Deck 10: The Sun As a Star

Question 1

What powers a star?

A) combustion
B) gravitational contraction
C) fusion
D) fission

Answer 1

fusion

Question 2

Approximately what fraction of the Solar System's mass is inside the Sun?

A) 50%
B) 75%
C) 90%
D) 99.9%

Answer 2

99.9%

Question 3

What is the fate of positrons produced through fusion in the Sun's core?

A) They escape without interacting with matter in the Sun.
B) They are annihilated.
C) They are carried to the surface through convection.
D) They are fused into larger nuclei.

Answer 3

They are annihilated.

Question 4

Arrange the following layers of the Sun in order from most to least dense.

A) radiative zone, core, photosphere, convective zone
B) core, convective zone, radiative zone, photosphere
C) core, radiative zone, convective zone, photosphere
D) radiative zone, convective zone, core, photosphere

Question 5

A fusion reaction between nuclei A and B releases energy if the resulting nucleus:

A) is less massive than the total mass of A and B.
B) has a lower temperature than the average of A and B.
C) is more massive than the total mass of A and B.
D) has a higher temperature than the average of A and B.

Question 6

Which of the following lists arranges its constituent nuclei in order from most tightly bound to least tightly bound?

A) helium, deuterium, oxygen, iron
B) deuterium, helium, iron, oxygen
C) iron, helium, deuterium, oxygen
D) iron, oxygen, helium, deuterium

Question 7

Which of the following properties decreases from the Sun's core to its outermost layer?

A) temperature
B) density
C) helium fraction
D) hydrogen line opacity

Question 8

The figure below shows the trajectories of particles produced within the Sun.Which kind of particle follows the trajectory labeled "X"?

A) gamma rays
B) positrons
C) neutrinos
D) neutrons

Question 9

The Sun produces energy through:

A) fission.
B) the triple alpha reaction.
C) the proton-proton chain.
D) the CNO cycle.

Question 10

How are oscillations of the Sun's surface measured?

A) the sunspot cycle
B) redshifts and blueshifts of absorption lines
C) variations in the solar luminosity
D) solar neutrinos

Question 11

The graph below shows the binding energy of atomic nuclei.Based on the energetics shown in this figure,which of the following is an allowable fusion reaction that would release energy?

A) helium-4 to Li-6
B) hydrogen-2 to carbon-12
C) Fe-56 to O-16
D) U-238 to Fe-56

Question 12

Where does fusion occur in the Sun?

A) the corona
B) the photosphere
C) the radiative zone
D) the core

Question 13

Which of the following mechanisms is a result of each and every star in the Universe?

A) nuclear fission
B) the formation of brown dwarfs
C) supernova explosions
D) chemical enrichment by heavy elements

Question 14

In which of the following ways are oxygen-16 and oxygen-17 the same?

A) number of protons
B) mass
C) number of neutrons
D) binding energy

Question 15

A star loses one billion kilograms of material per second as it fuses hydrogen to helium.Approximately how much energy does the star produce each second?

A) 9 × 10²⁵ joules
B) 3 × 10²⁵ joules
C) 4 × 10²⁶ joules
D) 3 × 10³¹ joules

Question 16

What is required to overcome the electrical repulsion of atomic nuclei?

A) high velocities
B) high densities
C) high binding energy
D) high luminosity

Question 17

What forces maintain hydrostatic equilibrium in an object?

A) centrifugal force and gravity
B) pressure and gravity
C) magnetism and gravity
D) radiation and pressure

Question 18

What has provided the best data about the interior of the Sun?

A) helioseismology
B) sunspots
C) the Sun's evolving luminosity
D) solar X-rays

Question 19

Which of the following is NOT identical among all isotopes of a given element?

A) number of protons
B) atomic number
C) atomic mass
D) proton number

Question 20

In which of the following ways are earthquakes and oscillations on the Sun similar?

A) They propagate through the entirety of the objects.
B) They are measured through the Doppler effect.
C) They are caused by energy released in the deep interior of the objects.
D) They are the primary method of energy transport from the deep interior of the objects.

Question 21

Sunspots always occur in:

A) 13-year cycles.
B) weak magnetic fields.
C) pairs.
D) the Sun's polar regions.

