question

Where does an object on an elliptical orbit experience the greatest acceleration?

answer

where spacetime has the most curvature

question

Imagine that the Sun could be turned into a black hole without changing its mass. How would Earth's orbit change?

answer

Earth's orbit would not change.

question

Imagine that the Sun gained mass without changing its radius. How would the structure of spacetime change at the distance of Earth's orbit?

answer

Spacetime would become more curved at Earth's orbit.

question

From the viewpoint of an observer in the orbiting rocket, what happens to time on the other rocket as it falls toward the event horizon of the black hole?

answer

Time runs increasingly slower as the rocket approaches the black hole.

question

As the falling rocket plunges toward the event horizon, an observer in the orbiting rocket would see that the falling rocket __________.

answer

slows down as it approaches the event horizon, and never actually crosses the event horizon

question

From Part B, you know that from afar we'll never see the in-falling rocket cross the event horizon, yet it will still eventually disappear from view. Why?

answer

Its light will become so redshifted that it will be undetectable.

question

If you were inside the rocket that falls toward the event horizon, you would notice your own clock to be running __________.

answer

at a constant, normal rate as you approach the event horizon

question

If you were inside the rocket that falls toward the event horizon, from your own viewpoint you would __________.

answer

accelerate as you fall and cross the event horizon completely unhindered

question

All millisecond pulsars are now, or once were, members of binary-star systems.

answer

True

question

The fact that gamma-ray bursts are so distant means that they must be very energetic events.

answer

True

question

All things, except light, are attracted by gravity.

answer

False

question

According to general relativity, space is warped, or curved, by matter.

answer

True

question

Although visible light cannot escape from a black hole, high-energy radiation, like gamma rays, can escape.

answer

False

question

A neutron star is about the same size as

answer

A U.S. city

question

Thousands of black holes have now been identified in our Galaxy.

answer

False

question

The most rapidly "blinking" pulsars are those that

answer

spin fastest

question

The X-ray emission from a neutron star in a binary system comes mainly from

answer

heated material in an accretion disk around the neutron star.

question

Gamma-ray bursts are observed to occur

answer

approximately uniformly over the entire sky.

question

If the Sun were magically to turn into a black hole of the same mass,

answer

Earth's orbit would remain unchanged.

question

The best place to search for black holes is in a region of space that

answer

has strong X-ray emission.

question

In a neutron star, the core is

answer

made of compressed neutrons in contact with each other.

question

Two important properties of young neutron stars are

answer

extremely rapid rotation and a strong magnetic field.

question

An object more massive than the Sun, but roughly the size of a city, is a

answer

neutron star

question

The mass range for neutron stars is

answer

1.4 to 3 solar masses

question

Neutron stars have

answer

very strong bi-polar magnetic fields.

question

In the Lighthouse Model,

answer

if the beam sweeps across us, we will detect a pulse of radiation.

question

Neutron stars do not have

answer

rotation periods comparable to the Sun's.

question

The supernova of 1054 AD produced:

answer

a pulsar with a period of 33 milliseconds, visible optically.

question

Three terrestrial-sized planets in orbits of a fraction of an AU have been found near

answer

a millisecond pulsar.

question

Almost half of all known millisecond pulsars are found in what type of object?

answer

globular clusters

question

X-ray bursters occur in binary star systems. The two types of stars that must be present to make up such an object are:

answer

a main sequence or giant star and a neutron star in a mass transfer binary.

question

Pulsars have a measured mass of

answer

about 1.4 solar masses.

question

You would expect millisecond pulsars to be

answer

part of a binary system.

question

A proposed explanation for gamma-ray bursters is A-coalescence of a neutron star binary. B-hypernova-making black holes and bi-polar jets. C-collisions between two white dwarfs. Both A and B are possible. All three are possible.

answer

Both A and B are possible.

question

What would happen if more mass was added to a 1.4 solar mass neutron star?

answer

It could eventually become a black hole, via a hypernova explosion.

question

A hypernova creates

answer

A black hole

question

The densely packed neutrons of a neutron star cannot balance the inward pull of gravity if the total mass is

answer

greater than Schwartzschild's limit of 3 solar masses.

