question

How does the radius of the event horizon change when you ass a mass to a black hole

answer

It Increases

question

O B A F G K M TEMPERATURE

answer

Hottest -Coldest

question

O B A F G K M mass

answer

Most Massive - Least Massive

question

What do we mean by the main-sequence turnoff point of a star cluster, and what does it tell us?

answer

-It is the spectral type of the hottest main sequence star in a star cluster -cluster's age

question

A brown dwarf is

answer

an object not quite massive enough to be a star

question

Careful measurements reveal that a star maintains a steady apparent brightness at most times, except that at precise intervals of 73 hours the star becomes dimmer for about 2 hours. The most likely explanation is that

answer

the star is a member of an eclipsing binary star system

question

O B A F G K M which stars are cool and dim?

answer

K M

question

Which group represents stars of the largest radii? o b a f g k m

answer

F G K M

question

hich group represents stars that are extremely bright and emit most of their radiation as ultraviolet light

answer

O B

question

Which group represents stars with the longest main-sequence lifetimes

answer

K M

question

Which group represents stars fusing hydrogen in their cores?

answer

...

question

Which group represents stars fusing hydrogen in their cores?

answer

Entire main sequence

question

You observe a star and you want to plot it on an H-R diagram. You will need to measure all of the following, except the star's ________

answer

Mass

question

How did astronomers discover the relationship between spectral type and mass for main sequence stars

answer

By measuring the masses and spectral types of main-sequence stars in binary systems

question

What is the approximate range of masses that newborn main sequence stars can have?

answer

0.1 to 150 solar masses

question

Which of the following lists the stages of life for a low-mass star in the correct order

answer

Protostar, main-sequence star, red giant, planetary nebula, white dwarf

question

Why is iron significant to understanding how a supernova occurs?

answer

Iron cannot release energy either by fission or fusion.

question

Algol consists of a 3.7 M Sun main-sequence star and a 0.8 M Sun subgiant. Why does this seem surprising, at least at first

answer

The two stars should be the same age, so we'd expect the subgiant to be more massive than the main-sequence star.

question

What is a protostar

answer

A star that is still in the process of forming

question

Approximately what core temperature is required before hydrogen fusion can begin in a star?

answer

10 million K

question

The vast majority of stars in a newly formed star cluster are ________.

answer

Less massive than the Sun

question

What is a planetary nebula?

answer

Gas ejected from a low-mass star in the final stage of its life

question

he ultimate fate of our Sun is to ______

answer

Become a white dwarf and cool in time

question

After a supernova explosion, the remains of the stellar core _____

answer

may be either a neutron star or a black hole

question

The Schwarzschild radius of a black hole depends on ________.

answer

only the mass of the black hole

question

The maximum mass of a white dwarf is _________

answer

about 1.4 times the mass of our Sun

question

A neutron star is ________

answer

the remains of a star that died in a massive star supernova (if no black hole was created)

question

Pulsars are thought to be ________

answer

rapidly rotating neutron stars

question

what is the basic definition of a black hole

answer

An object with gravity so strong that not even light can escape

question

At the center of the Sun, fusion converts hydrogen into

answer

helium, energy, and neutrinos

question

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

answer

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

question

Which of the following best explains why nuclear fusion requires bringing nuclei extremely close together?

answer

Nuclei normally repel because they are all positively charged and can be made to stick only when brought close enough for the strong force to take hold.

question

What do we need to measure in order to determine a star's luminosity?

answer

apparent brightness and distance

question

What two pieces of information would you need in order to measure the masses of stars in an eclipsing binary system?

answer

the time between eclipses and the average distance between the stars

question

Which of these stars has the coolest surface temperature? A F K

answer

K

question

Which of these stars is the most massive? A G M

answer

A

question

Which of these stars has the longest lifetime A G M

answer

M

question

Which of these stars has the largest radius? A K M

answer

M

question

Star A is identical to Star B, except that Star A is twice as far from us as Star B. Therefore:

answer

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

question

true or false The spectral type of a star can be used to determine its distance.

answer

False

question

Sirius is a star with spectral type A star and Rigel is a star with spectral type B star. What can we conclude about temperature?

answer

Rigel has a higher surface temperature than Sirius

question

To calculate the masses of stars in a binary system, we must measure their ________.

answer

orbital period and average orbital distance

question

Why is a sunflower yellow?

answer

It reflects yellow light.

