Cuesta College, San Luis Obispo, CA
[20 points.] Discuss what observations tell you that a star is metal-poor, and whether this is an old or young star, using the properties and evolution of stars in your explanation.
Solution and grading rubric:
- p = 20/20:
Correct. Discusses (a) how observations of absorption spectra classify stars as metal-poor, and (b) how production of metals in cores of massive and medium-mass stars is dispersed via type II/type Ia supernovae to be incorporated into the outer layers of subsequent generation stars.
- r = 16/20:
Nearly correct (explanation weak, unclear or only nearly complete); includes extraneous/tangential information; or has minor errors. One topic is complete/correct, other other is problematic.
- t = 12/20:
Contains right ideas, but discussion is unclear/incomplete or contains major errors. Only one of two discussion topics is complete and correct, the other is missing or has serious errors (typically spectroscopy); or both topics have minor errors.
- v = 8/20:
Limited relevant discussion of supporting evidence of at least some merit, but in an inconsistent or unclear manner. Discusses metal-poor stars as being old, but with conceptual errors; no discussion on spectroscopy.
- x = 4/20:
Implementation/application of ideas, but credit given for effort rather than merit. May discuss how metals are used to fuel a star; less metals would then indicate an older star that has used up all its metals.
- y = 2/20:
Irrelevant discussion/effectively blank.
- z = 0/20:
p: 5 students
r: 6 students
t: 23 students
v: 14 students
x: 22 students
y: 1 student
z: 0 students
A sample "p" response (from student 0711):
A sample "t" response (from student 1990):
Another sample "t" response (from student 3259):
A sample "x" response (from student 7027):