ASTR 620
Problem Set 3
Due in class Wednesday 22 October 2003

  1. Binney & Merrifield 9.4

  2. Elliptical Galaxies

    We have used the exponential disk formula to describe the surface brightness profiles of spiral galaxies. For giant elliptical galaxies (and the bulge components of many spirals), the most commonly employed formula is the de Vaucouleurs R1/4 Law:

    I(r) = Iee-7.67[(r/Re)1/4-1]
    Give the total luminosity and the central surface brightess in terms of Ie and Re.

  3. Proper Motion of Sgr A*

    The radio source Sgr A* associated with the black hole at the center of the Galaxy is observed with the VLBI technique to have a proper motion of 6 milliarcseconds per year.

  4. The Milky Way

    Refer to Majewski (1993) ARA&A, 31, 575 to answer the following questions. Restrict yourself to no more than 10 lines per answer. Be sure to include relevant references. (References do not count against the line limit.)