Download Study Guide Chapter 7

Astronomy
Review
for
Chapter
7­9
Test
You may bring in a 5” x 7” formulas note card with any problems worked on it and a separate note card
(same size) with any other information you like that is relevant for the test. Textbook use is not allowed.
What to study*
• The Universe: “Secrets of the Sun” video notes
• RedShift labs: “Star Colors”, “Star Brightness”,
“H-R Diagram” – especially study the conclusions
and summary tables in each lab.
• Bad Astronomy article – “Star Light, Star White”
• Chapter 7-9 Notes worksheets
• Chapter 7-9 Powerpoint notes
*Solutions to these documents can be found at
rhsweb.org/assignments/Nash/Astronomy/
Some practice problems
1. The temperature of a gas is a measure of the
a. total amount of internal energy in the gas.
b. amount of heat that flows out of the gas.
c. total number of atoms in the gas.
d. density of the gas.
e. average motion of its atoms.
2. The wavelength of maximum intensity that is
emitted by a black body is
a. proportional to temperature.
b. inversely proportional to temperature.
c. proportional to temperature to the fourth power.
d. inversely proportional to temperature to the fourth
power.
e. Both a and c above.
3. Of the following, which color represents the
lowest surface temperature star?
a. Yellow.
c. Orange.
b. Blue.
d. Red.
e. White.
4. The amount of electromagnetic energy radiated
from every square meter of the surface of a
blackbody each second is
a. proportional to temperature to the second power.
b. inversely proportional to temperature.
c. proportional to temperature to the fourth power.
d. inversely proportional to temperature to the fourth
power.
e. Both a and c above.
5. The B - V color index of a star indicates its
a. density.
d. chemical composition.
b. total mass.
e. surface temperature.
c. radius.
6. What conditions produce a dark (absorption line)
spectrum?
a. A hot solid, liquid, or high-density gas.
b. A hot low-density gas.
c. Light from a continuous spectrum source passing
through a cooler low-density gas.
d. Both a and b above.
e. All of the above.
7. Of the following spectral types, which one
represents a star with the highest surface
temperature?
a. A
b. B
c. F
d. K
e. G
8. You research the star Sirius and find that its
spectral lines are blue shifted. What does this tell
you about Sirius?
a. Its surface temperature is higher than that of the
Sun.
b. It has a transverse velocity that is away from us.
c. It has a transverse velocity that is toward us.
d. It has a radial velocity that is away from us.
e. It has a radial velocity that is toward us.
9. Which layer of the Sun's atmosphere contains the
cooler low-density gas responsible for absorption
lines in the Sun's spectrum?
a. The photosphere.
d. The solar wind.
b. The chromosphere.
e. All of the above.
c. The corona.
10. Which of the following is true about granules
and supergranules?
a. They are both about the same size.
b. Granules and supergranules each fade in about 10
to 20 minutes.
c. They are both due to convection cells in layers
below.
d. Both a and c above.
e. Both b and c above.
11. What are the general trends in temperature and
density from the photosphere to the chromosphere to
the corona?
a. The temperature increases and density decreases.
b. The temperature increases and density increases.
c. The temperature decreases and density decreases.
d. The temperature decreases and density increases.
e. The temperature and density remain constant.
12. What heats the chromosphere and corona to high
temperatures?
a. Long-wavelength electromagnetic radiation
emitted by layers below.
b. Visible light emitted by layers below.
c. Short-wavelength electromagnetic radiation
emitted by layers below.
d. Sungrazing comets, giving up their energy of
motion as they vaporize in these two layers.
e. Fluctuating magnetic fields from below that
transport energy outward.
17. Why can smaller parallax angles be measured by
telescopes in Earth orbit?
a. Telescopes orbiting Earth are closer to the stars.
b. Earth's atmosphere does not limit a telescope's
resolving power.
c. Earth's atmosphere does not limit a telescope's
light gathering power.
d. Earth's atmosphere does not limit a telescope's
magnifying power.
e. They can be connected to Earth-based telescopes
to do interferometry.
13. What is the source of the Sun's changing
magnetic field?
a. The differential rotation of the Sun.
b. Convection beneath the photosphere.
c. The Sun's large iron core.
d. Both a and b above.
e. Both a and c above.
18. How can a cool star be more luminous than a hot
star?
a. It can be more luminous if it is larger.
b. It can be more luminous if it is more dense.
c. It can be more luminous if it is closer to Earth.
d. It can be more luminous if it is farther from Earth.
e. A cool star cannot be more luminous than a hot
star.
14. How does the Sun maintain its energy output?
a. Gravitational contraction.
b. Fusion of hydrogen nuclei.
c. The impact of small meteoroids.
d. Coal burning in pure oxygen.
e. Fission of Uranium 235.
15. What evidence do we have that sunspots are
magnetic?
a. The spectral lines of sunspots are split by the
Zeeman Effect.
b. Observations show that the north pole and south
pole sunspots attract one another and move closer
together over time.
c. Observations at far ultraviolet show material
arched above the Sun's surface from one sunspot to
another.
d. Both a and b above.
e. Both a and c above.
16. Why does nuclear fusion require high
temperatures?
a. Protons have positive charge, and like charges
repel one another.
b. Two protons must get close enough together to
overcome the Coulomb barrier.
c. Two protons must get close enough for the strong
force to bind them together.
d. Both a and b above.
e. All of the above.
19. A star has one-half the surface temperature of the
Sun, and is four times larger than the Sun in radius.
What is the star's luminosity?
a. 64 solar luminosities.
b. 16 solar luminosities.
c. 4 solar luminosities.
d. 2 solar luminosities.
e. 1 solar luminosity.
20. In addition to the H-R diagram, what other
information is needed to find the distance to a star
whose parallax angle is not measurable?
a. The star's spectral type.
b. The star's luminosity class.
c. The star's surface activity.
d. Both a and b above.
e. All of the above.
Answers:
1e
2b
3d
4c
5e
6c
7b
8e
9a
10 c
11 a
12 e
13 d
14 b
15 e
16 e
17 b
18 a
19 e
20 d