question

The Schwartzschild radius for a 12 solar mass star is

answer

36 km

question

What explanation does general relativity provide for gravity?

answer

Gravity is the result of curved spacetime.

question

An observer on a planet sees a spaceship approaching at 0.5c. A beam of light projected by the ship would be measured by this observer to travel at

answer

c.

question

As a spaceship's velocity gets closer to the speed of light

answer

its length will decrease and its clock will run more slowly.

question

If light from a distant star passes close to a massive body, the light beam will

answer

bend towards the star due to gravity.

question

What can we detect from matter that has crossed an event horizon?

answer

Nothing

question

As a spaceship nears an event horizon, a clock on the spaceship will be observed

answer

to run slowly

question

If the Sun were replaced by a one solar mass black hole

answer

we would still orbit it in a period of one year.

question

What is Cygnus X-1?

answer

the leading candidate for an observable black hole binary system

question

A method for identifying a black hole is to

answer

look for their effects on nearby companions.

question

The largest known black holes

answer

lie in the cores of the most massive galaxies.

question

Any main sequence star over 25 solar masses will probably retain enough matter in its core after its type II supernova to make a black hole.

answer

True

question

The Schwarzschild radius of a black hole is about 3 km per solar mass; it is amazingly linear over a wide range of masses.

answer

True

question

Special relativity says that c, the speed of light, is the maximum velocity for both matter and energy in our universe.

answer

True

question

Who discovered the first four pulsars?

answer

Jocelyn Bell

question

In a neutron star, the protons and electrons are fused together, leaving only neutrons.

answer

True

question

A neutron star is what remains after a Type II supernova explosion has destroyed the rest of the star.

answer

True

question

In a neutron star, the electrons in the core are all in contact with each other.

answer

False

question

The "pulse" from a pulsar is due to the rapidly expanding and contracting outer shell of the star.

answer

False

question

Pulsars are created in a Type I supernova.

answer

False

question

The pulses from a pulsar are most likely coming from localized areas near the magnetic poles.

answer

True

question

While most pulsars slow down over time, millisecond pulsars spin faster due to the mass transfer from a close companion.

answer

True

question

An X-ray burster is similar to a nova.

answer

True

question

Gamma-ray bursts are all found to be within our galaxy.

answer

False

question

Gamma-ray bursters seem scattered randomly over the entire sky.

answer

True

question

All the gamma-ray bursters measured to date have distances of millions or even billions of light years.

answer

True

question

All Type II supernovae produce neutrons stars when they collapse.

answer

False

question

Both space and time are warped near the strong gravitational fields of neutron stars and black holes.

answer

True

question

No communication is possible across an event horizon.

answer

True

question

The presently known laws of physics clearly describe the conditions inside a black hole's event horizon.

answer

False

question

The radius of a white dwarf is determined by a balance between the inward force of gravity and the outward push of _________

answer

electron degeneracy pressure

question

A(n) __________ occurs when hydrogen fusion ignites on the surface of a white dwarf in a binary system.

answer

nova

question

A(n) _________ occurs when fusion creates iron in the core of a star.

answer

massive star supernova

question

A white dwarf in a close binary system will explode as a supernova if it gains enough mass to exceed the ________.

answer

white dwarf limit (1.4 solar masses)

question

A(n) _______ consists of hot, swirling gas captured by a white dwarf (or neutron star or black hole) from a binary companion star.

answer

accretion disk

question

A(n) ________ can occur only in a binary system, and all such events are thought to have the same luminosity.

answer

white dwarf supernova

question

All of the single red-dwarf stars that ever formed are still on the main sequence today.

answer

True

question

The Sun will get brighter as it begins to run out of fuel in its core.

answer

True

question

A planetary nebula is the disk of matter around a star that will eventually form a planetary system.

answer

False

question

The various stages of stellar evolution predicted by theory can best be tested by observations of stars in clusters.

answer

True

question

A nova is a sudden outburst of light coming from an old main-sequence star.

answer

False

question

It takes less and less time to fuse heavier and heavier elements inside a high-mass star.

