20160608

Astronomy final exam question: atoms in our bodies produced by red dwarfs?

Astronomy 210 Final Exam, spring semester 2016
Cuesta College, San Luis Obispo, CA

An astronomy question on an online discussion board[*] was asked:
Is it possible that any of the atoms in our bodies were made by red dwarfs?
Discuss why none of the atoms in our bodies could have been made by red dwarfs. Explain using the properties and evolution of stars.

[*] answers.yahoo.com/question/index?qid=20160503125038AAorV4v.

Solution and grading rubric:
  • p:
    Correct. Understands that atoms in our bodies were created by a previous generation of massive and medium-mass stars that exploded as type II or type Ia supernovae, which were capable of producing metals and scattering these atoms to be subsequently incorporated into the formation of our solar system and our bodies. Discusses how none of the atoms in our bodies can have been made by red dwarfs using at least one of the following or similar arguments:
    1. red dwarfs are incapable of metal formation (undergoing post-hydrogen fusion, or type II or type Ia supernova); or
    2. no red dwarfs have ever died yet (and thus they cannot contribute non-metals to us by some unforseen process that would occur in the far future).
  • r:
    Nearly correct (explanation weak, unclear or only nearly complete); includes extraneous/tangential information; or has minor errors.
  • t:
    Contains right ideas, but discussion is unclear/incomplete or contains major errors. Typically argues how younger, shorter-lived stars would have inherited their metals from earlier generations of stars undergoing type II or type Ia supernovae.
  • v:
    Limited relevant discussion of supporting evidence of at least some merit, but in an inconsistent or unclear manner. Garbled discussion of properties and evolution of stars.
  • x:
    Implementation/application of ideas, but credit given for effort rather than merit. Discussion other than that of the properties and evolution of stars.
  • y:
    Irrelevant discussion/effectively blank.
  • z:
    Blank.
Grading distribution:
Section 30674
Exam code: finalNKPd
p: 6 students
r: 0 students
t: 4 students
v: 3 students
x: 1 student
y: 0 students
z: 0 students

Section 30676
Exam code: finalSre6
p: 19 students
r: 1 student
t: 4 students
v: 5 students
x: 4 students
y: 8 students
z: 0 students

A sample "p" response (from student 1333):

Another sample "p" response (from student 8041):

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