question

Blue light has higher frequency than red light. Thus, blue light has:

answer

higher energy and shorter wavelength than red light.

question

Radio waves are a form of sound a form of light. a type of spectrum.

answer

a form of light.

question

The set of spectral lines that we see in a star's spectrum depends on the star's:

answer

chemical composition.

question

A star whose spectrum peaks in the infrared is

answer

cooler than our Sun.

question

A spectral line that appears at a wavelength of 321nm in the laboratory appears at a wavelength of 328nm in the spectrum of a distant object. We say that the object's spectrum is redshifted. blueshifted. skewed.

answer

redshifted.

question

The Hubble Space Telescope obtains higher-resolution images than most ground-based telescopes because it is: Larger. closer to the stars. above Earth's atmosphere

answer

Larger

question

True or False green grass absorbs red light and reflects green light.

answer

True

question

True Or False X-rays travel through space faster than radio waves.

answer

False

question

Studying a spectrum from a star can tell us a lot. All of the following statements are true except one. Which statement is not true?

answer

The total amount of light in the spectrum tells us the star's radius

question

The angular separation of two stars is 0.1 arcseconds and you photograph them with a telescope that has an angular resolution of 1 arcsecond. What will you see

answer

The photo will seem to show only one star rather than two

question

How does the light-collecting area of an 8-meter telescope compare to that of a 2-meter telescope?

answer

The 8-meter telescope has 16 times the light-collecting area of the 2-meter telescope.

question

Which of the following is not an advantage of the Hubble Space Telescope over ground-based telescopes?

answer

It is closer to the stars.

question

The Chandra X-ray Observatory must operate in space because

answer

X-rays do not penetrate Earth's atmosphere

question

Which of the following is always true about images captured with X-ray telescopes?

answer

They are always shown with colors that are not the true colors of the objects that were photographed.

question

How are wavelength, frequency, and energy related for photons of light?

answer

Longer wavelength means lower frequency and lower energy.

question

According to modern science, approximately how old is the Sun?

answer

4.5 billion years

question

From center outward, which of the following lists the "layers" of the Sun in the correct order?

answer

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

question

The overall result of the proton-proton chain is that __________

answer

4 H becomes 1 He + energy

question

The Sun will exhaust its nuclear fuel in about ________.

answer

5 billion years

question

The source of energy that keeps the Sun shining today is ________.

answer

nuclear fusion

question

The Sun's surface, as we see it with our eyes, is called the ______

answer

photosphere

question

The Sun's average surface (photosphere) temperature is about ________.

answer

5,800 K

question

What is the solar wind?

answer

A stream of charged particles flowing outward from the surface of the Sun

question

A stream of charged particles flowing outward from the surface of the SunThe fundamental nuclear reaction occurring in the core of the Sun is ______

answer

Nuclear fusion of hydrogen into helium

question

According to the inverse square law of light, how will the apparent brightness of an object change if its distance to us triples?

answer

Its apparent brightness will decrease by a factor of 9.

question

Assuming that we can measure the apparent brightness of a star, what does the inverse square law for light allow us to do?

answer

Calculate the star's luminosity if we know its distance, or calculate its distance if we know its luminosity.

question

he axes on a Hertzsprung-Russell (H-R) diagram represent _________

answer

Luminosity and surface temperature

question

What do we mean by the main-sequence turnoff point of a star cluster, and what does it tell us?

answer

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

question

What would you be most likely to find if you returned to the solar system in 10 billion years? a neutron star a white dwarf a black hole

answer

a white dwarf

question

In order to predict whether a star will eventually fuse oxygen into a heavier element, you mainly want to know what fact about the star?

answer

its mass

question

Our Sun is considered to be a ________. intermediate-mass star brown dwarf low-mass star high-mass star

answer

low-mass star

question

what is the heaviest element that a 10 solar mass star will create in its core?

answer

iron

question

Where was the majority o the golf on earth created?

answer

Supernova

question

What is the upper mass limit of a neutron star Most massive a nuestron star could be

answer

3 Solar masses

question

Which of the follwing has the smallest radius

answer

the event horizon of a 3.0 solar mass black hole adding mass to black hole makes for larger radius adding mass to star means smaller radius

question

someone is signaling you with a green laser from just outside of the event horizon of a black hole What do you see? red light greenlight blue light

answer

red light

question

List in they correct order of phases for a 1 solar mass star going from birth to death

answer

Prostar main sequnce giant planetary nebula white dwarf

question

White dwarfs are typically made up of what material

answer

Carbon

question

Which process compltey destroys the star leaving nothing behind?

