Lecture Questions
Wednesday, November 19
- The "White Dwarf" Question
- A white dwarf is roughly:
- (a) The mass of the Sun and 10km in radius.
- (b) The mass of the Earth and 10km in radius.
- $(c) The mass of the Sun and the size of the Earth.
- (d) The mass of the Earth and the size of the Sun.
- (e) The mass of the Sun and 10R_sun in radius.
- (f) Several times the mass of the Sun and 100R_sun in radius.
- "Our Future" question
- Which of the following is likely to happen in our solar system in
the future? (More than one may be correct.)
- $(a) Red Giant.
- (b) Fusion of Carbon and Oxygen to heavier elements.
- $(c) Planetary Nebula.
- $(d) White Dwarf.
- (e) Nova.
- (f) Red Sox Win World Series.
- "Future Nova" question
- In which of the following star systems might it be possible to
observe a nova in the (possibly distant) future? (More than one may be
right.)
- (a) A white dwarf by itsef.
- $(b) A binary system with a white dwarf and a red giant.
- $(c) A binary system with two main sequence stars, one of mass 3 M_sun and one of mass 2 M_sun.
- (d) A binary system with two main sequence stars, one of mass 12 M_sun and one of mass 3 M_sun.
- $(e) A system where you have observed a previous nova.
- (f) A system where you have observed a Type Ia supernova.
- The "Type II" Question"
- In which of the following would you expect it possible to observe a
Type II (core collapse) Supernova in the future?
- $(a) A star forming region (e.g. Orion Nebula cluster)
- (b) A globular cluster (e.g. M13, 47 Tuc)
- $(c) The Virgo galaxy cluster
- (d) A galaxy that formed before the Cosmic Microwave Background was emitted.
- $(e) A galaxy that formed after the CMB was emitted, but more than 5 billion years ago.
- The "Type Ia/II Question
- You observe a Type Ia (thermonuclear) supernova from an unspecified
galaxy. Is it impossible, possible, or inevitable that you will later
(perhaps much later) observe a Type II supernova from that same galaxy?
- (a) Impossible
- $(b) Possible
- (c) Inevitable
What if that galaxy were just like the Milky Way?- (a) Impossible
- (b) Possible
- $(c) Inevitable
- The "Size Ranking" Question
- Rank these from smallest (in size) to biggest:
I. 0.6 M_sun White Dwarf
II. 1.2 M_sun White Dwarf
III. 2 M_sun Neutron Star
IV. 4 M_sun Black Hole
V. Fusing Core of the Sun
- (a) I, II, III, IV, V
- (b) V, I, II, III, IV
- (c) IV, III, I, II, V
- $(d) IV, III, II, I, V
- (e) IV, III, V, II, I
- "Starfire" Question
- In Charles Sheffield's novel Aftermath (the title mentioned
in class, Starfire, is actually the sequel), global disaster
results when one of the stars in the Alpha Centauri system goes
sueprnova. Astronomers in the novel are very surprised; why?
- (a) Alpha Centauri is 4 light-years away, so we should have had 4 years warning before the energy of the explosion reaches us. Astronomers were surprised that we didn't.
- $(b) Alpha Centauri is composed of two main-sequence stars of a mass similar to the Sun; stars of that mass will never explode in a core-collapse supernova.
- (c) Because they were clueless; they shouldn't have been surprised. One of Alpha Centauri's stars could have become a white dwarf and exploded in a Type Ia supernova.
- "Globbie" Question
- Stars in globular clusters have some heavy elements, but a lower
abundance of heavy elements than the Sun does. What does this tell us
about those stars in comparison to the Sun?
- (a) Stars in globular clusters are much lower mass than the Sun, because they do not have as many high-mass elements.
- (b) Stars in globular clusters are much older than the Sun.
- $(c) The gas that produced the Sun went through more generations of star formation than the gas that produced the stars in glubular clusters.
- (d) Stars in globular clusters come from the first generation of stars produced directly out of the material from the Big Bang.
- "O-Star" Question
- Where in the Milky Way would you expect to find a massive O-star?
- $(a) In the disk.
- (b) In the halo.
- (c) Either in the disk or in the halo.
Wednesday, December 3
- "Sun Black Hole" Question
- The Sun collapses and becomes a black hole (in flagrant violation of
our theroies of stellar evolution). What happens to the tides on Earth?
- (a) There would be almost no more tides.
- $(b) They would stay the same as the are now.
- (c) They would become much stronger (i.e. higher high tides, lower low tides).
- (d) Tidal forces would tear the Earth apart.
- "Mass of Stars" Question
- Given the differences between golbular and open clusters listed on
the previous slide, which component of the Milky Way has a greater total
mass of stars?
- (a) The Halo has more stars.
- (b) The Disk has more stars.
- $(c) We can draw no conclusion from this information.
- "Disk-Halo Color" Question
- Given the differences between globular and open clusters listed two
slices back, what can we say about the coor of the Disk stars versus the
color of Halo stars?
- (a) The Disk will tend to be redder than the Halo.
- $(b) The Disk will tend to be bluer than the Halo.
- (c) We can draw no conclusion from this information.