Astronomy final exam question: comparing relative potential habitability of Kepler-62e, Kepler-62f

Astronomy 210 Final Exam, spring semester 2013
Cuesta College, San Luis Obispo, CA

According to a NASA press release[*], the star Kepler-62 is a medium-mass main-sequence star somewhat similar to the sun, and:

Kepler-62 is home to two habitable zone worlds, Kepler-62f and Kepler-62e. Kepler-62f [orbiting farther out] is only 40 percent larger than Earth... Kepler-62e [orbiting closer in] is roughly 60 percent larger than Earth.

Determine which planet (62f or 62e) would be more likely to have an atmosphere with a moderate greenhouse effect and a moderate temperature for liquid oceans to be present. Explain using the properties of greenhouse gases and geological activity.

[*] http://www.nasa.gov/mission_pages/kepler/multimedia/images/kepler-62-diagram.html.

Solution and grading rubric:

• p = 20/20:
  Correct. Recognizes how (1) mass determines atmosphere thickness (more massive planet Kepler 62e would outgas more atmosphere, and better gravitationally retain this atmosphere); and how (2) distance from sun determines the temperature of an atmosphere (Kepler 62e being closer to its star would absorb and retain more heat). Thus Kepler 62e would be more susceptible to higher temperatures and more likely evaporate its oceans, while less mass and further out Kepler 62f would be more likely to have moderate temperatures for liquid oceans.
• r = 16/20:
  Nearly correct (explanation weak, unclear or only nearly complete); includes extraneous/tangential information; or has minor errors. One of two points (1)-(2) correct, other is problematic/incomplete. May argue that Kepler 62f would have an atmosphere that is too thin, and too little heat absorbed for moderate temperatures for liquid oceans, making Kepler 62e the more ideal candidate.
• t = 12/20:
  Contains right ideas, but discussion is unclear/incomplete or contains major errors. Both points (1)-(2) problematic/incomplete, or one point correct while other is missing.
• v = 8/20:
  Limited relevant discussion of supporting evidence of at least some merit, but in an inconsistent or unclear manner. At least understands factors that contribute to atmosphere density and greenhouse effect.
• x = 4/20:
  Implementation/application of ideas, but credit given for effort rather than merit. Discusses factors other than relevant to the greenhouse effect.
• y = 2/20:
  Irrelevant discussion/effectively blank.
• z = 0/20:
  Blank.

Grading distribution:
Section 30674
Exam code: finalnNz2
p: 4 students
r: 7 students
t: 8 students
v: 6 students
x: 1 student
y: 1 student
z: 0 students

Section 30676
Exam code: finals56G
p: 3 students
r: 7 students
t: 17 students
v: 9 students
x: 0 students
y: 1 student
z: 2 students

A sample "p" response (from student 0211):
Another sample "p" response (from student 6608):
A sample "y" response (from student 0426):
Another sample "y" response (from student 9251):

Astronomy final exam question: halo stars likely for life?

Astronomy 210 Final Exam, fall semester 2009
Cuesta College, San Luis Obispo, CA

Halo stars of the Milky Way would not be likely places to find life because halo stars:
(A) are metal-poor.
(B) are not massive enough.
(C) are not old enough.
(D) have too much dark matter.

Correct answer (highlight to unhide): (A)

Halo stars are the first generation of stars born in the Milky Way, and thus would be metal-poor, as well as their planets, which would then not have "metals" (any elements heavier than hydrogen, which would include carbon and oxygen).

Section 70160
(A) : 27 students
(B) : 4 students
(C) : 4 students
(D) : 6 students

Success level: 69% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.11

Astronomy final exam question: Pluto and Earth's moon switch

Astronomy 210 Final Exam, fall semester 2008
Cuesta College, San Luis Obispo, CA

[20 points.] Discuss how Pluto and how Earth's moon would each be classified by the International Astronomical Union if they were to exchange positions. (Consider them to be approximately the same mass.)