answer

True

question

In a core-collapse supernova, the outer part of the core rebounds from the inner, high-density core, destroying the entire outer part of the star.

answer

True

question

Because of stellar nucleosynthesis, the spectra of old stars show more heavy elements than those of young stars.

answer

False

question

A white dwarf is supported by the pressure of tightly packed

answer

electrons

question

A star like the Sun will end up as a

answer

White Dwarf

question

A white dwarf can dramatically increase in brightness only if it

answer

Has another star nearby

question

Nuclear fusion in the Sun will

answer

create elements up to and including oxygen.

question

Most of the carbon in our bodies originated in

answer

the core of a red-giant star.

question

If the evolutionary track in Overlay 3, showing a Sun-like star, were instead illustrating a significantly more massive star, its starting point (stage 7) would be

answer

up and to the left

question

A star (no matter what its mass) spends most of its life:

answer

As a main sequence star

question

When a star's inward gravity and outward pressure are balanced, the star is said to be

answer

in hydrostatic equilibrium.

question

What temperature is needed to fuse helium into carbon?

answer

100 million K

question

A star is on the horizontal branch of the H-R diagram. Which statement is true?

answer

It is burning both hydrogen and helium.

question

During the hydrogen shell burning phase

answer

the star grows more luminous.

question

A solar mass star will evolve off the main sequence when

answer

it builds up a core of inert helium.

question

A surface explosion on a white dwarf, caused by falling matter from the atmosphere of its binary companion, creates what kind of object?

answer

Nova

question

Virtually all the carbon-rich dust in the plane of the galaxy originated in

answer

Low mass stars

question

An iron core cannot support a star because

answer

iron cannot fuse with other nuclei to produce energy.

question

A 20 solar mass star will stay on the main sequence for 10 million years, yet its iron core can exist for only a

answer

day

question

As a star's evolution approaches the Type II supernova, we find A.) helium to carbon fusion takes at least 100 million K to start. B.) the heavier the element, the higher the temperature to fuse it. C.) photo disintegration of iron nuclei begins at 10 billion K to ignite the supernova. D.) the heavier the element, the less time it takes to make it. E.) All of the above

answer

All of the above

question

As a 4-10 solar mass star leaves the main sequence on its way to becoming a red supergiant, its luminosity

answer

remains roughly constant.

question

Which of the following best describes the evolutionary track of the most massive stars?

answer

Horizontal right

question

If it gains sufficient mass, a white dwarf can become a

answer

type I supernova.

question

For a white dwarf to explode entirely as a Type I supernova, it's mass must be

answer

1.4 solar masses, the Chandrasekhar Limit

question

The heaviest nuclei of all are formed

answer

in the core collapse that set the stage of Type II supernovae.

question

The Chandrasekhar limit is

answer

the upper mass limit for a white dwarf.

question

Where was supernova 1987a located?

answer

in our companion galaxy, the Large Magellanic Cloud

question

Which of these events is not possible?

answer

white dwarfs and companion stars producing recurrent Type I supernova events

question

Which of these does not depend on a close binary system to occur?

answer

a Type II supernova

question

What can you conclude about a Type I supernova?

answer

It was originally a low-mass star.

question

A recurrent nova could eventually build up to a

answer

Type I supernova

question

The brightest stars of a young open cluster will be

answer

massive blue main sequence stars.

question

Noting the turnoff mass in a star cluster allows you to determine its

answer

age

question

Compared to a cluster containing type O and B stars, a cluster with only type F and cooler stars will be

answer

older

question

Which stars in globular clusters are believed to be examples of mergers?

answer

blue stragglers

question

What made supernova 1987a so useful to study? A. We saw direct evidence of nickel to iron decay in its light curve. B. Its progenitor had been observed previously. C. In the Large Magellanic Cloud, we already knew its distance. D. It occurred after new telescopes, such as Hubble, could observe it very closely. E. All of these are correct.

answer

All of these are correct.

question

While more massive than most of its neighbors, the Sun is still technically a low mass star.

answer

true

question

A massive star can fuse only up to the element silicon in its core.

answer

False

question

Because they all involve formation of iron in cores of massive stars, all type II supernovae are equally luminous.

