Astr 222 Final Exam Study Questions
Short Answer Questions
The final exam will list EIGHT short answer questions; you must pick SEVEN of them to answer. Each
short answer should be a short paragraph or so in length, and they will
be worth 5 points each. They will be similar to the ones given below:
Also study the short answer questions
given on the midterms (both the real midterms and the practice midterms). One or two of
the short answer questions on the midterm WILL come from those lists.
- Describe how the appearance of a galaxy would
change (in terms of apparent magnitude, angular size, surface brightness, and
morphology) if we were to magically move it to higher and higher
redshift. You don't need to give quantitative numbers, but describe
qualitatively what is happening.
- Describe how the stellar populations in spiral
galaxies differ from those in ellipticals, and how we can study these
stellar populations when galaxies are too far away to see their
- In a cosmological context, what is meant by "the era of
- Write down the Friedmann equation, including all terms.
Describe qualitatively what role each term plays in terms of the shape
and expansion history of the Universe.
- Describe what we mean by the morphology-density relationship for galaxies, and explain why galaxies behave this way.
The final exam will list THREE essay
questions, taken from the list below. You must pick TWO of them to
answer, and they will be worth 15 points each.
Your essays should be ~ 2-3 blue book pages in length; essays much
shorter than that probably will not be giving enough detailed
explanation to get full credit.
- Describe the early history of the Universe from
- Describe (in detail) 3 pieces of evidence for
in the Universe (using evidence that we have discussed in class).
- Give plausible values for the cosmological
H0, Omega(Matter), Omega(Lambda). For each, describe two pieces of
evidence which supports
the value you've given.
- Why couldn't the dark matter be all baryonic --
matter" that just doesn't shine (say dark clouds of dust, for example).
Give several reasons.
- Why does large scale structure and galaxy clusters in the Universe grow differently under different cosmological models? Describe
the difference in how structure forms both between cold and hot dark
matter cosmologies, as well as in cold dark matter cosmologies with
different values for Omega(Matter) and Omega(Lambda). Explain how can
we contrain the value of Omega(Matter)
using observations of galaxy clusters and large scale structure.
- Describe how supernovae can be used to study
cosmology: the physics behind the test, the observational data
required, and the results of these studies.
- Describe three ways for getting the mass of a
galaxy cluster, and what data you would need in each case. Do these
methods give reasonably consistent answers? Why or why not?
- Describe the properties of spirals arms in disk
galaxies. Explain the winding problem and how density waves work to
solve that problem. Why would star formation occur preferentially in
- Describe the structure of the Milky Way Galaxy. Be
sure to talk about the properties and relative sizes of the different
components of the Galaxy. Where is the Sun's location in the Galaxy? A
sketch will probably be useful here!
- Describe the Great Debate. Make sure to explain and evaluate
the arguments on both sides -- whose evidence was flawed, and why? How
did Edwin Hubble resolve this issue?
- Describe how the merger of two spiral galaxies
could produce an elliptical. Describe the important differences between
spiral galaxies and elliptical galaxies (think about morphology,
kinematics, gas content, etc), and explain how a galaxy merger could
account for these differences.
There will be THREE calculation
problems listed on the final; you must complete all three. Each answer
will be worth 5 points. These problems will be similar to the ones
- A distant galaxy cluster has a velocity
km/s and a half-light radius of 120 arcminutes. It has a average
velocity of 8000 km/s. How far away is it? Use the virial theorem to
that the mass of the cluster is ~ 5Rsigma2/G. Calculate the
mass of the cluster.
- If you had a telescope that could detect
mB=22, what is the maximum distance a galaxy could be at if
you wanted to study its globular clusters (which have a typical
of LB ~ 6x105 Lsun)?
- You are studying two galaxies which have both
supernovae in them. The supernova in Galaxy 1 had a maximum brightness
of mB=12, while the one if Galaxy 2 had a maximum brightness
of mB=15.5. How much further is Galaxy 2 than Galaxy 1? You
do not need to know the absolute maximum magnitude of supernovae Ia to
- Show how the Friedman equation can be used to derive the mass
a flat universe without a cosmological constant. If H0=72
what is the density?