Cuesta College, San Luis Obispo, CA
[20 points.] Discuss the evidence for the monolithic collapse model of the Milky Way (spherical gas cloud flattening into a disk). Support your answer using the orbit and metal content properties of halo stars versus disk stars.
Solution and grading rubric:
- p = 20/20:
Correct. Discusses evidence supporting the flattening of the Milky Way's shape by explaining how metal content increases for younger generations of stars, and observations that disk stars are metal-rich compared to the metal-poor halo stars above and below the disk.
- r = 16/20:
Nearly correct (explanation weak, unclear or only nearly complete); includes extraneous/tangential information; or has minor errors.
- t = 12/20:
Contains right ideas, but discussion is unclear/incomplete or contains major errors.
- v = 8/20:
Limited relevant discussion of supporting evidence of at least some merit, but in an inconsistent or unclear manner. At least some discussion related to the monolothic collapse model.
- x = 4/20:
Implementation/application of ideas, but credit given for effort rather than merit. Discussion unrelated to the monolithic collapse model.
y = 2/20: Irrelevant discussion/effectively blank.
- y = 2/20:
Irrelevant discussion/effectively blank.
- z = 0/20:
p: 17 students
r: 8 students
t: 4 students
v: 6 students
x: 3 students
y: 3 students
z: 0 students
A sample "p" response (from student 1991):