answer

White dwarf supernova

question

HOw does a Red GIant star look different from a main Sequence star of simalar mass?

answer

Redder & Brighter

question

which of these stars are the oldest? A Temp 22,000 B Temp 9,000 C Temp 5,000 D Temp 7,000

answer

C (the older the star the cooler the star)

question

Where would a brown dwarf be located on an H-R diagram?

answer

Below and to the right of the lowest part of the main sequence

question

Carbon fusion occur in high-mass stars but not in low-mass stars because ________

answer

the cores of low-mass stars never get hot enough for carbon fusion

question

Which event marks the beginning of a supernova?

answer

collapse of an iron core into a ball of neutrons

question

A spinning neutron star has been observed at the center of a ________.

answer

supernova remnant

question

Which is more common: a star blows up as a supernova, or a star forms a planetary nebula/white dwarf system?

answer

Planetary nebula formation is more common.

question

You discover a binary star system in which one star is a 15 MSun main-sequence star and the other is a 10 MSun giant. How do we think that a star system such as this might have come to exist?

answer

The giant must once have been the more massive star, but is now less massive because it transferred some of its mass to its companion.

question

What did Carl Sagan mean when he said that we are all "star stuff"?

answer

that the carbon, oxygen, and other elements essential to life were created by nucleosynthesis in stellar cores

question

Compared to the star it evolved from, a red giant is

answer

cooler and brighter.

question

What happens to the core of a star after it ejects a planetary nebula?

answer

It becomes a white dwarf.

question

Compared to the star it evolved from, a newly formed white dwarf is

answer

hotter and dimmer.

question

What types of stars end their lives with supernovae?

answer

stars that are at least several times the mass of the Sun

question

After a supernova event occurring in a high-mass star, what is left behind?

answer

either a neutron star or a black hole

question

A typical white dwarf is _________.

answer

as massive as the Sun but only about as large in size as Earth

question

Which of these objects has the smallest radius?

answer

a 1.2 white dwarf

question

Suppose that a white dwarf is gaining mass through accretion in a binary system. What happens if the mass someday reaches the 1.4 solar mass limit?

answer

The white dwarf will explode completely as a white dwarf supernova.

question

A typical neutron star is more massive than our Sun and about the size (radius) of _________.

answer

a small asteroid (10 km in diameter)

question

What do we mean by the event horizon of a black hole?

answer

It is the point beyond which neither light nor anything else can escape.

question

Imagine that our Sun were magically and suddenly replaced by a black hole of the same mass (1 solar mass). What would happen to Earth in its orbit?

answer

Nothing—Earth's orbit would remain the same.

question

Which of these objects has the largest radius? a 1.2 white dwarf a 1.5 neutron star a 3.0 black hole

answer

a 1.2 white dwarf

question

Which of these things has the smallest radius? a 1.2 white dwarf the event horizon of a 3 black hole the event horizon of a 10 black hole

answer

the event horizon of a 3 black hole

question

How would a flashing red light appear as it fell into a black hole?

answer

Its flashes would shift to the infrared part of the spectrum.

question

Which of these black holes exerts the weakest tidal forces on an object near its event horizon? 10 black hole 100 black hole 10^6 black hole

answer

10^6 black hole

question

The more massive a white dwarf, the ________.

answer

smaller its radius

question

The white dwarf that remains when our Sun dies will be mostly made of ________.

answer

carbon

question

Will our Sun ever undergo a white dwarf supernova explosion? Why or why not?

answer

No, because it is not orbited by another star.

question

Which of the following best describes what would happen if a 1.5-solar-mass neutron star, with a diameter of a few kilometers, were suddenly (for unexplained reasons) to appear in your home town?

answer

The entire Earth would end up as a thin layer, about 1 cm thick, over the surface of the neutron star.

question

Which statement concerning black hole masses and Schwarzschild radii is not true?

answer

In a binary system with a black hole, the Schwarzschild radius depends on the distance from the black hole to the companion star.

question

Suppose you drop a clock toward a black hole. As you look at the clock from a high orbit, what will you notice?

answer

Time on the clock will run slower as it approaches the black hole, and light from the clock will be increasingly redshifted.

question

Suppose you know the frequency of a photon and the speed of light. What else can you determine about the photon?

