Download Astronomy II (Astr 1020) Homework #5 - Prof. Richard Ignace and more Assignments Astronomy in PDF only on Docsity! Astronomy II (Astr 1020) Spring 2008 Prof Richard Ignace HOMEWORK #5 Notes: You will need a calculator, a pencil, and a standard scantron. Each question has one correct answer. Choose the best answer for each. Mark your answer on the scantron. This homework is due at the beginning of class on March 27. Late homeworks will not be accepted. 1. A galaxy that is four times as far away as another appears will based on the Hubble law move times as fast as the closer one a) 1/16 b) 1/4 c) just as fast d) 4 e) 16 2. Elliptical galaxies have few if any new stars. Why is this? a) The central black holes of ellipticals have consumed all the gas that would have made new stars. b) Ellipticals never have central black holes, and it is these that would normally stimulate star formation. c) Ellipticals form without any gas. d) All the gas has been used up in previous generations of star formation. e) The gravity of ellipticals is too small to keep any gas. 3. Why is it that galaxy mergers produce a lot of star formation (referred to as a “starburst”)? a) The collision leads to the compression of gas clouds, and so higher densities and rapid cloud collapse. b) The collision of the central black holes of the two galaxies forces them to “burp” all the stars they have ever previously engulfed. c) The collision leads to stars hitting each other, resulting in splits and the production of extra stars. d) The collision leads to stars passing close to each other, and this gravitationally “rips” off the outer atmospheric layers of the stars to form new clouds of gas and new star formation. 1 4. Which of the following statements about globular clusters is NOT true: a) A globular cluster is a large collection of 100,000 to 10 million stars orbiting each other. b) There are about a hundred globular clusters in orbit around our galaxy. c) Many globular clusters have ages greater than 10 billion years d) Globular clusters tend to have a very low heavy element content e) You can usually find globular clusters in the spiral arms 5. Which of the following is a difference between a typical halo star and the Sun. a) A halo star will tend to be older. b) A halo star will tend to have fewer heavy elements. c) A halo star tends not to be found in the Milky Way disk. d) All of the above are valid differences. e) None of the above are valid differences. 6. Based upon what we know about the structure of the Milky Way galaxy and our location in it, which one of the following is true of the sky as we observe it? a) Stars in the Milky Way appear to be evenly distributed over the whole sky. b) Almost all of the stars we see are in the Milky Way halo since the disk is filled with so much intervening dust and gas. c) There appear to be more galaxies at low galactic latitudes because the halo material of the Milky Way blocks our view at high galactic latitudes. d) There appear to be more galaxies at high galactic latitudes because there is less dust and gas blocking the line of sight out of the Milky Way in that direction. 7. In the Milky Way galaxy, the Sun is located a) in a spiral arm, about 2/3 of the way out from the center. b) very near the nuclear bulge of the galaxy. c) in a spiral arm on the outer edge of the galaxy. d) in the galactic halo. e) in the outer parts of the large globular cluster known as M13. 8. Select the correct statement. a) Globular clusters tend to be located in the Milky Way disk. b) Population II stars are metal-poor. c) Population I stars are metal-poor. d) Open clusters tend to be located in the Milky Way halo. 2