answer

False

question

Because they all involve the detonation of a carbon-rich white dwarf at Chandrasekhar's limit, all type I supernovae are equally luminous.

answer

True

question

Novae are more closely related to type II than to type I supernovae.

answer

False

question

A carbon-detonation supernova starts out as a white dwarf in a close binary system.

answer

True

question

Most of the energy released during a supernova is emitted as neutrinos.

answer

True

question

Which of these is true of planetary nebulae?

answer

They are ejected envelopes surrounding a highly evolved low-mass star.

question

Compared to our Sun, a typical white dwarf has

answer

about the same mass and a million times higher density.

question

Which of these evolutionary paths is the fate of our Sun?

answer

Planetary Nebula

question

Black dwarfs are

answer

not found yet; the oldest, coldest white dwarf in the Galaxy has not cooled enough yet.

question

About 90% of the star's total life is spent on the main sequence.

answer

True

question

Paradoxically, while the core of the red giant is contracting and heating up, its radiation pressure causes its photosphere to swell up and cool off.

answer

True

question

A star may undergo two or more red giant expansion stages.

answer

True

question

A star system may undergo two or more nova outbursts.

answer

True

question

Our Sun will eventually become a nova.

answer

False

question

Today the majority of the mass of the universe is already in the form of black dwarfs, the solution to the "dark matter" problem.

answer

False

question

White dwarfs were once the cores of stars that produced planetary nebulae.

answer

True

question

It is the formation of iron in an evolved giant's core that triggers the Type II supernova event.

answer

True

question

In the cores of the most massive stars, the electrons and protons fuse together and form neutrons.

answer

False

question

Elements heavier than iron are formed mainly in supernovae.

answer

True

question

Supergiants are burning different fuels in several shells around the core.

answer

True

question

A star system can become a Type I supernova several times.

answer

False

question

Neutrinos can move faster than c, the speed of light, as was discovered in SN1987A in 1987.

answer

False

question

The spectra of the oldest stars show the most heavy elements.

answer

False

question

As a clump of interstellar gas contracts to become a main-sequence star, its changing position on the H-R diagram tells us __________.

answer

how its outward appearance is changing

question

Watch the red dot representing the protostar in the animation. After it reaches its highest point on the diagram, how do the protostar's surface temperature and luminosity change as it approaches the main sequence?

answer

Its surface temperature increases, but its luminosity decreases.

question

When does a newly forming star have the greatest luminosity?

answer

when it is a shrinking protostar with no internal fusion

question

When a newly forming star is at its greatest luminosity, what is its energy source?

answer

gravitational contraction

question

How do the properties of long-lived stars compare to those of short-lived stars?

answer

Long-lived stars begin their lives with less mass and a smaller amount of hydrogen fuel. Long-lived stars are less luminous during their main-sequence lives.

question

A main-sequence star twice as massive as the Sun would last __________.

answer

much less than half as long as the Sun

question

If stars A and B are both main-sequence stars and star A has a greater fusion rate than star B, which of the following statements hold(s)?

answer

Star A must be more luminous than star B. Star A must be more massive than star B.

question

The formation of the first high-mass stars in a collapsing cloud tends to inhibit further star formation within that cloud.

answer

True

question

A protostar that will eventually turn into a star like the Sun is significantly

answer

More luminous

question

Interstellar matter is quite evenly distributed throughout the Milky Way Galaxy.

answer

False

question

Twenty-one-centimeter radiation observations can be used to probe the interiors of molecular clouds.

answer

False

question

More massive stars form more rapidly.

answer

True

question

Brown dwarfs take a long time to form, but will eventually become visible as stars on the lower main sequence.

answer

False

question

Most stars form as members of groups or clusters.

answer

True

question

A dark interstellar globule is about the same size as

answer

The Oort Cloud

question

Of the following telescopes, the one best suited to observing dark dust clouds is

answer

A radio telescope

question

Interstellar gas is composed of

answer

90% hydrogen, 9% helium by weight.

question

What effect does even thin clouds of dust have on light passing through them?

answer

It dims and reddens the light of all more distant stars.

