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Will ask questions
	The first question that you will be asked will be drawn
	from one of the following questions.  You may asked more
	than one question from this list.
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1. Describe at least 4 methods that have been used to measure
the masses of "black holes" in galactic nuclei, and discuss
their pros, cons, and error budgets.

2. It is commonly believed that 70% of the mass-energy in the
universe is in the form of "dark energy" or a cosmological constant.
Explain the observational and theoretical basis for this belief.
You may be asked to derive some relevant cosmological equations
to justify your assertions.

3. Describe the major processes which are believed to have made the
present-day power spectrum of density fluctuations differ, on scales
from 1kpc to 1Gpc, from the primordial (post-inflation) "Zeldovich"
n=1 powerlaw.

4. Draw a Hertzsprung-Russell diagram, with labelled Luminosity and
Temperature axes, and on this draw a main sequence (with some
stellar masses labelled), describe the main features of
the post-main sequence evolution of stars of different masses,
and their final states 10^{10} years after birth.

5. What is the temperature of the cosmic microwave background, and
what is the photon-to-baryon ratio?
Is the temperature of the cosmic neutrino background expected
to be the same or different?  Explain why as quantitatively as you can.

6.  What is the Schechter luminosity function for galaxies ?
Given a count N(mag) that extends very faint, how can one
derive the LF for galaxies at redshifts 1 to 3 ?


7. A sphere of gas of radius R has a temperature $T$. What is
its bolometric luminosity, if its optical depth for photons
of energy $kT$ is $\tau$. What would be its spectrum if the main 
source of opacity at all wavelengths is small dust grains.

8. How many photons per second are received by Keck from a 20th magnitude
object in the R band filter? Given the solar luminosity, how long of 
exposure HST needs to take at a Kuiper Belt object of 100km to detect 
a hundred photons?

9. Desribe various sources of opacity in stellar atmospheres.  What are the
dominant sources in main sequence O stars?  M stars?

10. Explain how supernovae of Type Ia have been used by Saul Perlmutter,
Adam Riess and their colleagues to determine that the universe is now
accelerating. One of the most important goals of recent HST supernovae
campaigns is to look back to the era when the Universe was not
accelerating. Explain why determining the rate of expansion at various
epochs is key to understanding the nature of dark energy.

10. What use is gravitational lensing other than a beautiful vindication of
the effects of General Relativity? Present some observations which
illustrate the astrophysical usefulness of this phenomenon.

11. The Chandrashekar mass limit is fundamental to astronomy.
     Derive the Chandrashekhar mass limit

12. On a plot of radius (y-axis) and mass (x-axis) locate
	the white dwarf sequence, the main sequence and the brown
	dwarfs. I will be looking for some accuracy in the drawing.
        Normalize to Msun and Radius of Jupiter.

13. Be prepared to compute the duration, depth and probability
    of a star (radius R) being occulted by planet (radius Rp)
    and semi-major axis, a.  Be prepared to give an example
    of such a system and what has been learnt from the observations.
       
14. What is the wavelength range and instruments (as many as you know)
    on Spitzer,Hubble, Chandra, XMM, Astro-E2 and Swift?

15. What is the most interesting colloquium you attended the past year?
    Summarize the results.