AY 101 - Test 3

How does the mass of a star affect its lifetime? -More massive stars live slightly longer lives than less massive stars. -More massive stars live slightly shorter lives than less massive stars. -More massive stars live much longer lives than less massive stars. -More massive stars live much shorter lives than less massive stars.

More massive stars live much shorter lives than less massive stars.

A computer accessory salesman attempts to convince you to purchase a "solar neutrino" shield for your new computer. (It's even "on sale"!) Why do you turn down this excellent offer?

Neutrinos rarely, if ever, interact with your computer.

Listed following are events or phenomena that occur during either the part of the sunspot cycle known as solar minimum or the part known as solar maximum. Match these items to the correct part of the sunspot cycle. - auroras are most likely in Earth's skies - orbiting satellites are most at risk - sunspots are most numerous on the Sun - occurs about 5 to 6 years after a solar maximum (on average) - solar flares are most common - occurs about 11 years after a solar maximum (on average)

Solar Maximum: - auroras are most likely in Earth's skies - orbiting satellites are most at risk - sunspots are most numerous on the Sun - solar flares are most common - occurs about 11 years after a solar maximum (on average) Solar Minimum: - occurs about 5 to 6 years after a solar maximum (on average)

Which of the following correctly compares the Sun's energy generation process to the energy generation process in human-built nuclear power plants?

The Sun generates energy by fusing small nuclei into larger ones, while our power plants generate energy by the fission (splitting) of large nuclei.

What do all main sequence stars have in common? - They generate energy through hydrogen fusion in their core. - They are all spectral type G. - They are in the final stage of their lives. - They all have approximately the same mass.

They generate energy through hydrogen fusion in their core

The surface of the Sun bubbles and churns. Why?

We are seeing hot gas rising and cool gas falling due to the convection that occurs beneath the surface

If you returned to our Solar System 10 billion years from now, what would be at the position of our Sun? a neutron star a white dwarf a black hole

a white dwarf

The total amount of power, or energy per time, (in watts, for example) that a star radiates into space is called its _________.

luminosity

Solar energy travels through the convection zone of the Sun in the form of _________________

rising hot gas

What is a planetary nebula? the expanding shell of gas that is left when a white dwarf explodes as a supernova the molecular cloud from which protostars form the expanding shell of gas that is no longer gravitationally bound to the remnant of a low-mass star what is left of its planets after a low-mass star has ended its life a disk of gas surrounding a protostar that may form into planets

the expanding shell of gas that is no longer gravitationally bound to the remnant of a low-mass star

Which of the following best describe the cause of the sunspot cycle? - small variations in the rate of nuclear energy generation in the solar interior - a large change in the amount of visible light emitted by the Sun - a slight gravitational contraction of the Sun - an imbalance in the operation of the solar thermostat - the winding of magnetic field lines due to the Sun's rotation

the winding of magnetic field lines due to the Sun's rotation

Newborn main sequence stars have masses in this range. 0.008 to 100 solar masses 0.08 to 1000 solar masses 0.008 to 10 solar masses 0.08 to 10 solar masses 0.08 to 100 solar masses

0.08 to 100 solar masses

If the distance between us and a star is doubled, with everything else remaining the same, its luminosity 1. remains the same, but its apparent brightness is decreased by a factor of four. 2. is decreased by a factor of two, and its apparent brightness is decreased by a factor of two. 3. remains the same, but its apparent brightness is decreased by a factor of two. 4. is decreased by a factor of four, but its apparent brightness remains the same. 5. is decreased by a factor of four, and its apparent brightness is decreased by a factor of four.

1. remains the same, but its apparent brightness is decreased by a factor of four.

How hot must the core of a star be before hydrogen fusion can begin in a star? 10 trillion K 1 billion K 10 billion K 10,000 K 10 million K

10 million K

At what temperature can helium fusion begin? 100,000 K 100 billion K 10 million K 1 million K 100 million K

100 million K

What event triggers a massive star supernova? 1. helium begins to burn into carbon 2. the iron core collapses into a compact ball of neutrons 3. a planetary nebula is ejected 4. a white dwarf accretes too much material from a companion star

2. the iron core collapses into a compact ball of neutrons

Since all stars begin their lives with more or less the same basic composition, what property most determines how they will differ? 1. color they are formed with 2. luminosity they are formed with 3. mass they are formed with 4. location where they are formed 5. time they are formed

3. mass they are formed with

The net result of fusion in the Sun is that __________.

