Astronomy - Test 3
Summer 2011
Test form A
Name ________________________
Do not forget to write your name and fill in the bubbles with your student number, and
fill in test form B on the answer sheet. Write your name above as well. You have 55
minutes. For each question, mark the best answer. The formulas you may want are:
3.26 ly
d
p
4
L T   R 
  

L  T   R 
2
L = 4d2B
1. Star X is a main sequence star. It is the same spectral type (G2) as the Sun. What
does this tell us about how star X compares to the Sun?
A) It will have about the same temperature, luminosity, and radius
B) It will have about the same temperature and luminosity, but not necessarily the
same radius
C) It will have the same temperature, but not necessarily the same luminosity nor
radius
D) It will have the same luminosity, but not necessarily the same radius nor
temperature
E) This gives us no information about its temperature, luminosity nor radius
2. Which of the following is a surprise that we learned about when studying extrasolar
planets?
A) Extrasolar planets are extremely rare
B) Earth size planets in orbit around similar stars are extremely common
C) Icy planets are much more common than rocky plaents
D) Planets almost always orbit in nearly circular orbits
E) It is not uncommon for giant planets to be in very close orbits around their stars
3. What determines the size of a white dwarf?
A) Temperature: hotter is smaller
B) Temperature: hotter is larger
C) Mass: more massive is smaller
D) Mass: more massive is larger
E) A combination of temperature and mass
4. How does a high mass main sequence star differ from a low mass main sequence
star?
A) It is hotter and more luminous
B) It is hotter and less luminous
C) It is cooler and more luminous
D) It is cooler and less luminous
E) The mass does not tell you anything about how hot or luminous it is
5. Planetary nebulas are large glowing spheres of gas surrounding a dying star. What is
the source of power for this glow?
A) Fusion reactions occurring in the nebula
B) Chemical reactions in the nebula
C) Collisions of the high-speed gas in the nebula
D) Ultraviolet light coming from the dying star
E) Neutrinos coming from the dying star
6. The Sun is fueled by nuclear “burning.” In what way is nuclear burning different
from conventional chemical burning?
A) It doesn’t actually consume any fuel
B) It completely destroys the material, so there is no “burned” material left over
C) It doesn’t require heat
D) It doesn’t require oxygen
E) None of the above are correct
7. For a low mass star, what stage immediately follows the main sequence?
A) White dwarf
B) Planetary nebula
C) Double shell burning
D) Core helium burning
E) Red giant
8. Which of the following tells you the total amount of power coming out of a star?
A) Brightness B) Luminosity C) Color D) Spectral type E) Temperature
9. Arrange the photosphere, chromosphere, and corona in order from coldest to hottest
A) Corona, chromospheres, photosphere
B) Chromosphere, corona, photosphere
C) Chromosphere, photosphere, corona
D) Corona, photosphere, chromospheres
E) Photosphere, chromospheres, corona
10. Star A and Star B have the same brightness, but star A is more luminous than star B.
Which star is farther away?
A) Star A
B) Star B
C) If they are the same brightness, they must be the same distance away
D) There is insufficient information to figure out which is farther away
E) I have no idea; please mark this one wrong
11. Which of the following is true about the process of fusing helium that occurs in late
stages of stellar evolution?
A) It occurs for a very long time, much longer than hydrogen burning
B) It produces a lot less energy than hydrogen fusion
C) It can occur only in the outer layers of a star, never the core
D) It can occur at lower temperatures than hydrogen fusion
E) It converts some of the helium back into hydrogen
12. What is believed to occur when two neutron stars in close orbit come together?
A) They cause a massive star supernova
B) They transfer gas and cause a nova
C) They produce periodic X-rays – an X-ray pulsar
D) They merge to form a black hole
E) Fusion is restarted in the stars and they return to the main sequence
13. When we looked at the sun through a telescope, we saw a dark spot on the surface.
This dark spot is caused by
A) A concentration of carbon and other dark material on the Sun’s surface
B) Concentrated magnetic fields, preventing circulation and cooling a place on the
Sun
C) Opaque materials forming a cloud in the Sun’s corona
D) A region where nuclear fusion has stopped, probably due to a lack of hydrogen
E) An inferior planet passing between us and the Sun, probably Mercury
14. The Sun is currently in which stage?
A) Protostar
B) Red giant
C) Core helium burning
D) Main sequence
E) Double shell burning
15. After a massive star undergoes a supernova explosion, what remains at the center?
A) A neutron star or black hole
B) A white dwarf
C) A supernova remnant
D) A planetary nebula
E) Nothing
16. Which of the following is caused, ultimately, by the solar wind?
A) Earth’s atmosphere
B) Earth’s magnetic field
C) The aurora borealis and aurora australis
D) Global warming
E) Winds on the surface of the Earth
17. The number of sunspots seems to be rising over the past couple of years, and will
probably continue to do so over the next few years. How would you expect the
number of flares, prominences, coronal mass ejection incidents and so on to change
over the same time frame?
