Astronomy 100
Section 2, Fall 2008
Homework I
Due MONDAY, November 10
On your scantron fill out your NAME, STUDENT
NUMBER, and NETWORK ID both in writing and in the
bubbles. In addition, fill out "FORM I."
1. The primary distances to the stars are found by
a) sending spacecraft to them
b) radar
c) how fast they move
d) their colors
e) parallax
2. The parallax of a star is 0.01 seconds of arc. What is its
distance?
a) .01 pc b) 1 pc c) 10 pc d) 100 pc e) 1000 pc
3. What is the color of a star with a temperature of 3000 K?
a) ultraviolet b) blue-white c) white d) yellow e)
red
4. What characterizes the spectrum of an A star?
a) titanium oxide
b) strong hydrogen
c) ionized calcium
d) ionized helium
e) molybdenum
5. What characterizes the spectrum of an M star?
a) titanium oxide
b) strong hydrogen
c) ionized calcium
d) argon
e) molybdenum
6. Of those spectral classes below, the hottest is
a) F b) G c) M d) B e) A
7. The Sun has what absolute magnitude and is of what spectral
class?
a) +10, K5
b) +15, A3
c) +5, G2
d) +3, M2
e) +12, B5
8. A class F dwarf star is typically made mostly of
a) fluorine
b) calcium
c) iron
d) helium
e) hydrogen
9. The standard spectral sequence is a result of
a) different stellar temperatures
b) differences in the amounts of hydrogen
c) differences in the amounts of helium
d) differences in the amounts of metal atoms
e) differences in the radii, hence densities, of the stars
10. The most luminous dwarf stars below are of class
a) O b) B c) G d) K e) M
11. The most common stars are
a) O dwarfs
b) M giants
c) K giants
d) white dwarfs
e) M, L, and T dwarfs
12. White dwarfs are typically about the size of
a) Champaign-Urbana
b) Chicago
c) Earth
d) the Sun
e) the inner planetary system
13. We know that supergiants are really larger than giants because
supergiants
a) move slower than giants through space as they are more
affected by gravity
b) are brighter than giants that have the same
temperatures
c) are hotter than giants that have the same luminosities
d) have destroyed their planetary systems whereas giants have
not
e) rotate slower than giants
14. Stellar masses are found from
a) variable stars
b) double stars
c) star clusters
d) planets in orbit around other stars
e) their neutrino emission
15. As you go down the main sequence from class A, stellar
masses
a) stay the same
b) decrease
c) increase
d) increase then decrease
e) decrease then increase
16. What is the minimum mass for a star that will run full hydrogen
fusion (in solar units)?
a) .001 b) 0.01 c) 0.08 d) 0.22 e) 0.53
17. The masses of white dwarfs are similar to that of
a) Champaign-Urbana
b) Chicago
c) Earth
d) the Sun
e) Jupiter
18. The coolest and brightest M supergiants are about at big as the
orbit of
a) Venus
b) Earth
c) Mars
d) Jupiter or Saturn
e) Pluto
19. Open clusters are found in the
a) Milky Way (the disk of our Galaxy)
b) Galaxy's halo
c) Galaxy's nucleus
d) Solar System
e) Alpha Centauri system
20. Brown dwarfs are
a) stars below the proton-proton chain mass cutoff
b) planetary satellites
c) supermassive stars
d) large interstellar dust grains
e) earth-like planets
21. The spectra of class T stars are characterized by
a) methane
b) ammonia
c) hydrogen
d) titanium oxide
e) nothing
22. Globular clusters are
a) found in the Galaxy's halo
b) much more massive than open clusters
c) are the oldest objects known
d) are much rarer than open clusters
e) all of the above
23. Old star clusters are missing
a) their lower main sequences
b) their upper main sequences
c) their giant branches
d) their white dwarfs
e) nothing
24. How old are the oldest star clusters in billions of years?
a) 0.5 b) 1 c) 3 d) 12 e) 30
25. The classic case of a white dwarf is the companion to
a) the Sun
b) Jupiter
c) Deneb
d) Sirius
e) Alpha Centauri