CHAPTER 8—THE SUN-OUR STAR

Multiple Choice

Identify the letter of the choice that best completes the statement or answers the question.

____1.Granulation is caused by

a. / sunspots.
b. / rising gas below the photosphere.
c. / shock waves in the corona.
d. / the solar wind flowing away from the corona.
e. / the heating in the chromosphere.

____2.In some regions of the corona, the magnetic field does not loop back to the sun, and the gas escapes unimpeded. These regions are called ______and are believed to be the source of the solar wind.

a. / prominences
b. / flares
c. / granules
d. / auroras
e. / coronal holes

____3.Most of the light we see coming from the sun originates in the

a. / chromosphere.
b. / photosphere.
c. / corona.
d. / sunspots.
e. / magnetic field.

____4.A filtergram is a photograph of the sun's surface made

a. / in a band of wavelengths in the infrared.
b. / in a band of wavelengths in the ultraviolet.
c. / using the Zeeman effect.
d. / with only those photons emitted in a specific spectral line.
e. / none of the above

____5.Modern astronomers suspect the corona is heated by

a. / shock waves rising from below the photosphere.
b. / the solar wind.
c. / the solar magnetic field.
d. / all of these
e. / none of these

____6.Sunspots are known to be magnetic phenomena because

a. / Doppler shifts in spectral lines are observed.
b. / the Zeeman effect is observed in sunspots.
c. / collisional broadening is observed in spectral lines.
d. / infrared observations indicate that the sunspots are cooler than their surroundings.
e. / observations during eclipses reveal a very extensive photosphere.

____7.The solar constant is a measure of

a. / the amount of solar energy reaching the earth.
b. / the length of the sunspot cycle.
c. / the period of rotation of the sun's equator.
d. / the average number of sunspots seen during the Maunder minimum.
e. / the sun's mass.

____8.The sunspot cycle affects

I. / the latitude at which sunspots are visible at a given time.
II. / the number of sunspots that are visible at a given time.
III. / the rotation rate of the sun's equator at a given time.
IV. / the magnetic polarity of the sunspots at a given time.
a. / I & II
b. / I & IV
c. / II & III
d. / I, II & III
e. / I, II, & IV

____9.The sun's magnetic field is evident in the looped shapes of

a. / solar flares.
b. / sunspots.
c. / the corona.
d. / granules.
e. / solar prominences.

____10.Sunspots are dark because

a. / regions of the photosphere are obscured by material in the chromosphere.
b. / shock waves move through the photosphere.
c. / the sun rotates differentially.
d. / the strong magnetic field inhibits the currents of hot gas rising from below.
e. / they radiate their energy into space faster than the rest of the photosphere.

____11.The photosphere is very thin because

a. / the temperature of the photosphere increases rapidly from its base to its outer edge.
b. / the gas bubbles that form the granulation pattern cannot travel very far.
c. / the magnetic field compresses the photosphere.
d. / the H- ion is a very good absorber of photons and causes the gas of the photosphere to be opaque.
e. / the sun rotates differentially.

____12.The diagram below shows a plot of the temperature of the sun as a function of distance above the bottom of the photosphere. At what distance above the bottom of the photosphere does the temperature of the sun change the most rapidly with distance?

a. / 1,000 km
b. / 2,300 km
c. / 2,500 km to 4,000 km
d. / 500 km
e. / a and c

____13.The centers of granules

a. / are hot material rising to the photosphere from below.
b. / are cool material falling from the photosphere to the regions below.
c. / are fainter and hotter than their surroundings.
d. / are brighter and cooler than their surroundings.
e. / show strong Zeeman effects.

____14.What evidence supports the contention that other sun-like stars also show a spot cycle much like our sun's sunspot cycle?

a. / the variation in the rotation rates of sun-like stars
b. / the variation in the nuclear reaction rates in sun-like stars
c. / the variation in the strength of the H and K emissions in the spectra of sun-like stars
d. / the variation in the parallax of sun-like stars
e. / the variation in the color of sun-like stars

____15.Spicules

a. / are found in the photosphere.
b. / are magnetic disturbances that push large loops of material off the solar surface.
c. / are responsible for twisting the solar magnetic field and causing the sunspot cycle.
d. / appear in the corona near the north and south poles of the sun during a total solar eclipse.
e. / are visible in filtergrams of the solar chromosphere.

