Ay 124:  The Second Homework Assignment		Due on Monday, February 18
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1.  Why is it important to measure the LF and the IMF?  List all of the
    interesting astrophysical applications you can think of.  Sketch the
    steps towards the determination of these two functions, and describe 
    the potential problems and uncertainties.
						(About 2 typed pages worth.)


2.  Review at least one paper on: either the bimodal star formation, or on
    brown dwarfs, or on the Galactic center.
						(~ 1 - 2 typed pages worth.)


3.  A little computational problem:

    o  Take a look at the Scalo or Wielen luminosity function,
       and make an eyeball estimate of a best fitting log-normal
       distribution (i.e., parabola on the log-log plot); you will
       need the modal M(V), peak count, and sigma (width).

    o  Assume that the vertical distribution can be approximated
       by two exponentials, depending on M(V), as in Fig. 2 of 
       Bahcall & Soneira (1980); approximate it as a step function.

    o  Neglect the interstellar extinction, and the spheroid.

    o  Compute differential and integrated star counts, N(m) and A(m)
       towards the Galactic pole, down to m(V) = 28.

    o  Compare your results with those of Bahcall & Soneira (1980),
       and discuss the discrepancies.

	(If you think this is tough, try other directions, 
	 and do not neglect the extinction and the spheroid.)