Deck 14: Our Starthe Sun

Question 1

If the Sun was not currently in hydrostatic equilibrium, we would see

A) more sunspots at all times.
B) more energetic solar flares.
C) the Sun's radius increasing or decreasing.
D) vastly more or fewer neutrinos than we detect.
E) the Sun's luminosity increasing or decreasing.

Answer 1

the Sun's radius increasing or decreasing.

Question 2

What do astronomers mean when they say that the Sun makes energy by hydrogen burning?

A) The Sun is combusting hydrogen in a fire and releasing energy.
B) The Sun is fusing hydrogen into uranium and releasing energy.
C) The Sun is creating hydrogen at very high temperatures.
D) The Sun is fusing hydrogen into helium and releasing energy.
E) The Sun is accumulating hydrogen from the solar wind and releasing energy.

Answer 2

The Sun is fusing hydrogen into helium and releasing energy.

Question 3

The figure below illustrates the proton-proton chain.How many gamma rays are produced for each helium (⁴He) nucleus created?

A) None
B) 2
C) 4
D) 6
E) 12

Answer 3

6

Question 4

Why is hydrogen burning the main energy source for main-sequence stars?

A) Hydrogen is the most common element in stars.
B) Hydrogen nuclei have the smallest positive charge.
C) Hydrogen burning is the most efficient of all fusion or fission reactions.
D) Hydrogen can fuse at temperatures lower than other elements.
E) All these are valid reasons.

Question 5

Because the Sun is in hydrostatic equilibrium, the correct order of the inner layers by density, from most dense to least dense, is

A) core, convective zone, radiative zone.
B) convective zone, radiative zone, core.
C) radiative zone, convective zone, core.
D) radiative zone, core, convective zone.
E) core, radiative zone, convective zone.

Question 6

Density, temperature, and pressure increase as you move inward in the interior of the Sun.This means that the weight of the star pushing inward at a given radius ________ as you move toward the core.

A) increases
B) decreases
C) stays the same
D) increases, and then decreases
E) There is not enough information to answer.

Question 7

Which force is responsible for holding the protons and neutrons in the nucleus of an atom together?

A) gravity
B) strong nuclear force
C) electric force
D) magnetic force
E) electrons pushing them together

Question 8

If the core of the Sun were hotter than it is now, how would the Sun's energy production change?

A) It would produce less energy per second than it does now.
B) It would produce more energy per second than it does now.
C) Its energy production would vary more than it does now.
D) Its energy production would be more stable than it is now.
E) The Sun's energy production would not change.

Question 9

Where does hydrostatic equilibrium exist in the Sun?

A) only in the core, where energy production via fusion can balance gravity
B) in the outer layers of the atmosphere, where most of the visible light is produced
C) just outside the core, where heat from nuclear fusion is transported outward
D) throughout the Sun's interior.
E) only in the photosphere.

Question 10

What is the approximate temperature at the center of the Sun?

A) 10⁶ K
B) 1.5 * 10⁷ K
C) 2.5 * 10⁷ K
D) 10,000 K
E) 10⁹ K

Question 11

Suppose by some mysterious process the nuclear fusion rate in the core of the Sun were to increase.What would certainly happen to the appearance of the Sun?

A) It would shrink in size.
B) It would become more luminous.
C) It would greatly increase in size.
D) It would become less luminous.
E) It would not change.

Question 12

Each helium atom created through the proton-proton chain, illustrated in the figure below, is made up of two protons and two neutrons.How many neutrons and protons are required as inputs to the proton-proton chain?

A) 2 neutrons, 2 protons
B) 0 neutrons, 6 protons
C) 6 neutrons, 0 protons
D) 4 neutrons, 0 protons
E) 3 neutrons, 3 protons

Question 13

The majority of the Sun's energy comes from

A) gravitational contraction.
B) nuclear fission of uranium.
C) hydrogen fusion.
D) helium burning.
E) burning material as in a fire.

Question 14

Hydrostatic equilibrium is a balance between

A) heat and centrifugal force.
B) core temperature and surface temperature.
C) pressure and gravity.
D) radiation and heat.
E) centrifugal force and gravity.

