29:50 Modern Astronomy
Fifth Hour Exam
December 15, 1997
Form A
Although the lesson is ever the same, people ever fail to understand
Heraclitus

1. For stars on the Main Sequence, there is a correlation between which of the two following stellar properties. Correlation means as one characteristics increases, the other one does too.
   (a) surface temperature and chemical composition
   (b) luminosity and position in the galaxy
   (c) mass and age
   (d) mass and luminosity X
   (e) age and luminosity
   
2. Which of the following kinds of astronomical objects comprise the accumulations of ``raw material'' from which stars form, and which are in fact the sites of star formation?
   (a) neutron stars
   (b) planetary nebulae
   (c) giant molecular clouds X
   (d) elliptical galaxies
   (e) globular star clusters
   
3. The nearest example of a large star formation region is
   (a) the Helix Nebula
   (b) the globular star cluster M13
   (c) the Orion Nebula X
   (d) Alpha Centauri
   (e) the Cygnus Loop
   
4. Which of the following represents a group of recently formed stars?
   (a) the globular cluster M13
   (b) the bright star Arcturus
   (c) the Andromeda galaxy
   (d) the Pleiades and and h Persei X
   (e) the Population II stars in the galactic halo
   
5. Which of the following statements is true about the formation of stars in the Milky Way galaxy?
   (a) Star formation is presently occurring in at least 2000-3000 locations throughout the Milky Way. X
   (b) Star formation ceased shortly after the formation of the Milky Way.
   (c) Star formation occurred in the early history of the Milky Way, but ceased about the time that the Sun formed.
   (d) Star formation is occurring at between 20 and 30 places, the most active being the Taurus-Auriga association.
   (e) Star formation occurs in cycles of 2.75 billion years in the Milky Way.
   
6. Which of the following statements about the Main Sequence lifetimes of stars is correct?
   (a) We do not know how long stars last on the Main sequence.
   (b) The Main Sequence lifetime of a star is pretty much independent of its spectral type.
   (c) The stars with the shortest Main Sequence lifetimes are the red dwarfs.
   (d) A luminous, spectral class O star will last longer on the Main Sequence than a star like the Sun.
   (e) The more massive a star, the shorter the time it lasts on the Main Sequence. X
   
7. You are abducted by a group of really stupid space aliens, who nonetheless have a very fast spaceship. Later, while serving you peanuts and complimentary soft drinks, they tell you that they are going to the globular star cluster M92, which is about 14 billion years old, and upon arrival, will search for a solar type star where you might feel at home. As a successful Modern Astronomy student, you point out to them the error in their thinking. What is it?
   (a) M92 is not a globular star cluster.
   (b) There are no globular star clusters in the Milky Way galaxy.
   (c) Globular star clusters don't contain solar type stars.
   (d) All the stars in a globular star cluster are solar type stars.
   (e) A star cluster 14 billion years old won't have any solar type stars.X
   
8. What is the source of the Sun's energy?
   (a) the proton-proton cycle occurring in its outer layers
   (b) chemical reactions occurring in the center of the Sun.
   (c) the proton-proton cycle in its core. X
   (d) the triple Alpha process in its core.
   (e) matter-antimatter annihilation in the solar core.
   
9. Billions of years in the future, the Sun will have become one of the following objects as its ``end point'', i.e. the end of its stellar evolution. Which is it?
   (a) red supergiant
   (b) white dwarf X
   (c) neutron star
   (d) red dwarf
   (e) T Tauri star
   
10. In the Hertzsprung-Russell diagram, there are luminous, red stars above (more luminous) and to the right (redder) than the Main Sequence. How, if at all, do they fit into the scheme of evolution of stars?
    (a) These stars are in a phase of their life prior to the Main Sequence.
    (b) These stars correspond to the phase of stellar life after the Main Sequence. X
    (c) These stars are the final ``end products'' of stellar evolution.
    (d) These stars are distinct from the Main Sequence stars; Main Sequence stars never become the red, luminous ones, or vice-versa.
    (e) These stars differ from the Main Sequence in that nuclear reactions do not occur in them.
    
11. Which of the following statements is correct regarding the existence (or nonexistence) of molecules in interstellar space?
    (a) No molecules have even been discovered in interstellar space, although there do not seem to be fundamental objections to their existence.
    (b) It is not possible for molecules to exist in the interstellar medium, since the interstellar medium is a plasma or ionized gas.
    (c) Molecules have been discovered, with two or three atoms, such as CO or H O, but not more.
    (d) Complicated molecules exist in interstellar space, with molecules containing as many as eleven atoms. X
    (e) Molecules in the interstellar medium are exclusively extremely complicated forms such as glycines and organic acids.
    
12. Which of the following numbers is a good estimate for the age of the universe.
    (a) 500 - 1000 million years
    (b) 12 - 15 billion years X
    (c) 50 - 100 billion years
    (d) 4 - 5 billion years
    (e) 200 - 300 billion years
    
13. What kind of star is the Sun?
    (a) a spectral class G Main Sequence star. X
    (b) a spectral class O star.
    (c) a red dwarf
    (d) an asymptotic giant branch star
    (e) a Cepheid variable.
    
14. Inspired by having taken this course, you decide to switch your major from Comparative Literature to Nuclear Physics. Ten years from now, you find that the energy released in the proton-proton cycle is only half what had previously been believed (and which was taught in this course). Which of the following startling astronomical conclusions would you immediately reach?
    (a) The Sun is a red supergiant instead of a Main Sequence star.
    (b) The explanation for supernovae discussed in class must be incorrect.
    (c) The luminosity of Main Sequence stars must be twice what we have thought it was.
    (d) The Sun is about ready to evolve off the Main Sequence. X
    (e) Nuclear reactions are inadequate to the luminosity requirements of red dwarf stars.
    

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