ASTR220

Collisions in Space

(Spring 2003; Reynolds)

QUIZ #2

[10 points; 10^th April 2003]

Name:

Student Number:

Please read and sign the following honor pledge:

“I pledge on my honor that I have not given or received any unauthorized assistance on this quiz.”

signed

Instructions for this examination:

1. Answer all questions.

2. No electronic calculators of any kind are to be used

3. This is a closed-book quiz: no notes are allowed.

4. Please write your answers directly on this paper in the gaps after each question. Do not feel that you have to use all of the available space.

5. If you need more space than provided, write the continuation of your answer on a separate sheet of paper. Be sure to write your name and the question number on every additional sheet you use.

SECTION A (true/false questions – ½ point each)

1. The “hydrogen burning” in the Sun is fundamentally different to the “hydrogen burning” that occurs when one puts a flame to a balloon full of hydrogen on Earth.

a. True

b. False

2. The Sun generates its energy via the so-called proton-proton chain

a. True

b. False

SECTION B (multiple choice – 1 point each)

3. The photosphere of the Sun is:

a. The main site of energy generation in the Sun

b. The place where the Sun’s gases become transparent

c. The very outermost layer of the Sun’s gases

d. The main site of X-ray production in the Sun

4. The most direct information we have on the nuclear reactions in the Sun comes from

a. Neutrinos

b. Gamma-Rays

c. Normal light waves

d. X-rays

5. Suppose we measure the parallax (wobble) of a star to be 0.02 arc-seconds. The distance of that star from the Earth is then

a. 0.02 parsecs

b. 0.02 AU

c. 50 parsecs

d. 50 AU

6. The reason why massive stars explode (i.e. undergo a supernova) is

a. The core turns into iron, which is a very stable element and hence can provide no more energy output.

b. The core turns into iron, which is a very unstable element and hence explodes.

c. Conversion of hydrogen to helium gets out of control and causes the explosion.

d. Scientists don’t know.

SECTION C (short answer)

7. [2 points] Draw a Hertzsprung-Russell diagram, being sure to label the axes. Mark on the diagram the location of the Main Sequence, White Dwarfs, Red Giants and Supergiants.

8. [3 points] Briefly describe the main stages in the past and future life of the Sun. Aim for one sentence for each significant life-event experienced by the Sun.