Download Discussion Activity #11a

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ASTR100
Nov. 14, 2005
Discussion Worksheet #11
Please choose the best answer. When you are finished, tear this top sheet off and hand it in. The
packet of MC questions below is yours to keep.
1. Which of the following statements about various stages of core nuclear burning (hydrogen,
helium, carbon, and so on) in a high-mass star is NOT true?
A. As each stage ends, the reactions that occurred in previous stages continue in shells around
the core.
B. Each successive stage creates an element with a higher atomic number and atomic mass
number.
C. As each stage ends, the core shrinks and heats further.
D. Each successive stage lasts for approximately the same amount of time.
2. Why can the fusion of carbon occur in intermediate- and high-mass stars but not in low-mass
stars?
A. It is because the cores of low-mass stars never get hot enough for carbon fusion.
B. It is because carbon fusion can occur only in the stars known as carbon stars.
C. It is because the cores of low-mass stars never contain significant amounts of carbon.
D. It is because only high-mass stars do fusion by the CNO cycle.
3.
A.
B.
C.
D.
A spinning neutron star has been observed at the center of a _________.
planetary nebula
red supergiant
supernova remnant
protostar
4. Mark the turnoff points on the H-R diagrams below with an arrow. Then put the clusters in
order from youngest to oldest:
(images for problem 5 from www.astronomynotes.com)