Question 15

When two atomic nuclei come together to form a new species of atom, this is called

A) nuclear fission.
B) nuclear recombination.
C) nuclear splitting.
D) nuclear fusion.
E) ionization.

Question 16

In the proton-proton chain, pictured in the figure below, what happens to the emitted gamma rays?

A) They quickly pass through the Sun's outer layers and are emitted into space.
B) They recombine to form electrons.
C) They eventually turn into neutrinos.
D) They are absorbed by other atoms, heating the Sun's core.
E) They are reflected around inside the Sun forever.

Question 17

The net result of the proton-proton chain of nuclear reactions is that four protons are converted into

A) one helium nucleus as well as energy, electrons, and neutrinos.
B) one helium nucleus as well as deuterium, electrons, and energy.
C) one helium nucleus, as well as energy, positrons, and neutrinos.
D) two helium nuclei, as well as neutrinos and positrons.
E) pure energy.

Question 18

The net effect of the proton-proton chain is that four hydrogen nuclei are converted to one helium nucleus and ________ are released.

A) visible wavelength photons
B) gamma ray photons, positrons, and neutrinos
C) ultraviolet photons and neutrinos
D) X-ray photons, electrons, and neutrinos
E) infrared photons and positrons

Question 19

The balance of energy in the solar interior means that

A) the energy production rate in the core equals the rate of radiation escaping the Sun's surface.
B) the source of energy in the core is stable and will sustain the Sun for millions of years.
C) the outer layers of the Sun absorb and re-emit the radiation from the core at increasingly shorter wavelengths.
D) radiation pressure does not contribute to supporting the weight of the overlying solar layers.
E) the core of the Sun has pressure that is lower than that of the outer layers.

Question 20

The energy that fuels the Sun is generated

A) only on its surface.
B) only in its core.
C) only in the solar wind.
D) both in its core and on its surface.
E) in its core, on its surface, and in the solar wind.

Question 21

The layers of the Sun's atmosphere, from innermost to outermost, are

A) corona, chromosphere, photosphere.
B) chromosphere, corona, photosphere.
C) photosphere, chromosphere, corona.
D) corona, photosphere, chromosphere.
E) photosphere, corona, chromosphere

Question 22

The interior zones of the Sun are distinguished by

A) jumps in density between zones.
B) their temperature profiles.
C) pressure differences inside each zone.
D) their modes of energy production transport.
E) all of these.

Question 23

By studying how the surface of the Sun vibrates like a struck bell we can determine its

A) age.
B) interior density.
C) total mass.
D) size.
E) temperature.

Question 24

Boiling water is an example of energy transport through

A) radiation.
B) convection.
C) conduction.
D) convection and conduction.
E) radiation and conduction.

Question 25

If you hold onto one end of a metal spoon after placing the other end in a pot of boiling water, you will burn your hand.This is an example of energy being transported by

A) radiation.
B) convection.
C) conduction.
D) convection and radiation.
E) radiation and conduction.

Question 26

In the radiative zone inside the Sun, photons are transported from the core to the convective zone over a time of

A) many thousands of years.
B) many millions of years.
C) seconds.
D) a few hours.
E) months.

Question 27

If the Sun converts 5 * 10¹¹ kg of H to He per second and 10 percent of the Sun's total mass is available for nuclear burning, how long might we expect the Sun to live?

A) 10⁴ years
B) 10⁸ years
C) 10¹⁰ years
D) 10¹¹ years
E) 10¹⁴ years

Question 28

If the rate of nuclear fusion in the Sun's core were to change, how long would it take for the Sun's luminosity to change?

A) months
B) a few hours
C) seconds
D) about 100,000 years
E) more than a million years.

Question 29

We can determine how density changes with radius in the Sun using

A) radar observations.
B) neutrino detections.
C) high-energy (gamma ray) observations.
D) helioseismology.
E) infrared observations.