____16.The most recent sunspot maximum occurred in 2001, when is the next sunspot maximum expected if the solar cycle continues?

a. / 1990
b. / 2006
c. / 2012
d. / 2023
e. / The last cycle started a Maunder minimum, and the next maximum can not be predicted.

____17.The variation in the strength of the calcium H and K emission from sun-like stars implies that these stars

a. / probably have very extended coronae.
b. / probably have a magnetic cycle similar to the sun's.
c. / do not rotate differentially.
d. / may have planets that orbit them.
e. / probably have supergranules and spicules

____18.A ______is believed to occur when energy, stored in a twist in the solar magnetic field above a sunspot, is suddenly released.

a. / solar flare
b. / supergranule
c. / spicule
d. / coronal hole
e. / none of the above

____19.Sunspots

a. / are hotter than their surroundings.
b. / are regions where material is rising from below the photosphere.
c. / show the Zeeman effect indicating the presence of strong magnetic fields.
d. / produce spicules.
e. / are generally found near the poles of the sun during sunspot maximum.

____20.The ______is (are) the hot gases that are the moving extension of the sun's corona.

a. / spicules
b. / prominences
c. / flares
d. / supergranules
e. / solar wind

____21.The corona of the sun can be observed

a. / during a lunar eclipse.
b. / with a coronagraph.
c. / using filtergrams.
d. / a and b above
e. / with none of the above

____22.______occurs because photons we receive from the edge of the solar disk are emitted further from the base of the photosphere than the photons we receive from the center of the solar disk.

a. / The Zeeman effect
b. / Sunspots
c. / Solar flares
d. / Solar prominences
e. / Limb darkening

____23.The United States consumes 2.51019 J of energy each year. A typical solar flare releases 5.01024 J of energy. How many years could we run the United States on the energy released by this solar flare if all of the released energy could be used?

a. / 510-6 years
b. / 200,000 years
c. / 1.251044 years
d. / about 12 years
e. / 500 years

____24.If a sunspot has a temperature of 4,500 K and the surrounding solar surface has a temperature of 5,800 K, how many times brighter is the surface compared to the sunspot?

a. / 0.28
b. / 0.36
c. / 2.8
d. / 3.6
e. / 36

____25.The intensity of a sunspot is found to be 3 times smaller than the intensity emitted by the solar surface. What is the approximate temperature of this sunspot if the temperature of the solar surface is 5,800 K?

a. / 4,400 K
b. / 470,000 K
c. / 1,900 K
d. / 7,600 K
e. / 1,400 K

True/False

Indicate whether the sentence or statement is true or false.

____26.Most of the visible light from the sun originates in the photosphere.

____27.Granulation is caused by rising currents of hot gas below the photosphere.

____28.The flash spectrum shows that temperature falls with increasing height in the chromosphere.

____29.A filtergram is used to study layers below the photosphere.

____30.The corona is heated by the solar magnetic field.

____31.The Zeeman effect shows that sunspots contain magnetic fields.

____32.Sunspots are hotter than the photosphere.

____33.An older theory suggested that the corona was heated by shock waves from the convection zone.

____34.Solar flares have no known effect on the Earth.

____35.Solar prominences have twisted and looped shapes because of the solar magnetic field.

CHAPTER 8

Answer Section

MULTIPLE CHOICE

1.ANS:B

2.ANS:E

3.ANS:B

4.ANS:D

5.ANS:C

6.ANS:B

7.ANS:A

8.ANS:E

9.ANS:E

10.ANS:D

11.ANS:D

12.ANS:B

13.ANS:A

14.ANS:C

15.ANS:E

16.ANS:C

17.ANS:B

18.ANS:A

19.ANS:C

20.ANS:E

21.ANS:B

22.ANS:E

23.ANS:B

Note to the Instructor: This question requires the use of mathematics and is similar to the problems at the end of the chapter.

24.ANS:C

Note to the Instructor: This question requires the use of mathematics and is similar to the problems at the end of the chapter.

25.ANS:A

Note to the Instructor: This question requires the use of mathematics and is similar to the problems at the end of the chapter.

TRUE/FALSE

26.ANS:T

27.ANS:T

28.ANS:F

29.ANS:F

30.ANS:T

31.ANS:T

32.ANS:F

33.ANS:T

34.ANS:F

35.ANS:T