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