Time: 2:50 pm, Friday, January 20, 2012<br>
Test 1, 26 January 2012<br>
Astronomy 123</br>
Winter 2012<br>
<p>
Material: Topic 1 (drawn from parts of Chapters 23-27), 
Topic 2 (Chapter 23 and part of 24) (as far get in Topic 2) 
<p>
<a href="astr123_x1.pdf">Old Test</a>
<p>
INTRODUCTION<p>
<ul>
<li>Cosmology: What is the definition of cosmology? Is cosmology science?
<li>Contrast Universe and universe. Why does the fact
that we have observations of only 1 universe hinder theory? What is meant by
<i>multiverse</i>?
<li>What makes a <i>model</i> scientific? Contrast science and philosophy.
Is cosmology a science or is it philosophy? Defend your position.
<li>Basic Observations of cosmology (which drive the Big Bang Theory):
<ul><li>The Universe is expanding as implied by Hubble's Law
(24.3). Who initially discovered Hubble's Law?  .
What is the <i>naive</i> interpretation
of Hubble's Law? What is the Principle of Mediocrity and how does it 
contribute to our
interpretation of Hubble's Law? What is the current interpreration 
accepted by most astronomers for Hubble's Law? What is z? What is meant
by redshift? How are redshifts of galaxies determined?
<li>Cosmic Microwave Background Radiation (CMBR), What is it? When was it 
formed? What are we observing when we see the
CMBR? What are the properties of the CMBR? (26.7) (What is its temperature?
Are there deviations from the mean temperature of the CMBR, if so, what are
they and how are they interpreted?) What is horizon problem?
(27.4) What is COBE? What is WMAP? 
<li>Chemical composition of the normal matter in the 
Universe is roughly 90 % hydrogen and ~ 10 %
helium (everyting else heavier than helium is referred to as a <i>metal</i>
and makes-up only a small part of the Universe). How is the  
chemical composition of the Universe used as a piece of evidence 
which strongly supports the 
Big Bang theory. 
<li>What is the
make-up of the overall Universe? What is dark matter? What is normal matter?
What is dark energy? 
Who first proposed the idea of some sort of dark energy and why?
What fraction of the Universe is normal matter?
</ul>
Cosmological Principles:<ul>
<li>What is the Principle of Mediocrity? 
<li>What is the Copernican Revolution? What is the significance of  
annual trigonometric parallax for the Copernican Revolution?(pp 27-28).
Explain how Hubble's 
Law may be explained through uniform expansion of the Universe.
<li>Are we at the Center of the Galaxy? Describe how Herschel and 
Kapteyn, and Shapley (23.2) attempted to find our location in the Galaxy 
and the size of the Galaxy. What did Herschel, Kapteyn, and Shapley conclude
about the location of the Sun in the Milky Way galaxy? Who was correct? 
Why did the ones who were in error reach their erroneous conclussions (talk
about dust, what is dust?)? How do we currently study the structure of the
Galaxy? What
is the location of the Sun and the true shape of the Milky Way galaxy?
<li>Cosmological Principle (26.1), what is it? What is meant by 
the terms homogeneity
and isotropy? (The Universe is clearly not bland and uniform on all 
scales, so why can homogeneity and isotropy of the Universe be useful 
assumptions?) 
In the Cosmological Principle is the Universe allowed to evolve in time? Could
it be unchanging in time under the Cosmological Principle? What is a nice
example that our Universe is homogeneous and isotropic?
<li>Perfect Cosmological Principle, what is it? It is not currently used by
astronomers when they model the Universe. What are some reasons why
the Perfect Cosmological Principle is not in favor? What is the Cosmological
Constant? Why did Einstern propose the Cosmological Constant? 
Why did Einstein withdraw his 
suggestion of a Cosmological Constant? 
<li>Anthropic Principle, What is the Anthropic Principle? 
Does Jim like the Anthropic Principle? Why does
Jim like (or dislike) the Anthropic Principle?
</ul>
<li>Describe the <i>Big Bang Theory</i>.
Upon what observations is the Big Bang Theory based? Is the Big Bang on 
firm observational footing?
</ul>
Milky Way Galaxy (Chapter 23 and Chapter 24, Hubble galaxy types, 
and Hubble Tuning Fork diagram.
<ul>
<li>Milky Way Galaxy:
<ul>
<li>What is the Hubble classification of the Milky Way galaxy?
<li>Briefly describe the apparance of the Milky Way galaxy. What are the
three primary regions of the Milky Way galaxy? What are the properties of
these regions? How large are they? What are their stellar populations?
