- Binney & Merrifield 9.4
- 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.
- 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.
- A. Explain why this observation provides a constraint on the
- B. Identify the combination of these constants which is constrained.
- C. Assuming we are 8 kpc from the galactic center, what numerical
value for one of the Galactic constants can you extract?
- The Milky Way
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.)
- A. Compare and contrast the ELS and Searle & Zinn galaxy formation
- B. Give two distinct arguments against stochastic heating of the
thin disk as the sole origin of the thick disk.
- C. What is the main argument which suggests that the formation of
the halo and thick disk are disconnected?
- D. Describe two observations which support an accretion origin for
at least part of the halo.
- E. What is the single most important results which suggests a
dissipative origin for the thick disk?