20070514

Astronomy clicker question: metal-rich stars

Astronomy 10, Spring Semester 2007
Cuesta College, San Luis Obispo, CA

Astronomy 10 learning goal Q11.5

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

[0.3 points.] Which type of stars is more abundant in "metals" (elements heavier than hydrogen and helium) in their outermost layers?
(A) Extremely old stars that formed a long time ago.
(B) Young stars that formed very recently.
(C) (Both (A) and (B) would have equal amounts of elements heavier than hydrogen and helium in their outer layers.)
(D) (Neither (A) nor (B), as there cannot be elements heavier than hydrogen and helium in the outer layers of stars.)

Correct answer: (B).

Extremely old stars that formed a long time ago would have mainly hydrogen in their outer layers (while their cores steadily produce metals through its supergiant phase), and after undergoing type II supernova explosions, the metals from the cores of these stars would be incorporated with hydrogen into next generation of younger stars. Thus metals are produced by previous generation stars to be inheirited by the next generation stars.

Student responses
Section 4136
(A) : 8 students
(B) : 10 students
(C) : 8 students
(D) : 9 students

Student responses
Section 5076
(A) : 4 students
(B) : 1 student
(C) : 6 students
(D) : 8 students

2 comments:

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

    Student responses
    Section 4160
    (A) : 14 students
    (B) : 7 students
    (C) : 1 student
    (D) : 7 students

    Section 5166
    (A) : 16 students
    (B) : 7 students
    (C) : 10 students
    (D) : 7 students

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

    Section 4160

    Instructor: "...thus those massive stars pollute the universe with their heavy elements, which forces the next generation of younger stars to make themselves out of hydrogen as well as these impurities."

    Student: "Bastards!"

    (Class giggles.)

    Instructor: "Exactly! But lucky for us, planets and life require these heavy elements. We can't be made out of only pure hydrogen."

    Well, that's the way it might have been said.

    ReplyDelete