TRUE/FALSE. Write 'T' if the statement is true and 'F' if the statement is false.
1) The upper limit to the mass of a white dwarf is 1.4 solar masses.
2) All pulsars are neutron stars, but not all neutron stars are pulsars.
3) There is no upper limit to the mass of a neutron star.
4) We can see most of the galaxy with visible light.
5) The Sun is located at the edge of the galaxy, approximately 50,000 light-years from the galactic center.
6) Almost all elements heavier than hydrogen and helium were made inside stars.
7) Most of the current star formation in the Milky Way occurs in spiral arms.
8) No galaxies are observed to have a blueshift.
9) The larger the value of Hubble's constant, the more rapid the expansion of the universe and hence the younger the universe.
10) Massive-star supernovae and white-dwarf supernovae work equally well as standard candles for measuring cosmic distances.
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
11) Degeneracy pressure is the source of the pressure that stops the crush of gravity in all the following except
A) a neutron star.
B) a very massive main-sequence star.
C) the central core of the Sun after hydrogen fusion ceases but before helium fusion begins.
D) a white dwarf.
E) a brown dwarf.
12) White dwarfs are so called because
A) it amplifies the contrast with red giants.
B) the are both very hot and very small.
C) they are the opposite of black holes.
D) they are supported by electron degeneracy pressure.
E) they are the end-products of small, low-mass stars.
13) A teaspoonful of white dwarf material on Earth would weigh
A) about the same as the Earth.
B) about the same as Mt. Everest.
C) the same as a teaspoonful of Earth-like material.
D) a few million tons.
E) a few tons.
14) Suppose a white dwarf is gaining mass because of accretion in a binary system. What happens if the mass someday reaches the 1.4-solar-mass limit?
A) The white dwarf, which is made mostly of carbon, suddenly becomes much hotter in temperature and therefore is able to begin fusing the carbon. This turns the white dwarf back into a star supported against gravity by ordinary pressure.
B) A white dwarf can never gain enough mass to reach the limit because a strong stellar wind prevents the material from reaching it in the first place.
C) The white dwarf immediately collapses into a black hole, disappearing from view.
D) The white dwarf undergoes a catastrophic collapse, leading to a type of supernova that is somewhat different from that which occurs in a massive star but is comparable in energy.
15) What kind of pressure supports a white dwarf?
A) radiation pressure
B) electron degeneracy pressure
C) thermal pressure
D) neutron degeneracy pressure
E) all of the above
16) What is the diameter of the disk of the Milky Way?
A) 1,000,000 light years
B) 1,000 light years
C) 100,000 light years
D) 10,000 light years
E) 100 light years
17) What kinds of objects lie in the halo of our galaxy?
A) open clusters
B) globular clusters
C) gas and dust
D) O and B stars
E) all of the above
18) Which of the following comprise the oldest members of the Milky Way?
A) Cepheid variables
B) O stars
C) globular clusters
D) red giant stars in spiral arms
E) the Sun and other solar mass stars
19) Approximately how far is the Sun from the center of the galaxy?
A) 2,800 light-years
B) 28 light-years
C) 280 light-years
D) 28,000 light-years
E) 28 million light-years
20) What produces the 21-cm line that we use to map out the Milky Way Galaxy?
A) helium
B) atomic hydrogen
C) molecular hydrogen
D) ionized hydrogen
E) carbon monoxide
21) The disk component of a spiral galaxy includes which of the following parts?
A) halo B) spiral arms D globular clusters
C) bulge D) all of the above
22) Why are Cepheid variables important?
A) Cepheids are pulsating variable stars, and their pulsation periods are directly related to their true luminosities. Hence, we can use Cepheids as "standard candles" for distance measurements.
B) Cepheids are a type of young galaxy that helps us understand how galaxies form.
C) Cepheid variables are stars that vary in brightness because they harbor a black hole.
D) Cepheids are supermassive stars that are on the verge of becoming supernovae and therefore allow us to choose candidates to watch if we hope to observe a supernova in the near future.
23) Why is the Hyades Cluster important for building up a catalog of the true luminosities of main-sequence stars?
A) It is an old globular cluster that has been around our galaxy for several billion years.
B) It is close enough to us that the distance to the cluster stars can be found by stellar parallax.
C) It is an extremely bright cluster.
D) It contains many Cepheid variables.
E) We have brightness measurements for the stars in the cluster over many decades, so we know how the stars vary in brightness.
24) What is the Tully-Fisher relation?
A) the longer the period of a galaxy's variable stars, the more luminous it is
B) the faster a spiral galaxy's rotation speed, the more luminous it is
C) the smaller a galaxy appears, the further away it is
D) the further away a galaxy is, the faster its recession velocity
E) the redder a galaxy's color, the further away it is
25) What is the most accurate way to determine the distance to a nearby galaxy?
A) using Cepheid variables
B) Hubble's law
C) radar ranging
D) the Tully-Fisher relation
E) stellar parallax
1) Answer: TRUE
2) Answer: TRUE
3) Answer: FALSE
4) Answer: FALSE
5) Answer: FALSE
6) Answer: TRUE
7) Answer: TRUE
8) Answer: FALSE
9) Answer: TRUE
10) Answer: FALSE
11) Answer: B
12) Answer: B
13) Answer: E
14) Answer: D
15) Answer: B
16) Answer: C
17) Answer: B
18) Answer: C
19) Answer: D
20) Answer: B
21) Answer: B
22) Answer: A
23) Answer: B
24) Answer: B
25) Answer: A