Question 30

If the Sun converts 5 * 10¹¹ kg of H to He per second and the mass of a single hydrogen nucleus is 1.7 * 10^-27 kg, how many net proton-proton reactions go on per second in the Sun? What is the luminosity produced if the mass difference between a single helium nucleus and four hydrogen nuclei is 4 *10^-29 kg? Note that 1 watt =1 m² kg/s³.

A) 7 *10³⁷ reactions per second; 3 *10²⁶ watts
B) 3 * 10³⁸ reactions per second; 10²⁷ watts
C) 3*10³⁸ reactions per second; 4 * 10²⁶ watts
D) 7 *10³⁷ reactions per second; 5 * 10²⁵ watts
E) 3 * 10³⁷ reactions per second; 6 * 10²⁴ watts

Question 31

Which of the following layers of the Sun makes up the majority of its interior?

A) the core
B) the radiative zone
C) the convective zone
D) the photosphere
E) the chromosphere

Question 32

Approximately how long does it take the photons released in nuclear reactions in the core of the Sun to exit the Sun?

A) 8 minutes
B) 16 hours
C) 1,000 years
D) 100,000 years
E) 4.6 billion years

Question 33

If neutrinos oscillated between five different types of neutrino with equal probability during their transit from the Sun to Earth, and we could only detect one type of neutrino, then how many neutrinos would we have detected compared with what was emitted by the Sun?

A) one-half as many
B) one-third as many
C) one-fourth as many
D) one-fifth as many
E) We would detect no neutrinos.

Question 34

The solar neutrino problem was solved by

A) adjusting the rate of hydrogen burning in solar models.
B) Fixing a flaw in neutrino detector design that had reduced detection efficiency.
C) postulating that neutrinos had mass and oscillated between three different types.
D) lowering the percentage of helium in models of solar composition.
E) correctly measuring the density of the Sun's interior.

Question 35

What makes neutrinos so different from other particles of matter?

A) They interact very weakly with other particles.
B) They interact very strongly with other particles.
C) They are the only particles that move quickly.
D) They move very slowly.
E) They can only be found in atomic nuclei.

Question 36

How does the fact that the surface of the Sun rings like a bell help us better understand the Sun?

A) It tells us how quickly the Sun is expanding with time.
B) It helps us understand the solar interior better.
C) It reveals how rapidly the Sun's magnetic field is changing.
D) It helps us determine the surface temperature of the Sun.
E) It shows the relative gravitational strength of the orbiting planets.

Question 37

The detection of solar neutrinos confirms that

A) the Sun's core is powered by proton-proton fusion.
B) energy transport by radiation occurs throughout much of the solar interior.
C) magnetic fields are responsible for surface activity on the Sun.
D) convection churns the base of the solar atmosphere.
E) sunspots are cooler than the rest of the photosphere.

Question 38

Some restaurants place food under infrared heat lamps so that it stays warm after it has been cooked.This is an example of energy being transported by

A) radiation.
B) convection.
C) conduction.
D) convection and conduction.
E) radiation and conduction.

Question 39

The solar neutrino problem was solved by postulating that

A) neutrinos have a very large mass.
B) neutrinos oscillate between three different types.
C) some neutrinos become photons during their journey.
D) some neutrinos interact more strongly with matter such that they are absorbed locally inside the Sun.
E) neutrinos have zero mass like photons.

Question 40

Which of these can travel directly from the center of the Sun to Earth in about 8 minutes?

A) photons
B) electrons
C) protons
D) neutrons
E) neutrinos

Question 41

Suppose coronal holes covered a larger fraction of the Sun's surface than they currently do. Which of the following consequences would result?

A) The solar wind would contain a higher density of particles.
B) The solar wind would become hotter.
C) The solar wind would move faster.
D) The composition of the solar wind would change.
E) Nothing would change.

Question 42

In a sunspot, the umbra is

A) hotter than the penumbra.
B) cooler than the penumbra.
C) the same temperature as the penumbra.
D) brighter than the penumbra.
E) made of a different material than the rest of the surface.

Question 43

Sunspots appear dark because they have ________ than those of the surrounding gases.

