1. Open clusters are found in the
a) Milky Way (the disk of our Galaxy)
2. Globular clusters are
e) all of the above: found in the Galaxy's halo; much more
massive than open clusters; are the oldest objects known; are
much rarer than open clusters
3. Old star clusters are missing
b) their upper main sequences (as high mass stars die
first)
4. How old are the oldest star clusters in billions of years?
d) 12
5. The classic case of a white dwarf is the companion to
d) Sirius
6. Diffuse nebulae shine by
a) photoionization by ultraviolet light and subsequent
recombination
7. Interstellar dust is made mostly of
d) silicon and carbon
8. Most of the gas within a molecular cloud is in the form of
e) molecular hydrogen
9. Which is not a molecule found in interstellar space?
e) protein
10. The cores of stars just beginning life on the main sequence are
made mostly of
a) hydrogen
11. What helps slow a rotating cloud that helps it become a
star?
a) cosmic rays and the galactic magnetic field
12. What chills the dark clouds so that stars can form?
d) dust that blocks starlight
13. Stars are currently being born in
b) giant molecular clouds
14. T Tauri stars and Herbig-Haro objects are associated with
a) dark dust clouds
15. Developing stars form disks because of the conservation of
d) angular momentum
16. The age of a globular cluster is found from
b) the highest-mass stars found in the cluster
17. What observations provide evidence for the existence of planets
orbiting other stars?
e) all of the above: direct observation of the planets;
transits across the stellar disk; observations of dusty disks
around new stars; slight variations in the stars' radial
velocities
18. When the Sun was born, it was
b) somewhat dimmer than now
19. Which kind of main sequence star will live the shortest period
of time and explode?
b) O
20. The nuclear-fusing core of the Sun is
b) slowly contracting and heating
21. The Sun will create a
d) all of the above: planetary nebula; white dwarf; giant
star
22. What evidence is there for intelligent life in the Universe
(other than ourselves)?
e) none
23. Where on the HR diagram do we find brown dwarfs?
b) below the lower end of the hydrogen-fusing main
sequence
24. Above what mass (in solar masses) are main sequence stars
expected to explode, that is, to become supernovae?
c) 10
25. A star climbing the giant branch for the first time has a core
made of
a) helium
26. What keeps the Sun from rapid collapse, that is, what supports
it?
b) thermonuclear fusion in the core
27. The fusion of what element stops the first ascent of the giant
branch?
a) helium
28. A star climbing the giant branch for the second time has a core
made of
c) carbon and oxygen
29. What does helium fuse into?
d) carbon
30. What kinds of stars fuse helium?
d) giant stars
31. White dwarfs are made mostly of
c) carbon and oxygen
32. Stars like Mira, those climbing the giant branch for the second
time, will turn into or produce
b) planetary nebulae
33. What stage of stellar life follows the planetary nebula?
d) white dwarf
34. White dwarfs are formed by stars that start off in the mass
range
a) 0.8 to 10 solar (Below 0.8 solar, no star has had time to
evolve.)
35. The maximum allowed mass for a white dwarf is (in solar
masses)
d) 1.4 (called the Chandrasekhar limit, above which it will
collapse)
36. White dwarfs do not collapse under their own gravity because
of
e) the pressure of degenerate electrons
37. What do planetary nebulae have at their centers?
a) new white dwarfs
38. Where does a lot of the interstellar dust come from?
c) Mira variables
39. A high-mass star that generates an iron core will become a
b) core-collapse (Type II) supernova
40. The upper mass limit for neutron stars (in solar masses) is
about
d) 3 (Neutron stars are supported by degenerate neutrons.)
41. The "event horizon" of a black hole (the apparent "surface") is
the surface at which
d) the escape velocity equals the speed of light
42. From an isolated black hole (one with no companion or nearby
gas) we would observe or detect
b) gravity but no light
43. The brightest kind of "star" is the
b) core-collapse supernova
c) Type Ia white dwarf supernova
44. Cosmic rays are
d) high-speed atomic nuclei launched by supernovae
45. Pulsars are
c) rotating neutron stars
46. An ordinary white dwarf can produce a supernova if
a) it has a companion
47. What evidence is there that black holes actually exist?
c) we see otherwise normal stars that are also bright X-ray
sources (and mass transfer binary systems)
48. The iron content of the Galaxy
c) is currently increasing (because of continuous input from
supernovae)
49. The Crab Nebula is
d) a supernova remnant
50. What is the contribution of supernovae to star and planet
formation?
d) all of the above: shock waves; cosmic rays; iron