20090504

Astronomy midterm question: type Ia supernova sun?

Astronomy 210 Midterm 2, spring semester 2009
Cuesta College, San Luis Obispo, CA

Decide whether the sun will ever become a type Ia supernova[*]. If so, then specifically discuss how this process will occur. If not, then specifically discuss why this process cannot occur. Explain using the properties and evolution of stars.

[*] Jim Meddick, Monty, NEA Distributors (24 October 2003).

Solution and grading rubric:
  • p:
    Correct. A type Ia supernova is when a white dwarf has taken hydrogen from a binary companion star quickly enough to undergo runaway explosive fusion, destroying itself in the process. The sun is a medium-mass main sequence star that will eventually become a white dwarf, but with no binary companion star to take hydrogen from, it will never become a type Ia supernova.
  • r:
    Nearly correct (explanation weak, unclear or only nearly complete); includes extraneous/tangential information; or has minor errors. At least recognizes that an external source of hydrogen/energy is required for the white dwarf endstage of a medium-mass star like the sun to undergo a type Ia supernova.
  • t:
    Contains right ideas, but discussion is unclear/incomplete or contains major errors. Explains how the sun will eventually become a white dwarf, or makes the case for/against a type II supernova explosion.
  • v:
    Limited relevant discussion of supporting evidence of at least some merit, but in an inconsistent or unclear manner.
  • x:
    Implementation/application of ideas, but credit given for effort rather than merit.
  • y:
    Irrelevant discussion/effectively blank.
  • z:
    Blank.
Grading distribution:
Section 30674
p: 8 students
r: 6 students
t: 10 students
v: 7 students
x: 1 student
y: 1 student
z: 0 students

A sample "p" response (from student 0528): A sample "r" response (from student 1228): A sample "t" response (from student 7552):

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