question

Which statement about the dark nebulae is true?

answer

They can be penetrated only with longer wavelengths such as radio and infrared.

question

Some regions along the plane of the Milky Way appear dark because

answer

stars in that region are hidden by dark dust particles.

question

Due to absorption of shorter wavelengths by interstellar dust clouds, distant stars appear

answer

redder

question

Which statement is true about the interstellar medium?

answer

We know more about the gas than the dust.

question

The spectra of interstellar gas clouds show that they have the same basic composition as

answer

Stars

question

Emission nebulae like M42 occur only near stars that emit large amounts of

answer

Ultraviolet Radiation

question

What is the primary visible color of an emission nebula?

answer

red due to ionized hydrogen atoms

question

The density of interstellar dust is very low, yet it still blocks starlight because

answer

the dust particles are about the same size as the light waves they absorb.

question

The gas density in an emission nebula is typically about how many particles per cc?

answer

Hundred

question

What two things are needed to create an emission nebulae?

answer

hot stars and interstellar gas, particularly hydrogen

question

A large gas cloud in the interstellar medium that contains several type O and B stars would appear to us as

answer

an emission nebula.

question

Which of these is not a consequence of dust in the interstellar medium?

answer

red light from the emission nebulae

question

Why are dark dust clouds largely misnamed?

answer

They contain much more gas than dust.

question

Complex molecules in the interstellar medium are found

answer

primarily in the dense dust clouds.

question

Interstellar dust clouds are best observed at what wavelength?

answer

Radio and infrared

question

When an electron in H changes its spin from the same to the opposite direction as the proton, it

answer

emits a radio wave photon.

question

A newly formed protostar will radiate primarily at which wavelength?

answer

infrared

question

During a protostar's T Tauri phase, it

answer

may develop very strong winds.

question

Which statement about the stages of starbirth is false?

answer

nuclear reactions begin in the core by stage 4.

question

On an H-R diagram, a protostar would be

answer

above and to the right of the main sequence.

question

A cloud fragment too small to collapse into a main sequence star becomes a

answer

Brown dwarf

question

How long does it take an M class star to reach the main sequence, compared to a solar type star?

answer

about twenty times longer

question

All globular clusters in our Milky Way are about how old?

answer

Around ten billion years old

question

What are the characteristics of an open cluster of stars?

answer

a few hundred, mainly main sequence stars

question

Which is characteristic of globular star clusters?

answer

old age and hundreds of thousands of stars, only about 30 ly wide

question

Most stars in our part of the Galaxy are formed

answer

in open clusters of a few dozen.

question

There is as much mass in the voids between the stars as in the stars themselves.

answer

True

question

Interstellar matter is distributed very evenly through the galaxy.

answer

False

question

The gas in the interstellar medium consists of mostly heavy elements.

answer

False

question

Molecular clouds are much warmer than typical interstellar gas clouds.

answer

False

question

Dark nebulae are opaque to all wavelengths of electromagnetic radiation.

answer

False

question

The 21 cm line of hydrogen is strongly absorbed by interstellar dust.

answer

False

question

What information does 21-cm radiation provide about the gas clouds?

answer

their motion; their distribution; their density; their temperature

question

Light from distant stars that must pass through dust arrives bluer than when it left its star.

answer

False

question

The predominant color of emission nebula is blue.

answer

False

question

Emission nebulae get their red color from the red supergiants forming in them.

answer

False

question

Dark dust clouds are optically invisible, but give off radio energy.

answer

True

question

Dark dust clouds are cooler than their surroundings.

answer

True

question

Globular clusters are typically much older than open clusters.

answer

True

question

Globular clusters contain mostly blue stars.

answer

False

question

Compared to a main-sequence star with a short lifetime, a main-sequence star with a long lifetime is __________.

answer

less luminous, cooler, smaller, and less massive

question

Compared to a high-luminosity main-sequence star, stars in the upper right of the H-R diagram are

answer

Cooler and larger in radius

question

Compared to a low-luminosity main-sequence star, stars in the lower left of the H-R diagram are

answer

Hotter and smaller in radius

question

Red giants are very bright because they are extremely hot.