Solution and grading rubric:

• p = 20/20:
  Correct. Pluto would become a moon of Earth's, while the Earth's moon would orbit the sun directly (and not be a moon), retain its round shape (and thus not be solar system debris), but as it would neither clear out nor dominate the Kuiper belt anymore than Pluto did, it would now be classified as a
  dwarf planet, and not a planet. (May use dwarf planet synonymously with "planetoid" or "small planet.")
  
• r = 16/20:
  Nearly correct (explanation weak, unclear or only nearly complete); includes extraneous/tangential information; or has minor errors. One of the classifications is problematic, but the IAU classification scheme is systematically applied to both objects.
  
• t = 12/20:
  Contains right ideas, but discussion is unclear/incomplete or contains major errors. Some discussion of difference in lifetimes, but compounded/confounded with other factors. Problematic application of IAU classification scheme.
  
• v = 8/20: Limited relevant discussion of supporting evidence of at least some
  merit, but in an inconsistent or unclear manner. Uses criteria other than that defined by the IAU classification scheme.
  
• v = 8/20:
  Limited relevant discussion of supporting evidence of at least some merit, but in an inconsistent or unclear manner.
  
• x = 4/20:
  Implementation/application of ideas, but credit given for effort rather than merit.
  
• y = 2/20:
  Irrelevant discussion/effectively blank.
  
• z = 0/20:
  Blank.
  

Grading distribution:
Section 70158
p: 20 students
r: 17 students
t: 10 students
v: 15 students
x: 3 students
y: 3 students
z: 1 student

A sample "p" response (from student 0805):
An illustrated "p" response (from student 1616):
A "p" response (from student 0013) anthropomorphizing Pluto and Earth's moon:
A sample "v" response (from student 3825) speculating on the mind-boggling implications of this Pluto-Earth's moon switch:
A sample "x" response (from student 5588) equating Pluto and Earth's moon:
A sample "y" response (from student 6948):

Astronomy final exam question: life on massive main sequence star exoplanets

Astronomy 210 Final Exam, Fall Semester 2008
Cuesta College, San Luis Obispo, CA

[4.0 points.] Why are planets that orbit massive main sequence stars not thought to be good candidates for life to exist?
(A) Massive main sequence stars are too luminous.
(B) Massive main sequence stars have short lifetimes.
(C) These planets would be geologically dead.
(D) These planets would be too large.

Section 70160
(A) : 1 students
(B) : 27 students
(C) : 2 students
(D) : 0 students

Correct answer: (B)

Massive star have main sequence lifetimes on order of millions of years (or even less), much less than how biological life arose from chemical evolution arose on Earth (on order of billions of years), with the caveat that this process would take the same amount of time elsewhere.

"Difficulty level": 91% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.25

Astronomy clicker question: extrasolar planet orbits

Astronomy 10, Spring Semester 2008
Cuesta College, San Luis Obispo, CA

Astronomy 10 learning goal Q7.5

Students were asked the following clicker question (Classroom Performance System, einstruction.com) in the middle of their learning cycle:

[0.3 points.] How did "extrasolar" giant planets in small, eccentric orbits form?
(A) They were formed very close to their stars, in eccentric orbits.
(B) They were formed very far from their stars, in circular orbits, but their orbits were disrupted by collisions with other protoplanets, and spiraled inwards.
(C) They were formed very far from their stars, in circular orbits, but they lost angular momentum to the protoplanetary disk, and spiraled inwards.
(D) They were produced by material ejected from a collision between two stars.

Correct answer: not revealed yet (see discussion below).

Student responses
Section 4160
(A) : 0 students
(B) : 20 students
(C) : 4 students
(D) : 1 student

Section 5166
(A) : 11 students
(B) : 8 students
(C) : 7 students
(D) : 6 students

The students in section 4160 chose impacts on protoplanets (response (B)) over the correct response (C) of (gradual) angular momentum redistribution, after a discussion earlier in the same lecture about angular momentum transfer from the young Sun to its nebular disk. This prompted a refresher on this same subject immediately afterwards.

In section 5166, after showing the lack of consensus in their replies, students were asked to discuss their responses with each other before responding again, with a moderate shift towards the correct answer.

Student responses
Section 5166
(A) : 8 students
(B) : 8 students
(C) : 13 students
(D) : 3 students

Correct answer: (C)