You have to decide which chapter each question comes from and whether that chapter will be on your exam. Be very careful.

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1. (10 points)

a) What are the two most abundant elements (types of atoms) in your typical cloud of interstellar dust and gas?

b) What element is being produced as a result of the fusion of H in the cores of stars?

c) What element is being produced as a result of the fusion of He in the cores of stars?

d) What is the population type of the Sun?

e) Which population type has the heavy metals, I or II?

2. (5 points) In a paragraph or two what causes the interior of a protostar to be hot? (This is before the nuclear fusion occurs.) I want an explanation. What do you start with and what causes (with details included) it to get hot?

3. (5 points) Place the following in the order in which they occur in the life of a star: a) main sequence star, b) protostar, c) planetary nebula, d) red giant, e) core has considerable non-fusing He in it.

4. (2 points) There are not many main sequence stars with masses less than 0.1 M

5. (2 points) The most massive main sequence stars quickly use up their H fuel in the core since the cores of these massive stars are quite small because of the intense crush of gravity and so there is only a small amount of H in the cores to start with. True or false?

6. (2 points) If we observe an O type main sequence star we know it is very young because a) these stars very rapidly evolve into B and A type main sequence stars, b) these stars very rapidly evolve into red giants, c) these stars produce so much energy that the gas surrounding them is heated and drifts away leaving a white dwarf, or d) when main sequence stars form they are O type stars. Pick one.

7. (2 points) A white dwarf eventually becomes a) a gray dwarf, b) a planetary nebula, c) a carbon star, or d) a much dimmer white dwarf. Pick one ___________

8. (2 points) All main sequence stars will eventually evolve into red giants. True or false?

9. (10 points)

a) About how long will a typical G type main sequence star remain on the main sequence?

b) Which main sequence stars have the most mass? (Give spectral type please.)

c) Which main sequence stars will remain on the main sequence the longest?

d) What will the Sun eventually evolve into? A white dwarf, a neutron star, or a black hole? Pick one.

e) What is the name of that little particle that is produced by the fusion in the core of main sequence stars which passes through practically anything without much effect?

10. (10 points) Suppose the hydrogen fusion rate in the core of a main sequence star slows down for some reason. List the steps which follow this slowing which eventually lead to the increase of fusion in the core and thus lead to stability. Give all the steps, in a logical order. (You can make a list of phrases, they do no have to be complete sentences.)

11. (5 points) In a few sentences why are the photospheres of red giants so cool despite the fact the red giants are very luminous.

12. (10 points) Make a sketch of a Hertzsprung Russell Diagram.

a) Show and label the main sequence, red giants, and white dwarfs.

b) Locate and label the Sun.

c) Circle those main sequence stars which will eventually evolve into black holes and label them as “eventual B.H.”

d) On the sketch show the evolutionary track of the protostar which evolves into a G type main sequence star and label this track as “protostar.”

13. (7 points) a) Starting with a large mass neutron star explain how a black hole forms? What happens to produce the black hole?

b) In reference to a black hole, what is the event horizon? What is special about the location of the event horizon?

14. (8 points) a) Consider a non-flat two dimensional universe called Flatland. Make a sketch showing the shape of Flatland which would correspond to a black hole. I.e. draw a 2D universe black hole.

b) Draw the shape that a 2D universe might have if it were curved in such a way that it were finite in size.

c) Draw the shape that a 2D universe might have if it were curved (not flat) and yet infinite. (To save paper you only need to draw a representative part of this universe.)

15. (10 points) a) In a few sentences what is Hubble’s law?

b) Does Hubble’s law mean that our galaxy is the center of the universe since everything is moving away from it? Yes or no? How would you explain your answer to someone who does not already know the answer. I.e. explain or justify your answer.

17. (2 points) We now have an answer for Olber’s paradox. The sky is not white because a) the universe with stars is not infinitely old, b) the universe would burn up if it were blowing white, c) the universe is open and thus light will travel forever in the universe, or d) the cosmic horizon is greater than the event horizon. Pick one.

18. (2 points) Astronomers currently get an estimate of the age of the universe by a) looking back in time to the point that one can not see any farther, b) looking at the turn-off point of globular clusters and estimating their ages, c) noting how much the cosmic background radiation has been Doppler shifter, or d) by noting how fast certain galaxies of known distances are traveling and working back to see when they were all clumped in one location. Pick one.

19. (2 points) We do not expect to find Earth-like planets circling stars in a globular cluster because a) none of the stars in globular clusters have rare metals that would be found in Earth-like planets, b) the stars in globular clusters are so close to each other that Earth-like planets can not have formed there, c) there is no clouds of dust and free gas found today in globular clusters and planetary systems are formed from dust and gas, or d) globular clusters formed before planets formed. Pick one.

20. (2 points) It is currently thought that the universe will expand forever. True or false?

21. (2 points) There was a time just after the Big Bang that the universe was opaque. True or false?

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This page prepared by C. Hartley, Director of the Ernest B. Wright Observatory at the Department of Physics at Hartwick College in the City of Oneonta, NY. More things from C. Hartley at his home.

All text, graphics and photgraphs copyright ©2003 by C. Hartley unless otherwise noted.