4 hydrogen nuclei become 1 helium nucleus + energy + 2 neutrinos + 2 positrons

For a high mass main sequence star, which combination of properties go together? 1. Cool, red, dim, long life time 2. Cool, blue, luminous, short life time 3. Hot, red, luminous, long life time 4. Hot, blue, luminous, short life time

4. Hot, blue, luminous, short life time

When a star becomes a red giant, what is its main form of energy generation? 1. helium fusion in the central core 2. hydrogen fusion in the central core 3. gravitational contraction 4. hydrogen fusion in a shell surrounding the central core

4. hydrogen fusion in a shell surrounding the central core

The correct order for the stages of life for a low-mass star are ____________. 1. protostar, main-sequence star, red giant, supernova, neutron star 2. protostar, main-sequence star, planetary nebula, red giant 3. main-sequence star, white dwarf, red giant, planetary nebula, protostar 4. protostar, main-sequence star, red giant, planetary nebula, white dwarf

4. protostar, main-sequence star, red giant, planetary nebula, white dwarf

How long ago was the Sun formed?

4.5 billion years

The Sun has enough nuclear fuel to last another________.

5 billion years

Which of the following comparisons between low-mass stars and high-mass main-sequence stars is true? 1. Low-mass stars are hotter but less luminous than high-mass stars. 2. Low-mass stars have the same temperature and luminosity as high-mass stars. 3. Low-mass stars are hotter and more luminous than high-mass stars. 4. Low-mass stars are cooler but more luminous than high-mass stars. 5. Low-mass stars are cooler and less luminous than high-mass stars.

5. Low-mass stars are cooler and less luminous than high-mass stars.

A star's luminosity is the 1. apparent brightness of the star in our sky. 2. lifetime of the star. 3. total amount of energy that the star will radiate over its entire lifetime. 4. surface temperature of the star. 5. total amount of energy that the star radiates each second.

5. total amount of energy that the star radiates each second.

What is the chemical composition of our Sun?

98%-99% hydrogen and helium, 1-2% heavier elements

Why is a star's birth mass its most important characteristic? - A star's birth mass is the most important predictor of a star's luminosity. A star born with low mass will have a high luminosity; a star born with high mass will have a significantly lower luminosity. - A star's birth mass is the most important predictor of a star's lifetime. A star born with high mass will have a short lifespan; a star born with low mass will have a significantly longer lifespan. - A star's birth mass is the most important predictor of a star's surface temperature. A star born with low mass will have a high surface temperature; a star born with high mass will have a significantly lower surface temperature. - A star's birth mass is the most important predictor of a star's size. A star born with high mass will have a small radius; a star born with low mass will have a significantly greater radius.

A star's birth mass is the most important predictor of a star's lifetime. A star born with high mass will have a short lifespan; a star born with low mass will have a significantly longer lifespan.

What happens to energy in the Sun's convection zone?

Energy is transported outward by the rising of hot gas and falling of cool gas.

Why does the Sun emit neutrinos?

Fusion in the Sun's core creates neutrinos.

Why is iron significant to understanding how a supernova occurs? Iron is the heaviest of all atomic nuclei, and thus no heavier elements can be made. Iron cannot release energy either by fission or fusion. The fusion of iron into uranium is the reaction that drives a supernova explosion. Supernovae often leave behind neutron stars, which are made mostly of iron.

Iron cannot release energy either by fission or fusion

What is the main-sequence turnoff point of a star cluster, and what does it tell us? - It is the point in a star cluster beyond which main sequence stars are not found, and it tells us the cluster's distance. - It is the faintest and coldest main sequence star in a cluster, and it tells us the cluster's age. - It is the spectral type of the hottest main sequence star in a star cluster, and it tells us the cluster's age. - It is the mass of the most massive star in the star cluster, and it tells us the cluster's size.

It is the spectral type of the hottest main sequence star in a star cluster, and it tells us the cluster's age.

