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
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.
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.
q 0.5
points for each of:
q Luminosity
and Temperature axes drawn correctly
q Approximately
correct numerical scales on axes
q Approximately
correct positioning of main sequence
q Approximately
correct placement of other types of stars
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.
q Main
points to cover are (0.5 pt for each, to max of 3 pts):
q Sun forms from collapsing gas cloud
q Nuclear fusion (hydrogen burning) starts in core
q Sun lives on main sequence for about 10 billion years
q Hydrogen then runs out and energy generation stops
q Core contracts and outer region of Sun puffs up. Sun becomes Red Giant
q Series of novae explosions eject outer layer of Red Giant (forms planetary nebula)
q Left with a white dwarf (dead core of the Sun)