Question 22

Sunspots are areas of:

A) strong convection.
B) weak convection.
C) intense magnetic fields.
D) weak magnetic fields.

Question 23

The net result of the proton-proton chain in the Sun is to convert:

A) four protons to one helium-4 nucleus, one neutrino, one positron, and gamma rays.
B) four protons to one helium-4 nucleus, two neutrinos, two positrons, and gamma rays.
C) two protons to one helium-4 nucleus, one neutrino, one positron, and gamma rays.
D) six protons to one helium-4 nucleus, two neutrinos, two neutrons, and gamma rays.

Question 24

Which of the following is necessary for the solar dynamo to operate?

A) differential rotation
B) ionized gas
C) rapid rotation
D) all of the above

Question 25

Which of the following energy transport mechanisms does NOT occur to a significant degree in the Sun?

A) radiative transport
B) convection
C) conduction
D) thermal

Question 26

A convection cell on the Sun's surface fades away after approximately:

A) 20 minutes.
B) 28 days.
C) 11 years.
D) 10⁴ years.

Question 27

Why are sunspots dark?

A) They are moving downward toward the center of the Sun.
B) They have more dust than their surroundings.
C) They are less dense than their surroundings.
D) They are cooler than their surroundings.

Question 28

Why does fusion take place at very high temperatures?

A) Gamma rays, a product of fusion reactions, can only exist at very high temperatures.
B) High temperatures and pressures are required to confine the hydrogen plasma so that fusion can take place.
C) High temperatures mean high collisional velocities, which can allow protons to overcome their mutual electrical repulsion.
D) High temperatures produce bluer, more energetic photons that are required to initiate the fusion reaction sequence.

Question 29

When energy is carried by photons,astronomers call it:

A) conduction.
B) convection.
C) radiative energy transport.
D) coherence.

Question 30

Convection in the Sun can be observed through:

A) sunspots.
B) granulation.
C) solar flares.
D) solar neutrinos.

Question 31

Which of the following is true of the solar surface features seen in the image below?

A) The patterns are created in the chromosphere.
B) The dark spots have a higher temperature than the light spots.
C) The patterns are created by magnetic field variations.
D) The light spots have blueshifted absorption features.

Question 32

A large nucleus A has a smaller binding energy than a less massive nucleus B.Which of the following reactions could happen?

A) B could undergo a fission reaction to produce A, releasing energy.
B) A could undergo a fusion reaction to produce B, releasing energy.
C) B could undergo a fusion reaction to produce A, releasing energy.
D) A could undergo a fission reaction to produce B, releasing energy.

Question 33

Solar neutrinos:

A) change their identities en route to Earth.
B) were not detected in the expected numbers until 2002.
C) are a powerful probe of the proton-proton chain.
D) all of the above.

Question 34

Convection in the Sun is triggered when:

A) hydrogen becomes more neutral.
B) fusion causes gas instabilities.
C) magnetic fields drag the gas.
D) the solar interior is opaque to gamma rays.

Question 35

The Sun produces 4 × 10²⁶ joules per second through fusion of hydrogen.How does its mass decrease each second through this process?

A) 4 × 10⁶ kg/second
B) 4 × 10⁷ kg/second
C) 4 × 10⁸ kg/second
D) 4 × 10⁹ kg/second

Question 36

Which of the following aspects of sunspots varies regularly with the solar magnetic cycle?

A) latitude
B) size
C) temperature
D) all of the above

Question 37

What happens to a gamma ray photon produced in the Sun's interior as it travels through the radiative zone?

A) It breaks apart heavy nuclei, producing more energy.
B) It is trapped within a blob of gas and carried upward slowly.
C) It streams to the edge of the zone without interacting.
D) It scatters every few centimeters and is transformed into many lower energy photons.

Question 38

Approximately how long ago was the solar energy we see today produced by fusion?

A) 8 minutes
B) 30 days
C) 100 years
D) 10⁵ years

Question 39

The most direct measurement of the fusion reactions within the Sun comes from:

A) neutrinos.
B) its spectrum.
C) its luminosity.
D) helioseismology.

Question 40

A pot of boiling water sits on a hot stove.How is heat transported from the bottom of the pot to the water's surface?

A) radiative transport
B) convection
C) conduction
D) phase transitions

Question 41

What type of solar activity is shown in the image below?

