Physics 5
Introduction to Astronomy

H. E. Smith                                                                                                       Spring 2007

Quiz 4 Monday 4/30/07

Physics 5 – Spring Quarter 2007

Prof. Smith

Answer Key

 

To answer the following questions, refer to the labels (a) through (e) on the H--R diagram sketch. [Note that choice (a) refers to the entire main sequence, while (c) and (d) refer to only small parts of the main sequence. If choices (c) or (d) offer better answers to the question than (a), use the best choice.]

 

1. Which group represents stars that are cool and dim?                                             A    B    C    D    E

2. Which group represents stars of the largest radii?                                                  A    B    C    D    E

3. Which group represents the most common type of stars?                                      A    B    C    D    E

4. Which group represents stars fusing hydrogen in their cores?                               A    B    C    D    E

5. Which group represents stars that are extremely bright and emit most                  A    B    C    D    E

    of their radiation as ultraviolet light?

 

6. The overall result of the proton-proton chain is:

A. 6 H becomes 2 He + energy.

B. 4 H becomes 1 He + energy.

C. p + p becomes 2 H + energy.

D. 2 H  + p becomes 1 He + energy.

 

7. What are neutrinos? What was the solar neutrino problem, and why do we think it has now been solved?

 

Neutrinos are subatomic particles produced in nuclear reactions. They move at nearly the speed of light and almost never interact with matter. Detectors on Earth found only about 1/3 of the neutrinos predicted by models of nuclear fusion in the Sun. This disagreement between theory and data was called "the solar neutrino problem." Today, we think we have solved the problem and that the electron neutrinos we were measuring had changed into other kinds of neutrinos. Recent experiments support this idea by showing that neutrinos can change their type. Other experiments are showing that the total number of neutrinos of all types is about what the models for fusion in the Sun predict, indicating that the problem is solved.