Version C

Write your name at the top of this quiz as well as on your answer sheet, and hand them both in at the end of the quiz. WRITE YOUR VERSION ON YOUR ANSWER SHEET. Feel free to write or draw on the quiz.

SELECT THE BEST ANSWER TO EACH PROBLEM.

1. The Sun is a yellow star, Proxima Cen has a reddish color, and Vega has a blueish tint. In order by surface temperature, from coldest to hottest, these stars are ranked:
a) Proxima Cen, the Sun, Vega.
b) The Sun, Proxima Cen, Vega.
c) Proxima Cen, Vega, the Sun.
d) The Sun, Vega, Proxima Cen.
e) Vega, Proxima Cen, the Sun.

a) Proxima Cen, the Sun, Vega.

2. An excited atom is one in which:
a) an electron has gained energy and has jumped to a higher energy level.
b) an electron has jumped to a lower energy level, closer to the nucleus.
c) an electron has escaped from the atom.
d) an electron has collided with a positron and been annihilated, producing gamma rays.
e) an electron has been driven into the nucleus, merging with a proton to become a neutron.

a) an electron has gained energy and has jumped to a higher energy level.

3. If a moving object is not subject to any external forces, it will:
a) eventually slow down and stop moving.
b) move in a circular orbit at constant speed.
c) keep moving in a straight line at a constant speed.
d) keep moving in a straight line at a constant non-zero acceleration.
e) it depends upon the mass; a very massive object will stop moving, while a low mass object will keep going.

c) keep moving in a straight line at a constant speed.

4. In massive stars, after carbon is produced in the core, a series of nuclear reactions occur that build heavier and heavier elements. The main set of reactions that occur in these stars are called alpha capture reactions. What is an alpha capture reaction?
a) when a neutron fuses with an atomic nucleus.
b) when a proton fuses with an atomic nucleus.
c) when a deuterium nucleus fuses with an atomic nucleus.
d) when a helium nucleus fuses with an atomic nucleus.
e) when an electron fuses with an atomic nucleus.

d) when a helium nucleus fuses with an atomic nucleus.

5. The Sun has a mass 330,000 times that of the Earth. Therefore the gravitational force that the Sun exerts on the Earth is:
a) The same as the gravitational force the Earth exerts on the Sun.
b) 330,0000 times larger than the gravitational force the Earth exerts on the Sun.
c) 330,000 times smaller than the gravitational force the Earth exerts on the Sun.
d) 330,000² times the gravitational force the Earth exerts on the Sun.
e) 1/330,000² times the gravitational force the Earth exerts on the Sun.

a. The same as the gravitational force the Earth exerts on the Sun.

6. The observed spectrum of the Sun peaks:
a) in the UV.
b) in the optical.
c) in the IR.
d) at radio waves.
e) in the X-ray.

b. in the optical.

7. The plot to the right shows the velocity-vs.-time plot for a star perturbed by the motion of a planet. The shape of this curve tells astronomers that the extrasolar planet:
a) orbits the star in a perfect circle.
b) orbits the star in the plane of the sky.
c) orbits the star in an ellipse.
d) has hydrogen fusion in its core.
e) there is no evidence that extrasolar planets exist.

c) orbits the star in an ellipse.

8. To detect an extrasolar planet DIRECTLY (i.e., to see its disk or its spectrum), what wavelengths of light are best?
a) infrared.
b) visible.
c) ultraviolet.
d) radio waves.
e) X-rays.

a) infrared.

9. The core of our Sun will eventually become:
a) a neutron star.
b) a black hole.
c) a white dwarf.
d) it will eventually be completely destroyed in a supernova explosion.
e) an inert ball of iron.

c) a white dwarf.

10. Which of the following types of stars is the hottest?
a) F.
b) G.
c) K.
d) M.
e) O.

e) O.

11. The Local Group is the name of:
a) Our home galaxy.
b) The group of 3 stars that the Sun belongs to.
c) The group of galaxies our galaxy belongs to.
d) The group of planets that orbit our Sun.
e) A small irregular galaxy that orbits around the Milky Way.

c) The group of galaxies our galaxy belongs to.

12. How much longer will the Sun continue to fuse hydrogen to helium in its core?
a) about a thousand years.
b) about a million years.
c) about 5 billion years.
d) about 100 billion years.
e) we have no idea; it might stop tomorrow.

c) about 5 billion years.

13. The Milky Way and the Andromeda Galaxy:
a) are now both elliptical galaxies.
b) will eventually merge, producing an elliptical galaxy.
c) will eventually collide, annihilating all their matter, creating a huge burst of gamma rays.
d) are moving apart with time, and will never collide.
e) are both small irregular galaxies, much smaller than most of the other galaxies in the Local Group.

b) will eventually merge, producing an elliptical galaxy.

14. Which of the following types of main sequence stars uses up the hydrogen in its core most quickly, exploding as a supernova in approximately a million years?
a) F.
b) G.
c) K.
d) M.
e) O.

e) O.

15. In the core of a massive star (>8 solar masses), a sequence of nuclear fusion reactions will occur, until finally the core gravitationally collapses into a ball of neutrons, and then the star explodes as a supernova. What is the last chemical element produced by these reactions in the core before the star explodes?
a) carbon.
b) helium.
c) oxygen.
d) hydrogen.
e) iron.

e) iron.

16. The vapor lamps used in lab, containing hot low density gas, produce what kind of spectrum?
a) an emission-line spectrum.
b) an absorption-line spectrum.
c) a continuous spectrum, with all colors of the rainbow.
d) only infrared light.
e) only UV light.

a) an emission-line spectrum.

17. Once our Sun uses up all the hydrogen in its core, when the core gets sufficiently hot, the next set of nuclear reactions that will happen involve:
a) the production of iron from silicon.
b) the production of carbon from helium.
c) creating neutrons from protons plus electrons.
d) no more nuclear reactions will occur; the Sun's core will become a black hole.
e) the production of uranium from iron.

b) the production of carbon from helium.

18. The equation F = MA is known as:
a) The law of energy conservation.
b) The second law of thermodynamics.
c) The Drake Equation.
d) The electromagnetic relation.
e) Newton's Second Law.

e) Newton's Second Law.

19. A Doppler shift is:
a) a change in the velocity of an object, due to a force acting upon it.
b) a shift in the wavelength of the peak of the spectrum of an object, due to an increase in its temperature.
c) an increase in the mass of an atomic nucleus, due to fusion with another nucleus.
d) a change in the observed wavelength of light or sound, due to the relative motion of the source of the light/sound and the observer.
e) the slight dimming of a star, due to a planet moving in front of the star.

d) a change in the observed wavelength of light or sound, due to the relative motion of the source of the light/sound and the observer.

20. The Sun is approximately how old?
a) 10 million years.
b) 100 million years.
c) 4.6 billion years.
d) 460 billion years.
e) 4.6 trillion years.

c) 4.6 billion years.