Study Guide for Astronomy & Astrophysics I Exam 2 (Fall 2018)

1. Make sure you understand protostellar cloud collapse (Jeans criterion and conditions for collapse, free-fall time for collapse, reason for and relation for increase of rotation and magnetic field)
2. Understand the effects of interstellar reddening by dust, the differences in and reasons for colors of reflection and emission nebulae.
3. Be familiar with tidal forces, how they arise, how they act on a body in both the external frame and the frame of the body. Know the various observable effects caused by tidal forces.
4. Be able to say what the selection effects are for the leading two extrasolar planet detection methods (radial velocity method and the transit method). Understand what is measured in the radial velocity method, and why stars wobble.
5. Know the observed characteristics of our solar system that any theory of planet formation have to account for. Be able to say how the current theory addresses these characteristics.
6. Review the Hill radius, which gives the range of radii over which accretion through gravitational attraction is possible.
7. Review the discussion of equilibrium temperature for a planet, and how to use it to get the rms velocity of any gas species. Know how to calculate the escape velocity from the surface of a planet, and how to compare rms vs. escape velocity to determine if a planet can hold on to various gas species.