answer

its wavelength and energy

question

Which of the following best describes the fundamental difference between two different chemical elements (such as oxygen and carbon)?

answer

They have different numbers of protons in their nucleus.

question

Suppose you watch a leaf bobbing up and down as ripples pass it by in a pond. You notice that it does two full up and down bobs each second. what is its frequency?

answer

They have a frequency of 2 hertz.

question

If we say that a material is opaque to ultraviolet light, we mean that it _________.

answer

absorbs ultraviolet light

question

Which forms of light are lower in energy and frequency than the light that our eyes can see?

answer

infrared and radio

question

Suppose you look at a spectrum of visible light by looking through a prism or diffraction grating. How can you decide whether it is an emission line spectrum or an absorption line spectrum?

answer

emission bright lines on a dark background absorption dark lines on a rainbow background.

question

Thermal radiation is defined as _________.

answer

radiation with a spectrum whose shape depends only on the temperature of the emitting object

question

According to the laws of thermal radiation, hotter objects emit photons with _________.

answer

a shorter average wavelength

question

Suppose you want to know the chemical composition of a distant star. Which piece of information is most useful to you?

answer

the wavelengths of spectral lines in the star's spectrum

question

The spectra of most galaxies show redshifts. This means that their spectral lines _________.

answer

have wavelengths that are longer than normal

question

the two principle advantages of telescopes over eyes?

answer

Telescopes can collect far more light with far better angular resolution.

question

The stars in our sky twinkle in brightness and color because of _________.

answer

turbulence in Earth's atmosphere

question

From shortest to longest wavelength, which of the following correctly orders the different categories of electromagnetic radiation?

answer

Gamma rays, X-rays, ultraviolet, visible light, infrared, radio

question

When considering light as made up of individual "pieces," each characterized by a particular amount of energy, the pieces are called ________.

answer

photons

question

Visible light from a distant star can be spread into a spectrum by using a glass prism or ________.

answer

a diffraction grating

question

An atom that has fewer electrons than protons is called a/an ________.

answer

ion

question

What is the angular resolution of the human eye?

answer

About 1 arcminute, or 1/60 of a degree

question

What do astronomers mean by light pollution?

answer

Light pollution is light from human sources that makes it difficult to see the stars at night.

question

What is the purpose of adaptive optics?

answer

reduces blurring caused by atmospheric turbulence

question

What is the purpose of interferometry?

answer

It allows two or more small telescopes to achieve the angular resolution of a much larger telescope.

question

Fission is?

answer

BIg nucleus splits into 2 smaller piecies Neclear power plants

question

Fusion is?

answer

Small nuclei stick together to make a bigger one SUN AND STARS

question

A stars Brightness depends on?

answer

Luminisoity and Distance

question

mass determines?

answer

how hot a star gets what element it will produce

question

Iron core of massive star reaches white dwarf limit and collapses into a neutron star, causing an explosion.

answer

Massive star supernova:

question

White dwarf in close binary system reaches white dwarf limit causing

answer

a total explosion

question

In the Greek geocentric model, the retrograde motion of a planet occurs when:

answer

the planet actuall goes backwards in its orbit to earth

question

Keplers laws of motion

answer

First law the orbit of each planets around the sun is an ellipse with the sun at one focus ----- basically a planets distance from the sun changes depending on its orbit Second law as a planet moves around its orbit it sweeps out equal areas in equal times ----- This means that a planet travels faster when it's nearer to the sun and slower when it us farther from the sun Third law more distant planets orbit the sun at slower average speeds obeying the relationships ---- uses a mathematical equation to prove that more distant planets move more slowly Kepler was led to believe that planetary motions were a result of force of the sun .

question

Galileo observed all of the following. Which observation offered direct proof of a planet orbiting the Sun?

answer

Phases of venus

question

One of the "nails in the coffin" for the Earth-centered universe was

answer

Galileo's observations of the moons of Jupiter.

question

From Kepler's third law, a hypothetical planet that is twice as far from the Sun as Earth should have a period of

answer

More than 2 years

question

Kepler's second law, which states that as a planet moves around its orbit it sweeps out equal areas in equal times, means that

answer

planets travel faster when nearer to the sun and slower when further

question

Which one of the following describes an object that is accelerating?

answer

A car going around a circular track at a steady 100 miles per hour.

question

Compared to its angular momentum when it is farthest from the Sun, Earth's angular momentum when it is nearest to the Sun is

answer

the same

question

The gravitational potential energy of a contracting interstellar cloud:

answer

gradually transforms into other forms of energy.

