ASTRONOMY 402T – Spring 2018
Problems for Tutorial Week #6

PART A

1. a) Enumerate the possible ways a nebula can have a net gain or loss in energy.

b) What processes can shuffle energy around in the nebula but not lead to a net energy loss.

2. In the 1940’s it was noticed that for H II regions in the spiral galaxy M33, the strengths of the [O III] λλ 4959, 5007 lines relative to Hβ increased as the distance of the H II region from the center of M33 increased. In addition, the nebular temperature likewise increased with increasing distance. We now know that the abundance of metals in a spiral galaxy generally decreases with distance from the center. How does this explain what was seen in M33? Be specific and as quantitative as possible.

PART B

Do the PN Gallery “Emission Lines and Central Star Temperature” exercise:

http://web.williams.edu/Astronomy/research/PN/nebulae/exercise1.php

 PART C

ESA Exercise: Distance to the Cat’s Eye Nebula