Why was special about Supernova 1987A? It was the most distant supernova ever detected. It occurred in our Milky Way Galaxy only a few dozen light-years from Earth. It provided the first observational evidence that supernovae actually occur. It was the nearest supernova detected in nearly 400 years. It provided the first evidence that neutron stars exist.

It was the nearest supernova detected in nearly 400 years.

What is the fate of an isolated brown dwarf? It will become a neutron star. It will remain a brown dwarf forever. It will slowly evaporate to nothing. It will become a white dwarf. It will become a black hole

It will remain a brown dwarf forever.

If an object triples its distance from us, how will the apparent brightness of the object change?

Its apparent brightness will decrease by a factor of 9

Which of the following stars has the coolest surface temperature? an A star an F star an M star

M star

What powers the Sun?

Nuclear fusion

Which star is the hottest star? M G A O Can't tell from information provided.

O

Which of the following stars spends the shortest time on the main sequence? G star B star M star O star

O star

From hottest to coolest, the order of the spectral types of stars is _________. OBAFGKM ABFGKMO OBAGFKM OMKGFBA ABCDEFG

OBAFGKM

What happens when a main-sequence star uses up all of its core hydrogen fuel supply? - The star becomes a neutron star. - The entire star shrinks in size. - The core shrinks while the rest of the star expands. - The core immediately begins to fuse its helium into carbon.

The core shrinks while the rest of the star expands.

The choices below each describe the appearance of an H-R diagram for a different star cluster. Which cluster is the youngest? - The diagram shows no main-sequence stars at all, but it has numerous supergiants and white dwarfs. - The diagram shows main-sequence stars of every spectral type except O, along with a few giants and supergiants. - The diagram shows main-sequence stars of spectral types G, K, and M, along with numerous giants and white dwarfs. - The diagram shows main-sequence stars of all the spectral types except O and B, along with a few giants and supergiants.

The diagram shows main-sequence stars of every spectral type except O, along with a few giants and supergiants.

What does it mean for the Sun to be in gravitational equilibrium?

There is a balance within the Sun between the outward push of gas pressure and the inward pull of gravity.

What common property do sunspots, solar prominences, and solar flares all share?

They are all strongly influenced by magnetic fields on the Sun

Which of the following stars has a spectrum that peaks at the shortest wavelength? a yellow star a red star a blue star

a blue star

Which of the following stars has the longest lifetime? a main-sequence O star a main-sequence G star a main-sequence M star

a main-sequence M star

Which of the following stars is the most massive? a main-sequence O star a main-sequence G star a main-sequence M star

a main-sequence O star

Which of the following stars does not have fusion occurring in its core? a red giant a red main-sequence star a blue main-sequence star

a red giant

What is a protostar? a star in its final stage of life an intermediate-mass star a star that is still in the process of forming a star that has planets

a star that is still in the process of forming

Based on its main-sequence turnoff point, the age of this cluster is less than 1 billion years. about 1 billion years. more than 15 billion years. about 4.5 billion years. about 10 billion years.

about 10 billion years.

What types of stars end their lives with supernovae? all stars that have reached an age of 10 billion years all stars that are at least eight times the mass of the Sun all white dwarf stars all stars that have a similar or less mass than the Sun all stars that have gone through the planetary nebula stage

all stars that are at least eight times the mass of the Sun

A brown dwarf is an object not quite massive enough to be a star a white dwarf that has cooled off a star-like object that is less massive than Jupiter

an object not quite massive enough to be a star

What two quantities are needed to measure a star's luminosity? - apparent brightness and mass - apparent brightness and temperature - apparent brightness and distance

apparent brightness and distance

Why isn't the Sun expanding or shrinking?

because gas pressure balances gravity in the Sun

The ultimate fate of our Sun is to ________. become a rapidly spinning neutron star become a black hole explode in a supernova become a white dwarf that will slowly cool with time

become a white dwarf that will slowly cool with time

Star A is identical to Star B, except that Star A is twice as far from us as Star B. Therefore, ________. - both stars have the same apparent brightness, but the luminosity of Star B is four times that of Star A - both stars have the same luminosity, but the apparent brightness of Star B is four times that of Star A - both stars have the same luminosity, but the apparent brightness of Star A is four times that of Star B - both stars have the same luminosity, but the apparent brightness of Star B is twice that of Star A

both stars have the same luminosity, but the apparent brightness of Star B is four times that of Star A

