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Unformatted text preview: ASTRONOMY 122 Exam 3 February 24, 2009 1. Why does the H-R diagram of a globular cluster NOT contain any stars with high luminosity and high temperature on the main sequence? b. these high-mass stars have evolved away from the main sequence 2. What is a stellar association? b. loosely bound group of newborn stars 3. Approximately what temperature is required in a collapsing protostar to ignite nuclear burning? d. 8,000,000 K 4. What do many astronomers regard as a triggering mechanism for star formation? a. passage of a shock wave 5. What is unusual about the Algol binary? a. The most massive of the two stars is still on the main sequence 6. What is the approximate density of dust in the interstellar medium? b. 1000 dust particles/km 3 7. What is the approximate density of atoms in the interstellar medium? d. 1 atom/cm 3 8. Newborn star clusters are often found with a. emission nebulae 9. Which development within the deep interior of the Sun will eventually lead to major changes? d. the build-up of helium in the core 10. How does a medium mass star evolve, on the H-R diagram, at the end of its main sequence lifetime? c. to higher luminosity and lower surface temperature 11. Infrared stars within the Orion Nebula are examples of which stage of stellar evolution? b. protostar and young star 12. The most likely site for the manufacture of heavy elements (beyond hydrogen and helium) in the Universe is c. in the deep interiors of stars 13. Which class of stars is the oldest? c. stars with less abundance of heavy elements 14. The interstellar gas (by number of atoms) is a. 90% hydrogen, 9% helium, traces of other atoms 15. Which of the following processes requires the highest temperature to proceed? a. triple alpha process----> b. Carbon fusion c. CNO cycle d. proton-proton chain reaction 16. A star that emits a planetary nebula is likely to a. become a white dwarf 17. The speed of a neutrino is close to d. The speed of light 18. Which of the following would be a reasonable age for a red giant star in the sky today? c. 10,000,000,000 years 19. The path drawn on the H-R diagram below represents the change in b. a Sun-like star during the "birth" of the star 20. Where is one most likely to find a white dwarf star?...
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- Spring '10
- White dwarf, Horsehead Nebula