Which contains the largest amount of mass? ... ? What are the overall 
properties of the Milky Way galaxy? 
<li>A black hole lives in the center of the Milky Way galaxy. What is a 
black hole? What are the properties of nonrotating black holes
(Schwarzschild black holes) and rotating black holes (Kerr black holes). 
What is the Penrose mechanism? What is Cosmic Censorship?
<li>What are the properties of the black hole in the center of the
Milky Way galaxy? What are Event Horizon, singularity,
Schwarzschild radius, static limit, ergosphere? 
What is the escape speed from a black hole? 
<li>What are the properties of the black hole at the center of our Galaxy?
What are 
S2 and S6? What is Sgr A? Where is Sgr A? What are tidal forces?
<li>What are Population I stars? What are Population II stars? Where are 
each found?
<li>How is the structure of the Milky Way galaxy determined? What objects are
used to study the structure of the Milky Way galaxy? Why are OB stars, H I 
regions, H II regions, Giant Molecular Clouds used to study the spiral arms
of our Galaxy? What is meant by H I? by H II? 
<li>What are galactic rotation curves (what kinds of rotation curves did I 
discuss in class)?  How are
rotation curves found in the region outside of the visible disk of our
Galaxy, that is, outside of where we find stars and star forming regions
(OB star, H II regions, Giant Molecular Clouds)? How far do rotation curves
extend beyond the visible disk of our Galaxy? Describe how rotation curves
are used to deduce the masses of spiral galaxies.
(Note--how fast does the Sun move in its orbit about the center
of the Milky Way galaxy? How large is the orbit of the Sun about the center
of the Milky Way galaxy?) 
<li>What is the significance of the fact that most 
rotation curves are nearly flat at large distances from the centers of the
gaalxies (the galaxy spins at nearly the same speed
at large distances as at small distances from its center)? 
<li>How do the mass
estimates from rotation curve affect the question of the amount of Dark Matter
in our Galaxy?
<li>What are MACHOs? Where are MACHOs found? How are MACHOs detected? (What is
gravitational lensing?) What fraction of the Dark Matter is contained in
MACHOs?
</ul>
<ul>
<li>Sketch the Hubble Tuning Fork diagram, be sure to include schematic
representations of ellipticals, spirals, barred spirals, S0s & SB0s
(lenticulars), and Irregulars, By schmeatic, I mean indicate the flattening of
ellipticals, bulge sizes, and the tightness of the winding of spiral arms.
Hubble Galaxy Classification scheme (24.1)
<li>Describe Elliptical, Spiral, Barred Spiral, SBO, S0, and Irregulars.
What are Lenticulars? What the differences between Sa, Sb, and Sc galaxies,
E0 to E7 galaxies, Irr I and Irr II galaxies.
<li>Sketch the Hubble Tuning fork diagram. Describe how the general properties
of galaxies vary along the diagram (consider gas and dust, stellar populations,
Pop I and Pop II stars, star formation, ...)
<li>Is the Hubble Tuning Fork diagram an evolutionary sequence? (Do galaxies
evolve from one Hubble class to another?)
<li>What kinds of galactic collisions occur? What are the results of collisions
between similar disk galaxies, galaxies of greatly differing masses? 
Are collisions between aglaxies rare? 
What role do galactic colliions
play in galaxy evolution? What are Supergiant Ellipticals? Where do they 
arise? Describe the interactions suffered (and to be suffered) by the 
Milky Way Galaxy. Describe the evolution and apperance of the Antennae, 
Cartwheel, and Mice galaxies.
<li>What is the extragalacitc distance ladder? What is the Tully-Fisher
method (how does it work)? How do Cepheid variables fit into the 
extragalctic distance ladder? What are the most important 
ways to determine distances to distant objects?
<li>Describe how objects cluster in the Universe. Describe the properties of
clusters of galaxies (such as Virgo and Coma). Why are there no spirals found
near the centers of rich clusters of galaxies? What are cD galaxies? Why are
supergiant Elliptical galaxies often times found near the centers of rich 
clusters of galaxies? How were observations of galaxy clusters used to 
detect Dark Matter? Who was the first astronomer to suggest the existence
of Dark Matter? (What is meant by Dark Matter?)
<li>What is the look-back time?`The look-back time, distances to objects can
be misleading, why? What is a more well-defined way to describe the <i>location
</i> of distant objects in the Universe?
<li>What are voids, filaments, and the Sloan Great Wall? How were these 
features detected? Do these observed structures obviate the
Cosmological Principle as a viable asuumption for the nature of the
Universe? Why or why not. 
</ul>