On an H-R diagram, stellar masses _________. - can be estimated for main sequence stars but not for other types of stars - increase from upper left to lower right - are impossible to determine - are greatest in the lower left and least in the upper right

can be estimated for main sequence stars but not for other types of stars

Helium fusion results in the production of carbon. iron. hydrogen. oxygen. nitrogen.

carbon

What causes the cycle of solar activity? - changes in the Sun's fusion rate - changes in the speed of the solar wind - changes in the organization of the Sun's magnetic field

changes in the organization of the Sun's magnetic field

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

chromosphere

Stars form best in clouds that are cold and dense warm and dense hot and low-density

cold and dense

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

convection zone

Nuclear fusion of hydrogen into helium occurs in the ____________

core

List the layers of the Sun starting at the center and working outward.

core, radiation zone, convection zone, photosphere, chromosphere, corona

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

corona

Which of following has the greatest mass? - a helium nucleus - four separate hydrogen nuclei added together - actually, a helium nucleus and four separate hydrogen nuclei have the same mass

four separate hydrogen nuclei added together

If the star Alpha Centauri were moved to a distance 10 times farther than it is now, its parallax angle would

get smaller

At the center of the Sun, fusion converts hydrogen into

helium, energy, and neutrinos

Which part of the electromagnetic spectrum generally gives us our best views of stars forming in dusty clouds? infrared ultraviolet blue light visible light

infared

The Sun converts 600 million tons of hydrogen into 596 million tons of helium every second. What happens to the remaining 4 million tons of mass?

it is converted to an amount of energy equal to 4 million tons times the speed of light squared

Which key quantity of a star determines if it will eventually fuse oxygen into a heavier element in its core? - how much oxygen it now has in its core - its mass - its overall abundance of elements heavier than helium - its luminosity

its mass

Most stars in a newly formed star cluster are ________. less massive than the Sun about the same mass as our Sun red giants very high-mass, type O and B stars

less massive than the sun

On a Hertzsprung-Russell diagram, where are white dwarfs? upper right lower right upper left lower left

lower left

Which of the following represents the correct sequence of life events for a high mass star? red supergiant, main sequence, supernova, neutron star main sequence, red supergiant, neutron star, supernova main sequence, red supergiant, supernova, neutron star red supergiant, main sequence, neutron star, supernova

main sequence, red supergiant, supernova, neutron star

After a massive star supernova explosion, the remains of the stellar core ________. may be either a neutron star or a black hole will always be a neutron star will always be a black hole may be either a white dwarf, neutron star, or black hole

may be either a neutron star or a black hole

The core of the Sun is ______ - constantly rising to the surface through convection. - much hotter and much denser than its surface. - composed of iron. - at the same temperature and density as its surface. - at the same temperature but much denser than its surface.

much hotter and much denser than its surface.

By what process do nuclear power plants on the Earth generate energy?

nuclear fission

In what part of the Sun do fusion reactions happen

only the core

What two quantities do we need to calculate the masses of stars in a binary system? absolute magnitudes and luminosities orbital period and average orbital distance spectral types and distance from Earth luminosities and distance from Earth

orbital period and average orbital distance

Nearly all the visible light we see from the Sun is emitted from the ___________________

photosphere

The Sun's surface is called the ________.

photosphere

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

radiation zone

Why do we not expect stars to form with masses larger than 100 times our Sun? they would generate so much radiation pressure that they would blow themselves apart. they would shine exclusively at X-ray wavelengths and would be difficult to detect. molecular clouds do not have enough material to form such massive stars. they would be too massive for hydrogen fusion to occur in their cores. they would fragment into binary stars because of their rapid rotation.

they would generate so much radiation pressure that they would blow themselves apart.

The overall helium fusion reaction is ________. two hydrogen nuclei fuse to form one helium nucleus three helium nuclei fuse to form one carbon nucleus two helium nuclei fuse to form one beryllium nucleus four helium nuclei fuse to form one oxygen nucleus

three helium nuclei fuse to form one carbon nucleus

On a Hertzsprung-Russell diagram, where on the main sequence do the stars with the greatest mass reside? upper right lower right upper left lower left

upper left

In which part of the electromagnetic spectrum is the Sun emitting most of its energy from its surface?

visible