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

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