A) solar flare
B) solar prominence
C) coronal mass ejection
D) coronal hole

Question 42

Which of the following is NOT related to the solar magnetic cycle?

A) the number of sunspots
B) space weather
C) the solar neutrino problem
D) the strength of Earth's aurorae

Question 43

How would the Sun change if it rotated as a solid body,like the planets do,rather than differentially?

A) It would have more sunspots.
B) It would have fewer field reversals.
C) It would have more flares.
D) It would be tidally locked.

Question 44

If scientists observe a coronal mass ejection,the Sun likely has:

A) fewer sunspots than usual.
B) just experienced a polarity reversal.
C) no magnetic field lines.
D) experienced recent reconnection events.

Question 45

Why does fusion occur only at the center of the Sun?

Question 46

Which of the following events have caused extensive power outages on Earth?

A) coronal mass ejections
B) meteor strikes
C) gamma ray bursts
D) supernovae

Question 47

A sunspot has a temperature 80% as large as the rest of the Sun's surface.How much LESS light does it produce per unit area than the rest of the Sun?

A) 5% as much
B) 20% as much
C) 40% as much
D) 80% as much

Question 48

Which of the following is a result of the solar dynamo?

A) Flux tubes above the radiative zone become buoyant and rise.
B) the differential rotation of the sun.
C) solar granulation
D) none of the above

Question 49

Before 2002,why did astronomers detect only a fraction of the neutrinos they expected from the Sun?

Question 50

The figure below shows the layers of the Sun,each labeled by a letter (from A at the center to F as the outermost layer).Identify all six of these layers by name.

Question 51

Sunspots are dark because:

A) dust particles congregate around magnetic fields.
B) magnetic fields decrease the gas temperature.
C) light is deflected by magnetic fields.
D) magnetic fields trigger line emission from the Sun's plasma.

Question 52

How does the Sun's rotation differ from Earth's?

Question 53

Through fusion,a star converts four hydrogen nuclei (each with a mass of 1.6726 × 10⁻²⁷ kg)to one heluim-4 nucleus (with a mass of 6.6465 × 10⁻²⁷ kg).
How much energy,in joules,is released in each such reaction?

Question 54

Suppose a pair of identical atomic nuclei are manipulated so that the first is given an extra neutron and the second is given an extra proton.Contrast the original and resulting nuclei in terms of mass,chemical properties,and electric charge.

Question 55

The figure below shows the proton-proton fusion chain within the Sun.What do the large green dots,small green dots,and large blue dots represent? (Each small "n" represents a neutrino,while each small "g" represents gamma rays.)

Question 56

What can astronomers learn by measuring the regular oscillations of material on the Sun's surface?

Question 57

What are the two properties that define a star?

Question 58

Differentiate nuclear fusion and fission.

Question 59

If the Sun has only a few sunspots today,all appearing at the middle latitudes,what will the surface look like in 11 years?

A) It will have few sunspots, in the middle latitudes.
B) It will have many sunspots, near the equator.
C) It will have few sunspots, near the poles.
D) It will have many sunspots, near the poles.

Question 60

If the Sun's magnetic field lines all closed in upon themselves,we would NOT see:

A) solar prominences.
B) solar granules.
C) sunspots.
D) the solar wind.

Question 61

A lightbulb illuminates a metal plate,heating it.The metal plate heats an iron rod on top of it.What processes are responsible for transporting energy from the bulb to the rod?

Question 62

What is the origin of the solar feature shown in the image below?

Question 63

Name three aspects of sunspots that depend strongly on the solar magnetic cycle.

Question 64

An astronomer discovers a region on the Sun's surface,roughly the size of Earth,that produces 80% less light than the rest of the Sun's surface.What is the most likely cause of this feature?

Question 65

What is the heliosphere?

Question 66

How can heat be transported across a vacuum?

Question 67

A blob of gas just above the Sun's radiative zone absorbs energy.How does this energy reach the Sun's surface?

Question 68

The figure below shows the configuration of magnetic field lines in the Sun at the beginning of a solar magnetic cycle.How do these field lines change as the Sun rotates?

Question 69

What provides the energy for solar flares?

Question 70

A sunspot is 16 times fainter than the solar material immediately next to it.If the Sun's surface is normally 5,800 K,how hot is the sunspot?