answer

False

question

Star A appears brighter than star B, as seen from Earth. Therefore, star A must be closer to Earth than star B.

answer

False

question

The radius of a star can be indirectly determined if the star's distance and luminosity are known.

answer

False

question

Astronomers can distinguish between main-sequence and giant stars purely by spectroscopic means.

answer

True

question

In a spectroscopic binary, the orbital motion of the component stars appears as variations in the overall apparent brightness of the system.

answer

False

question

From a distance of 1 parsec, the angular size of Earth's orbit would be

answer

2 arc seconds

question

Compared with a star of absolute magnitude -2 at a distance of 100 pc, a star of absolute magnitude 5 at a distance of 10 pc will appear

answer

Fainter

question

Stars of spectral class M do not show strong lines of hydrogen in their spectra because

answer

their surfaces are so cool that most hydrogen is in the ground state.

question

Cool stars can be very luminous if they are very

answer

Large

question

The mass of a star may be determined

answer

by studying its orbit around a binary companion.

question

If a star has a parallax of 0.05", then its distance in light years is about:

answer

65 light years

question

Which statement about stellar motion is incorrect?

answer

Like parallax, proper motion is measured over intervals of exactly six months.

question

What physical property of a star does the spectral type measure?

answer

Temperature

question

The star's color index is a quick way of determining its:

answer

Temperature

question

On the H-R diagram, the Sun lies

answer

about the middle of the main sequence.

question

On the H-R diagram, white dwarfs lie Sirius B and Procyon B lie

answer

at lower left

question

On the H-R diagram, red supergiants like Betelguese lie

answer

at top right

question

Which type of binary can have their sizes measured directly by photometry?

answer

eclipsing

question

In what range of masses are most stars found?

answer

0.1 to 2 solar masses

question

The nearest star to our Sun, Alpha Centauri, is still over a parsec distant.

answer

True

question

A type B9 star is hotter than a type A0.

answer

True

question

The vast majority of stars near us would fall to the bottom right on the H-R diagram.

answer

True

question

A star's absolute magnitude is its apparent brightness as seen from

answer

33 light years distant

question

What can be said with certainty about a red star and a blue star?

answer

The blue star is hotter than the red star

question

The H-R diagram can plot

answer

temperature vs luminosity

question

On the H-R diagram, the bright blue stars that dominate the naked-eye sky lie

answer

at the top left.

question

A star near the lower right of the H-R diagram is likely to be

answer

red with low luminosity

question

Binary stars separated enough to be resolved in a telescope are called

answer

visual binaries

question

A parsec is about 3.3 light years.

answer

True

question

Less than 100 stars lie within 5 parsecs of the Sun.

answer

True

question

Our nearest stellar neighbor is a little less than 1 parsec away.

answer

False

question

A type B star is bluer than a type G star.

answer

True

question

Only A type stars show hydrogen lines in their spectra.

answer

False

question

White dwarfs lies on the lower left portion of the H-R diagram.

answer

True

question

Our Sun lies about the middle of the main sequence and the H-R diagram.

answer

True

question

Main sequence stars are fusing hydrogen into helium in their cores.

answer

True

question

The mass of a newly formed star will determine its position on the main sequence.

answer

True

question

Most stars are single stars like our own.

answer

False

question

In describing other stellar properties, almost everything is relative to our Sun.

answer

True

question

In which of the following layers of the Sun does nuclear fusion occur?

answer

Core

question

Which of the following layers of the Sun can be seen with some type of telescope? Consider all forms of light, but do not consider neutrinos or other particles.

answer

Corona, Photosphere, Chromosphere

question

Nuclear fusion of hydrogen into helium occurs in the ____

answer

Core

question

Energy moves through the sun's ______________ by means of the rising of hot gas and falling of cooler gas.

answer

Convection Zone

question

Nearly all the visible light we see from the Sun is emitted from the ___________.

answer

Photosphere

question

Most of the Sun's ultraviolet light is emitted from the narrow layer called the ____________ where temperature increases with altitude.