A) densities that are higher
B) densities that are lower
C) pressures that are higher
D) temperatures that are lower
E) temperatures that are higher

Question 44

In the figure below, one can see that the Sun's surface appears darker towards the edges or "limbs" of the disk of the Sun.Why does this happen?

A) the chromosphere casts shadows on the edges of the Sun from our perspective.
B) the corona casts shadows on the edges of the Sun from our perspective.
C) the Sun is a higher temperature at the edges of the disk.
D) the viewing angle and lower temperature of the Sun's outer layers results in a dimming effect.
E) sunspots look much bigger when viewed edge-on.

Question 45

The Sun's corona has a temperature of approximately 1 million degrees.At what wavelength and in what part of the electromagnetic spectrum does its radiation peak?

A) 550 nm, visible
B) 2 * 10^-5 m, infrared
C) 4* 10^-7 m, ultraviolet
D) 3 *10^-9 m, X-rays
E) 6 m, radio

Question 46

The hottest layer of the solar atmosphere is the

A) outer convection zone.
B) photosphere.
C) chromosphere.
D) corona.
E) solar wind.

Question 47

The figure shown below, taken at visible wavelengths, shows a section of the Sun with sunspots visible.Which of the labeled regions is the lowest temperature?

A) region A
B) region B
C) region C
D) They are all the same temperature.
E) We would also need an X-ray image to determine relative temperatures.

Question 48

Which of the following are created by solar magnetic activity?

A) sunspots
B) prominences
C) coronal mass ejections
D) solar flares
E) all of these

Question 49

What force shapes the Sun's corona?

A) gravity
B) strong nuclear force
C) the Sun's magnetic field
D) the solar wind
E) sunspots

Question 50

Which of the layers of the Sun is located the farthest from the center of the Sun?

A) chromosphere
B) photosphere
C) radiative zone
D) convective zone
E) corona

Question 51

The solar spectrum is an example of a(n) ________ spectrum.

A) emission
B) absorption
C) continuum
D) blackbody
E) X-ray

Question 52

We know the Sun's corona is very hot because

A) we observe it emitting radiation at visible wavelengths.
B) the chromosphere and the photosphere are that hot, too.
C) we observe absorption from highly ionized atoms of iron and calcium in its spectrum.
D) the gas emits most of its radiation at radio wavelengths.
E) all of the above

Question 53

The best wavelength to use to observe a solar prominence is

A) 550 nm, green visible light.
B) 656 nm, a red hydrogen emission line.
C) 16 mm, an ultraviolet emission line.
D) 21 cm, microwave emission.
E) 0.02 nm, X-ray emission.

Question 54

The darkest part of a sunspot is called the

A) penumbra.
B) umbra.
C) granule.
D) photosphere.
E) magnetic field.

Question 55

The figure below shows the Sun during a solar eclipse at visible wavelengths.Which part of the Sun is visible around the shadow of the Moon?

A) chromosphere
B) photosphere
C) radiative zone
D) convective zone
E) corona

Question 56

The magnetic field of the Sun is continuously produced and deformed by

A) its differential rotation.
B) the solar wind.
C) changes in the rate of nuclear fusion in the core.
D) a liquid-conducting layer in the interior.
E) This is a trick question.The solar magnetic field is primordial.

Question 57

The Sun's internal magnetic field becomes tangled over time because of

A) coronal holes.
B) coronal mass ejections.
C) differential rotation.
D) temperature changes in the Sun's core.
E) all of these phenomena contribute.

Question 58

The Sun's chromosphere appears red because

A) it is hotter than the photosphere.
B) as the Sun rotates, the chromosphere appears to move away from us radially.
C) it has a higher concentration of heavy metals.
D) it is made of mostly helium.
E) its spectrum is dominated by H $\alpha$ emission.

Question 59

The surface of the Sun appears sharp when we look at it in visible light because

A) the photosphere is cooler than the layers below it.
B) the photosphere is thin compared with the other layers in the Sun.
C) the photosphere is much less dense than the convection zone.
D) its high luminosity provides plenty of photons, resulting in extreme definition.
E) the Sun has a distinct surface.