question

If the Moon were closer to Earth, high tides would:

answer

be higher than they are now.

question

Which of the following best describes the origin of ocean tides on Earth?

answer

Tides are caused by the difference in the force of gravity exerted by the Moon across the sphere of the Earth.

question

According to the universal law of gravitation, if you double the masses of both attracting objects, then the gravitational force between them will

answer

increase by a factor of four

question

The gravitational force that the Earth exerts on the Moon is equal and opposite to that which the Moon exerts on the Earth. Therefore, according to Newton's second law of motion,

answer

the Moon as a larger acceleration than the Earth, because it has a smaller mass.

question

What is the celestial sphere?

answer

The celestial sphere is a representation of how the entire sky looks as seen from Earth.

question

What is the ecliptic?

answer

The path the Sun appears to trace around the celestial sphere each year

question

Which of the following statements does not use the term angular size or angular distance correctly?

answer

The angular distance between those two bright stars in the sky is about 2 meters.

question

The point directly over your head is called ________.

answer

the zenith

question

Which kind of object is the best standard candle for measuring distances to extremely distant galaxies?

answer

a white dwarf supernova

question

Why do virtually all the galaxies in the universe appear to be moving away from our own?

answer

Because expansion causes all galaxies to move away from nearly all others.

question

Which of these galaxies is most likely to be oldest?

answer

a galaxy in the Local Group

question

When we observe a distant galaxy whose photons have traveled for 10 billion years before reaching Earth, we are seeing that galaxy as it was when the universe was

answer

4 billion years old.

question

In a photo like the Hubble Deep Field (the figure in your textbook), we see galaxies in many different stages of their lives. In general, which galaxies are seen in the earliest (youngest) stages of their lives?

answer

The galaxies that are farthest away

question

The most basic difference between elliptical galaxies and spiral galaxies is that ________.

answer

elliptical galaxies lack anything resembling the disk of a spiral galaxy

question

Hubble's galaxy classification diagram (the "tuning fork") ________.

answer

relates galaxies according to their shapes, but not according to any evolutionary status

question

Suppose we observe a Cepheid variable in a distant galaxy. The Cepheid brightens and dims with a regular period of about 10 days. What can we learn from this observation?

answer

We can learn the distance to the galaxy.

question

In 1924, Edwin Hubble proved that the Andromeda Galaxy lay far beyond the bounds of the Milky Way, thus putting to rest the idea that it might have been a cloud within our own galaxy. How was he able to prove this?

answer

By observing individual Cepheid variable stars in Andromeda and applying the period-luminosity relation

question

Why are white dwarf supernovae more useful than massive star supernovae for measuring cosmic distances?

answer

White dwarf supernovae all have roughly the same true peak luminosity, while massive supernovae come in a wide range of peak luminosities.

question

What is the best way to determine a galaxy's redshift?

answer

Take a spectrum of the galaxy, and measure the difference in wavelength of spectral lines from the wavelengths of those same lines as measured in the laboratory.

question

Which statement below correctly describes the relationship between expansion rate and age for the universe?

answer

The faster the rate of expansion, the younger the age of the universe.

question

What does cosmological redshift do to light?

answer

Stretches its wavelength

question

What does Hubble's law tell us?

answer

The more distant a galaxy, the faster it is moving away from us.

question

If we say that a galaxy has a lookback time of 1 billion years, we mean that ________.

answer

its light traveled through space for 1 billion years to reach us

question

Current estimates place the age of the universe at about ________.

answer

14 billion years

question

According to current understanding, what is a quasar?

answer

An active galactic nucleus that is particularly bright

question

The mass of a supermassive black hole thought to power a typical bright active galactic nucleus is roughly ________.

answer

1 billion solar masses

question

What is the most accurate way to determine the distance to a nearby star?

answer

stellar parallax

question

What is the most accurate way to determine the distance to a nearby galaxy?

answer

Cepheid variables

question

Which of the following best summarizes what we mean by dark matter?

answer

matter that we have identified from its gravitational effects but that we cannot see in any wavelength of light

question

Which of the following best summarizes what we mean by dark energy?

answer

It is a name given to whatever is causing the expansion of the universe to accelerate with time.

question

What is a rotation curve?

answer

a graph showing how orbital velocity depends on distance from the center for a spiral galaxy

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