A) They should all also be rising
B) They should be all falling
C) They should all probably stay about the same
D) Prominences and flares should increase, but coronal mass ejections should
decrease
E) Coronal mass ejections should increase, but prominences and flares should
decrease
18. Which of the following is a technique that was discussed in class for detecting
extrasolar planets in the conceivable future?
A) Sending spacecraft to other stars to look for them
B) Looking for the spectrum from planets mixed in with the spectrum of the star
C) Seeing if the star’s position wobbles back and forth from the gravitational
influence of the planet
D) Detecting the gases emitted by planet’s evaporating atmospheres
E) Measuring the density of distant stars, which has to be corrected for any rocky
planets that might be orbiting them
19. In class I showed you pictures of giant arcs of glowing stuff sticking out of the Sun.
What is controlling the shapes of these glowing arcs?
A) The gas is simply shooting out of the Sun and falling back, following the laws of
gravity
B) There are semi-solid plasma conduits guiding the gases
C) The Sun worships the Giant Space Turtle, and is trying to sculpt this shape on its
surface
D) The gases are riding on top of supergranules of the Sun’s convection
E) The arcs are following magnetic field lines protruding from the surface of the Sun
20. Which of the following can be found in the nucleus of atoms?
A) Protons (only)
B) Neutrons (only)
C) Electrons (only)
D) Protons and neutrons, but not electrons
E) Protons, neutrons, and electrons
21. Why is it that old clusters tend to look more red, while younger clusters tend to look
more blue?
A) Young clusters tend to move towards us (blue shift), and old ones away (red shift)
B) Stars lose mass as they age, making them into low mass K and M stars, but start
as O and B stars
C) Gas and dust accumulates around clusters, reddening them with age
D) The bright, blue O and B stars tend to dominate young clusters, but these massive
stars are long dead in old clusters
E) Young clusters contain no (red) giants, but in old clusters these very large stars
have swallowed all the smaller stars
22. What is the basic difference between a plasma and an ordinary gas?
A) Plasmas have atoms that have been stripped of some or all of their electrons
B) Plasmas emit electromagnetic radiation; gases do not
C) Plasmas cannot produce magnetic fields, unlike gases
D) Plasmas can occur only in low density environments, like space
E) There is no difference; they are synonyms
23. If I tell you that a star is hotter than an F2 star but cooler than an A7 star, which of the
following might it be?
A) A3
B) B6
C) F0
D) G1
E) O8
24. Which of the following fuels is a source of fusion power in a high mass star near the
end of its life?
A) Hydrogen (only)
B) Helium (only)
C) Other elements (only)
D) Hydrogen and helium, but not other elements
E) Hydrogen, helium, and other elements
25. Which of the elements listed below is in the largest quantity in the composition of
most stars?
A) Helium B) Oxygen C) Carbon
D) Iron
E) Neon
26. If I had a hot, thick solid, liquid, or gas, the type of spectrum it would produce would
be a
A) Monochromatic spectrum, consisting of only one wavelength
B) Bright line spectrum, consisting of only a few wavelengths
C) Dark line spectrum, consisting of all except for a few wavelengths
D) Continuous spectrum, containing all wavelengths
E) Null or black spectrum, containing no wavelengths
27. During the protostar stage, a star gradually gets hotter and hotter. What is the source
of this heat?
A) Fusion of hydrogen to helium
B) Fusion of helium to carbon
C) Fusion of carbon to oxygen
D) Gravitational contraction; the star is shrinking and this is the source of heat
E) It isn’t really getting hotter, it is just gradually becoming more visible
28. Does the Sun rotate?
A) Yes, it all rotates uniformly at the same rate
B) Yes, and it all rotates the same direction, but it rotates faster at the equator than
the poles
C) Yes, though some of it rotates one way and some the other way
D) No
E) Whether the Sun rotates or not is not known.
29. What is at the core of a double shell-burning star?
A) Inert hydrogen, not doing anything
B) Hydrogen fusing to helium
C) Inert helium, not doing anything
D) Helium fusing to carbon and oxygen
E) Inert carbon and oxygen, not doing anything
30. Which of the following is not true about the core of the Sun?
A) It is at a higher temperature than the rest of the Sun
B) It is the only part of the Sun where nuclear fusion occurs
C) It is a plasma
D) The fraction of helium in this region has risen substantially since the Sun was
born
E) Heat is transported outwards by convection in this region
31. Certain stars emit extremely regular pulses of light, radio waves, or something
similar. What is the probable source of these extremely regular pulses?
A) A spinning neutron star
B) A pulsing white dwarf
C) A core helium burning star
D) A binary star system
E) LGM (little green men)
32. Betelgeuse is a cool but very luminous star. On the Hertzsprung-Russell diagram, it
can be found in the
A) Upper left B) Lower left C) Upper right D) Lower right E) Center
33. If a star is at a distance of 32.6 light years, what will its parallax be in arc-seconds?
A) 106
B) 0.00841 C) 10
D) 0.1
F) 0.01