1. A star is born when it starts to produce heat by
   (A) gravitational contraction.
   (B) fusing hydrogen into deuterium.
   (C) fusing hydrogen into helium
   (D) fusing deuterium into hydrogen.
   (E) fusing deuterium into helium.

2. The stable life of a star starts when the star produces heat by
   (A) gravitational contraction.
   (B) fusing hydrogen into deuterium.
   (C) fusing hydrogen into helium
   (D) fusing deuterium into hydrogen.
   (E) fusing deuterium into helium.

3. Herbig-Haro objects are associated with
   (A) main sequence stars.
   (B) white dwarfs.
   (C) red giants.
   (D) T Tauri stars.
   (E) neutron stars.

4. Planets around other stars have been detected by
   (A) direct images.
   (B) proper motions of the stars.
   (C) nonthermal radio emission from these stars.
   (D) periodic radial velocity changes of the stars.
   (E) radio signals sent by aliens living on the planets.

5. The planets detected around other stars have masses comparable to the mass of
   (A) Mercury.
   (B) Earth.
   (C) Jupiter.
   (D) Neptune.
   (E) Pluto.

6. If a T Tauri star shows an emission line with a blue-shifted absorption component,
   (A) the blue-shifted absorption indicates an inflow to the star.
   (B) the blue-shifted absorption takes place in the disk around the star.
   (C) the star is viewed along the direction of its jets.
   (D) the emission component originates in jets.
   (E) all of the above.

7. A star clusters turn-off point of the main sequence on the HR diagram tells the cluster's
   (A) age.
   (B) size.
   (C) mass.
   (D) density.
   (E) number of members.

8. Which type of star stays on the main sequence for the longest time?
   (A) O star
   (B) A star
   (C) B star
   (D) K star
   (E) M star

9. Which of the following properties is the most responsible for the speed of stellar evolution?
   (A) radius
   (B) distance
   (C) mass
   (D) parallax
   (E) color

10. The Exclusion Principle says that
    (A) two identical particles cannot occupy the same state.
    (B) neutrons and protons cannot be next to each other.
    (C) all open clusters will dissolve over time.
    (D) electrons and positrons cannot co-exist.
    (E) globular clusters and open clusters do not co-exist.

11. During the triple-alpha process, ____ is fused into ____.
    (A) hydrogen into helium.
    (B) deuterium into helium.
    (C) helium into carbon.
    (D) helium into oxygen.
    (E) carbon into oxygen.

12. The lifetime of the Sun on the main sequence is
    (A) 10⁶ yr.
    (B) 10⁸ yr.
    (C) 10¹⁰ yr.
    (D) 10¹² yr.
    (E) unknown.

    HR Diagram

    
    For the following questions, use the HR Diagram above. For each question, write down the letter which corresponds to the proper location on the diagram. E is "none of the above" W, X, Y, and Z are stars labelled by the black filled circles.

13. Fusion of hydrogen in the center of a star occurs here.   C

14. The most massive stars come to this area after it runs out of hydrogen in its core.  A

15. The first place the Sun goes after it runs out of hydrogen in its core is here.  B

16. Stars spend most of their lifetimes here.  C

17. Star Y goes here at the very end of its evolution.  D

18. Star Y's interior starts to burn helium here.  B

19. Stars in this area has a carbon core.  D

20. Stars in this area end their life in supernova explosions.  A

21. Star Z is burning ___ at its core.
    (A) hydrogen
    (B) helium
    (C) carbon
    (D) iron
    (E) nothing

22. Star Y will eventually be surrounded by _____ at the end of its evolution.
    (A) a reflection nebula
    (B) an HII region
    (C) a planetary nebula
    (D) a supernova remnant
    (E) all of the above

23. Star W will eventually be surrounded by _____ at the end of its evolution.
    (A) a reflection nebula
    (B) an HII region
    (C) a planetary nebula
    (D) a supernova remnant
    (E) all of the above

24. Star X goes through a helium flash, which
    (A) makes the star's luminosity go up instantly.
    (B) does not produce any visible effects when it happens.
    (C) ejects helium from the surface of the star.
    (D) produce strong helium emission lines in the stellar spectrum.
    (E) produce strong helium absorption lines in the stellar spectrum.

25. Which star has an iron core toward the end of its evolution?
    (A) W
    (B)   X
    (C)   Y
    (D)   Z
    (E)   all of the above

26. Star W may turn into a ______ at the very end of its evolution.
    (A) white dwarf or a neutron star
    (B) a neutron star or a black hole
    (C) a white dwarf or a blackhole
    (D) luminous blue variable
    (E) red supergiant

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