answer

Chromosphere

question

We can see the Sun's _________ most easily during total solar eclipses

answer

Corona

question

The ______________ is the layer of the Sun between its core and convection zone

answer

Radiation Zone

question

The most abundant element in the Sun is hydrogen.

answer

True

question

The density and temperature in the solar corona are much higher than in the photosphere.

answer

False

question

Sunspots appear dark because they are hotter than the surrounding gas of the photosphere.

answer

False

question

Flares are caused by magnetic disturbances in the lower atmosphere of the Sun.

answer

True

question

The proton-proton chain releases energy because mass is created in the process.

answer

False

question

Neutrinos have never been detected experimentally.

answer

False

question

Compared with Earth's diameter, the Sun's diameter is about

answer

100 times larger

question

The Sun spins on its axis roughly once each

answer

month

question

If astronomers lived on Venus instead of on Earth, the solar constant they measure would be

answer

Larger

question

A typical solar granule is about the size of

answer

Large U.S. State

question

The time between successive sunspot maxima is about

answer

Decade

question

The primary source of the Sun's energy is

answer

fusion of light nuclei to make heavier ones

question

From inside out, which is in the correct order for the structure of the Sun?

answer

radiative zone, convective zone, chromosphere

question

How long does the sunspot cycle last, on average?

answer

11 years

question

Visible sunspots lie in the

answer

granulation in the photosphere.

question

As the Sun rotates, an individual sunspot can be tracked across its face. From eastern to western limb, this takes about

answer

2 weeks

question

The most striking example of solar variability was the

answer

Maunder Minimum from 1645-1715.

question

Sunspots

answer

come in pairs, representing the north and south magnetic fields.

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During a period of high solar activity, the corona

answer

Is more irregular

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Sunspots are dark splotches on the Sun. Which statement is true?

answer

They are extremely hot, but cooler than the surrounding areas of the Sun.

question

Suppose a large flare is detected optically. How long until radio interference arrives?

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Simultaneously

question

While observing the Sun, you note a large number of sunspots. What can you conclude?

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There are likely to be an above average number of flares and prominences.

question

What natural barrier tries to prevent two protons from combining?

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electromagnetic repulsion

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The critical temperature to initiate the proton-proton cycle in the cores of stars is:

answer

10 Million K

question

In the proton-proton cycle, the helium atom and neutrino have less mass than the original hydrogen. What happens to the "lost" mass?

answer

It's converted to energy

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The primary source of the Sun's energy is

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the strong force fusing hydrogen into helium.

question

In the proton-proton cycle, the positron is

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An anti-electron

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Which is the net result of the proton-proton chain?

answer

4 protons = 1 helium 4 + 2 neutrinos + gamma rays

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The photosphere is about 100 times the diameter of the Earth, and large sunspots are larger than our whole planet.

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True

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Granulation is the most obvious proof of solar convective energy transport.

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True

question

The solar corona is much cooler than the Sun's surface, hence we must wait for a total solar eclipse to glimpse it with the naked eye.

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False

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What is the meaning of the solar constant?

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the amount of energy the Earth receives per unit area and unit time

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The density of the Sun is most similar to which object?

answer

Jupiter

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Which of these are not associated with the active Sun? aurora flares sunspots prominences granulation

answer

Granulation

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The outward pressure of hot gas in the Sun

answer

is balanced by the inward gravitational pressure.

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The Sun's radius is one astronomical unit by definition.

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False

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The Sun's structure is uniform throughout its interior, with no evidence of different layers.

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False

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The Sun's magnetic field is very weak compared to Earth's.

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False

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Sunspots usually come in pairs, each a magnetic pole.

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True

question

The sunspot cycle averages about 11 months.

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False

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Although sunspots are cooler areas in the photosphere, an increase in their number tells us the Sun is becoming more active.

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True

question

The solar corona is best studied using X-ray telescopes.

answer

True

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The solar neutrinos observed on Earth come from the hot spots in the corona.

answer

False

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The Sun produces energy by fusing hydrogen into helium.

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True

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During the fusion process, mass is converted into energy.

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True

question

The Solar Neutrino Problem is that we observe more neutrinos than predicted.

answer

False

Mastering Astronomy Chapters: 9-13 – Flashcards

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