Question 60

In the figure labeled below, which solar layer is the chromosphere?

A) A
B) B
C) C
D) D
E) E

Question 61

What changes in the Sun's interior conditions could be noticed from the Earth, and how?

Question 62

The Maunder Minimum was a 60-year period when

A) debris from a comet collision blanketed the Sun.
B) almost no sunspots occurred on the Sun.
C) the Voyager 2 spacecraft traversed the heliopause.
D) very few dust storms occurred on Mars.
E) very few volcanic eruptions occurred on Mars.

Question 63

Explain why it is impossible to find a stable main-sequence star that is much hotter than the Sun, but has the same mass, composition, radius, and luminosity as the Sun.

Question 64

If a coronal mass ejection occurs on the Sun that expels material at a speed of 800 km/s, how long will it take these charged particles to reach the Earth?

A) about 8 minutes
B) several hours
C) about 2 days
D) about 1 week
E) around 1 month

Question 65

Solar wind particles hit the surface of the Moon, but they don't make it to the surface of the Earth because the Earth

A) is larger than the Moon.
B) is warmer than the Moon.
C) is shielded by the Moon.
D) has a magnetic field while the Moon does not.
E) is farther from the Sun than the Moon is.

Question 66

The solar magnetic field

A) returns to the same polarity every 11 years.
B) switches polarity every 22 years.
C) switches polarity every 11 years.
D) never changes polarity.
E) switches polarity every year.

Question 67

If a sunspot appears one-quarter as bright as the surrounding photosphere, and the average temperature of the photosphere is 5800 K, what is the temperature of the gas in this sunspot?

A) 3625 K
B) 4100 K
C) 4500 K
D) 5200 K
E) 5500 K

Question 68

When is the Sun most luminous?

A) when there are a maximum number of sunspots
B) when there are an average number of sunspots
C) when there are a minimum number of sunspots
D) The Sun's luminosity does not change.
E) The Sun's luminosity changes, but it has no relation to the number of sunspots.

Question 69

The region of dominance of the solar wind over the interstellar medium is called the

A) sunspot.
B) corona.
C) Kuiper belt.
D) heliosphere.
E) solar shock.

Question 70

If you observe a maximum number of sunspots right now, how long would you have to wait to see the next solar maximum?

A) 24 hours
B) 6 months
C) 1 year
D) 11 years
E) 22 years

Question 71

Explain why hydrostatic equilibrium results in the center of the Sun having the highest pressure and temperature.

Question 72

Through hydrogen fusion, the Sun loses approximately 4 million metric tons of mass each second.
If it burns hydrogen at this rate for 10 billion years, what percentage of its original mass will it
lose in all? (Note: The mass of the Sun is 1.99*10³⁰ kg, and 1 metric ton=1,000 kg.)

Question 73

In addition to the laws of physics and chemistry, what information do we need to know about our
Sun to calculate its internal structure and radius?

Question 74

When solar activity is very high, the Earth's atmosphere will

A) expand.
B) contract.
C) remain approximately the same.
D) repel charged particles.
E) block out sunlight.

Question 75

In the proton-proton chain, the net reaction is that four protons are converted into one helium nucleus.What other by-products are released in this reaction, and why?

Question 76

Why is hydrogen fusion the main energy source for main-sequence stars? Give at least two reasons.

Question 77

Calculate the amount of energy released by converting four hydrogen atoms into one helium atom.The mass of a hydrogen atom is 1.67 * 10^-27 kg; the mass of a helium atom is
6.65 * 10^-27 kg.The speed of light is 3 * 10⁸ m/s.

Question 78

List three methods of energy transport in nature and explain how the energy is being transferred in each of those methods.Which two are means by which energy is transported inside the Sun?

Question 79

The figure below shows a diagram of the Sun with zones labeled A, B, and C.Explain how energy is being transferred in each of the three regions.

Question 80

The Sun's magnetic field reverses direction every

A) 24 hours.
B) 27 days.
C) 12 months.
D) 11 years.
E) 22 years.