Modern Astronomy Spring 2004
Exam 4
This is a closed book exam, but calculators are allowed.
1. Which of the
following types of objects are found mostly in the arms of spiral galaxies?
a. O and B stars
b.
solar type stars
c.
pulsars
d.
dark matter
e.
globular clusters
2. Which of the
following objects are found in mostly in galactic halos?
a.
O and B stars
b.
solar type stars
c.
pulsars
d.
dark matter
e. globular clusters
3. A galaxy has a
measured red shift z = 0.075. What is its distance?
a.
0.075 Mpc
b.
5 Mpc
c.
75 Mpc
d. 300 Mpc
e.
750 Mpc
4. What
observational evidence supports the model that quasars have sizes less than one
parsec?
a.
large luminosity
b. rapid [hourly- weekly] time variations
c.
central location in a galaxy
d.
large distances
e.
energetic jets
5. Which of the following
is the most massive part of a galaxy?
a. The dark matter component
b.
The halo component
c.
The spiral arm component
d.
The massive black hole at the center
e.
The gas and dust in the disk
6. The most
compelling evidence for dark matter in galaxies is
a.
tidal interaction, causing massive black holes
b.
the presence of spiral arms which don’t ‘wind up’
c.
the halo of globular clusters centered on the core
d. the flat rotation curve at
large distance from the core
e.
The recent detection of WIMPS
7. Which statement
is incorrect concerning the Local
Group (LG) of galaxies?
a.
The LG contains the Milky Way galaxy
b.
The LG contains the large and small Magellanic Cloud galaxies
c.
The size of the LG is about 1 - 2 Mpc
d.
The number of galaxies in the LG is about 35-50
e. The LG is a rich cluster of
galaxies
8. Suppose the
Hubble constant were found to be 35 km/s/Mpc instead of 70 km/s/Mpc. How would
this affect our estimate of the age of the Universe?
a. It would double the present
estimate
b.
It would halve the present estimate
c.
It would increase the estimate 4 times
d.
It would decrease the estimate by 4 times
e.
It would not affect the age estimate
9. Which of the
following observations is not consistent with the Steady State model?
a.
Large-scale isotropy of galaxy distributions
b.
Large-scale homogeneity of galaxy distributions
c.
The Hubble expansion of the Universe
d.
The detection of dark matter
e. The cosmic background
radiation
10. Only one of the
observations listed below is consistent with the Steady State model. Which one?
a.
25% Helium abundance
b. Hubble expansion
c.
Evolution of galaxies at high redshift
d.
Cosmic background radiation
e.
The ‘age of quasars’ at near redshift 2
11. A galaxy with a central bar and very loose
spiral arms would be classified as Hubble type
a.
E7
b.
Sa
c.
Sc
d.
SBa
e. SBc
12. If the interior
angles of a very large triangle could
be measured and were found to be greater than 180°, what could one deduce about the fate of the Universe?
a.
Observed expansion would be ruled out
b. Expansion would stop,
followed by contraction
c.
Expansion would slow to a stop after an infinite time period
d.
Expansion would never stop
e.
Universe would oscillate with a period of 1 billion yrs
13. The center of the
Big Bang occurred
a.
Close to the Virgo cluster center
b.
In a ‘void’ the ‘Great Wall’ supercluster
c.
At the center of mass of the Universe
d.
In direction of the most distant quasars
e. Everywhere
14. What produced the radiation we see as the
cosmic background radiation?
a.
The oldest massive stars which became supernovae
b. Hot hydrogen gas
c.
Gamma-ray bursters
d.
Clumps of supermassive black holes
e.
Dark matter left over from the explosion
15. The age of the
Universe is closest to
a.
5 billion yr
b. 13 billion yr
c.
30 billion yr
d.
100 billion yr
e.
infinite [no age]
16. What key
observation was made in the 1920’s by Hubble that proved the existence of
galaxies other than the Milky Way galaxy?
a. Cepheid variable periods in
nebulae
b.
Fisher-Tully line widths
c.
Rotation curves in spiral arms
d.
Distribution of globular clusters
e.
Detection of spiral arms
17. The Fisher-Tully
relationship is between a galaxy’s
a. 21 cm line width and
luminosity
b.
Width of spiral arms and brightness
c.
Mass and central black hole size
d.
Overall size and mass
e.
Shape and luminosity
18. Which of the
following would not be classified as
a type of active galaxy?
a.
Seyfert galaxy
b.
Quasar
c.
BL Lac object
d.
Radio galaxy
e. RR Lyrae object
19. Which of the
following would not be characteristic
of a quasar?
a.
Appears star-like in a telescope
b. Has spectral lines of
unknown origin
c.
Has very high luminosity, comparable to entire galaxy
d.
Found at the center of a galaxy
e.
Associated with supermassive black hole
20. If an active galaxy is viewed at angle 90° to the rotation axis of the black hole,
what might one see?
a.
quasar
b.
BL Lac object
c. radio galaxy
d.
jets pointed straight at the observer
e.
nothing – must view head-on
21. The ‘Eddington limit’ is a relation between
a.
The maximum luminosity of an object with a given radius
b.
The minimum luminosity of an object with a given radius
c.
The maximum mass of an object with given luminosity
d. The minimum mass of an
object with given luminosity
e.
The maximum redshift of an object with a given diameter
22. Gamma Ray
Bursters (GRB’s) have recently been found to be
a.
Nova associated with white dwarfs in binaries
b.
In the disk of the galaxy
c.
In the halo of the galaxy
d.
In nearby galaxies in the local group
e. In distant galaxies
23. Which statement
is correct
regarding the discovery of the cosmic background radiation?
a. It was discovered
accidentally
b.
If was discovered by Hubble space telescope in deep field images
c.
It was discovered by Georges LeMaitre and George Gamow
d.
It was discovered by the first ultraviolet satellite observatory
e.
It was discovered after Einstein predicted its existence in 1916.
24. Since the night
sky is dark, what important cosmological conclusion can be made?
a.
Stars must be very far away
b.
The Sun is on the other side of the Earth
c.
There is a lot of dust in the Universe between stars and galaxies
d.
The Universe will eventually contract
e.
The Universe cannot be infinitely old
25. Galaxy A has a
redshift z = 0. 1 while galaxy B has a red shift z = 0.01. What statement is
correct about the distances to A and B?
a.
Galaxy A is 10x closer than galaxy B
b. Galaxy A is 10x farther
than galaxy B
c.
Galaxy A is moving faster than galaxy B but its distance is
unknown
d.
Galaxy A is moving slower than galaxy B but its distance is
unknown
e.
Neither galaxy’s distance can be known without knowing the
parallax
Equations and constants
H = 70 km/s/Mpc c= 300,000
km/s
Redshift z = V/c
Hubble’s law: V= Hd or d = cz/H