun was but an average star amongst all of those stars. d. the cloud of stars was not disk-shaped at all, but rather in a large spherical shape. answer: b 25. The reason that spiral arms stand out in photographs of distant galaxies is because a. spiral density waves' gravitation pulls stars to their locations, which are in the shape of spirals. b. there is very little gas and dust to conceal the stars there. c. that is where the greatest concentrations of stars are located. d. that is where star formation takes place. file:///f /Astronomy/Lecture12PracticeQuiz1.txt (8 of 8)8/12/2005 9:02:44 AM