Astronomy Chapter 9 Quiz

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Questions and Answers

What is the primary energy source for a star while on the main sequence?

Nuclear fission

Magnetic fields

Gravitational potential energy

Nuclear fusion (correct)

Why cannot the lowest-mass stars become giants?

They contain strong magnetic fields

They cannot heat their centers hot enough (correct)

They do not contain helium

They rotate too slowly

What defines a planetary nebula?

A nebula within which planets are forming

A cloud of hot gas surrounding a planet

Produced by a supernova explosion

The expelled outer envelope of a medium mass star (correct)

What does the Chandrasekhar limit indicate?

White dwarfs must contain more than 1.4 solar masses Signup and view all the answers

What happens to the energy emitted by a white dwarf?

Not replaced Signup and view all the answers

Which event triggers a Type I supernova?

A white dwarf exceeds the Chandrasekhar limit Signup and view all the answers

What is usually associated with a nova event?

A white dwarf in a close binary system Signup and view all the answers

What occurs as material leaves an expanding star and begins to fall into a white dwarf?

An accretion disk will form around the white dwarf Signup and view all the answers

What characteristic differentiates giant stars from the sun?

They have a larger absolute magnitude than the sun. Signup and view all the answers

Which of the following statements is true about giant stars?

Giant stars are located above main sequence stars in the H-R diagram. Signup and view all the answers

Which star depicted in the H-R diagram is least similar to the sun?

Alnilam Signup and view all the answers

From the provided H-R diagram, which star possesses the highest surface temperature?

Alnilam Signup and view all the answers

Which star has the largest radius according to the H-R diagram?

Antares Signup and view all the answers

In the H-R diagram, where are stars with the smallest radius located?

Lower left corner Signup and view all the answers

What can be determined from observing an eclipsing binary star?

The masses and sizes of the individual stars. Signup and view all the answers

Doppler shift observations of a spectroscopic binary star are useful to calculate what?

The masses of the individual stars. Signup and view all the answers

What happens to the pitch of a train's horn as it approaches and moves away from an observer?

The pitch gets higher as it approaches and lower as it moves away. Signup and view all the answers

Which star from the list has the lowest temperature?

o Cet (M7) Signup and view all the answers

Which star from the list has the highest spectral type indicating the highest temperature?

ɸ Per (O7) Signup and view all the answers

What is the proper order of star colors according to increasing temperature?

Red, Yellow, Blue Signup and view all the answers

What effect does the Doppler effect have on the motion of objects in space?

It shifts the wavelength of spectral lines. Signup and view all the answers

Which star is considered the hottest based on its spectral classification?

B5 Signup and view all the answers

Under what condition may interstellar gas clouds collapse to form stars?

They encounter a shock wave. Signup and view all the answers

On an HR diagram, the main sequence is represented by a specific line. What does this line indicate?

The luminosity of the stars. Signup and view all the answers

Which method helps in detecting binary stars?

One star dimming abruptly as another passes in front Signup and view all the answers

What can be used to determine the mass of a visual binary star pair?

The time it takes for them to orbit each other Signup and view all the answers

What distinguishes the white dwarf star Sirius B's mass as comparable to the Sun's?

Its relationship in a binary star system Signup and view all the answers

Where do 90 percent of all stars lie on the Hertzsprung-Russell diagram?

On the main sequence Signup and view all the answers

If two identical stars are emitting the same amount of light, how will their brightness be perceived if one is farther away?

The closer star will appear brighter Signup and view all the answers

What indicates that some stars are relatively close to Earth?

Some stars are occasionally eclipsed by the Moon Signup and view all the answers

What characteristic is always true for stars in the upper right part of the Hertzsprung-Russell diagram compared to those in the middle?

They are brighter Signup and view all the answers

What auditory change is experienced as a train approaches while blowing its horn?

The horn sounds lower in pitch as it nears Signup and view all the answers

Which labeled location on the HR diagram indicates a luminosity and temperature similar to that of a T Tauri star?

Location 4 Signup and view all the answers

What initiates the free-fall contraction of a molecular cloud?

Shock waves from supernovae Signup and view all the answers

Why does the proton-proton chain need high temperature to function?

To overcome the Coulomb barrier Signup and view all the answers

What process in massive stars on the main sequence involves the thermonuclear fusion of hydrogen into helium?

The CNO cycle Signup and view all the answers

What is the minimum temperature required at the center of the sun for it to produce energy through the proton-proton chain?

107 K Signup and view all the answers

Which statement about the carbon-nitrogen-oxygen cycle is correct?

It combines four hydrogen nuclei to form one helium nucleus, producing energy. Signup and view all the answers

What occurs in the region of the sun just below the photosphere?

Thermonuclear fusion using the CNO cycle Signup and view all the answers

What characterizes the central cores of massive main sequence stars?

They experience a rapid increase in temperature Signup and view all the answers

Why do neutron stars spin rapidly?

They conserved angular momentum when they collapsed. Signup and view all the answers

What makes neutron stars difficult to locate despite their high temperatures?

They have small surface areas. Signup and view all the answers

What is produced when electrons fuse with protons at extremely high densities and temperatures?

Neutrons and neutrinos. Signup and view all the answers

Which statement correctly describes the density relationship between a pulsar and a white dwarf?

The density of a pulsar is greater than that of a white dwarf. Signup and view all the answers

What requirements must a neutron star meet to be classified as a pulsar?

Must rotate rapidly and have a strong magnetic field. Signup and view all the answers

What does the event horizon signify in a black hole?

It has a radius equal to the Schwarzschild radius. Signup and view all the answers

Why would an isolated black hole be difficult to detect in space?

Very little matter would be falling into it. Signup and view all the answers

What is involved in the search for black holes?

Finding x-ray binaries with a compact companion exceeding 3 solar masses. Signup and view all the answers

Study Notes

Multiple Choice Questions - Astronomy Chapter 9

Giant stars are larger in diameter than the Sun because they are more luminous but have about the same temperature.
Giant stars are more luminous than the Sun, larger in diameter than the Sun, and cooler than B stars. They are located above the main sequence stars in the H-R diagram.
The star in the HR diagram most similar to the Sun is Arcturus.
The star with the highest surface temperature in the HR diagram is Alnilam.
The star with the largest radius in the HR diagram is Antares.
In an H-R diagram, stars with the smallest radius are found in the lower left corner.
Spectroscopic and eclipse duration observations of an eclipsing binary star can enable astronomers to calculate the masses and sizes of its individual stars.
Doppler shift observations of a spectroscopic binary star can enable astronomers to calculate the masses of its individual stars.
Binary (double) stars can be detected by being seen as two separate stars with a telescope, one star traveling a wiggly proper motion path across the sky, one star dimming abruptly as another passes in front of it, or pairs of absorption lines seen in the spectrum of what appears to be one star.
The mass of a visual binary pair of stars can be obtained from the time in years for them to orbit one another and their size/locations in space.
White dwarf stars have a mass comparable to the Sun because of their measured temperature compared to other stars, especially Sirius A, a component of a binary star system.
In the H-R diagram, 90 percent of stars are on the main sequence.
Main sequence stars are the most common stars.
If two stars emit the same light, the farther star will appear dimmer.
Some stars appear to move periodically back and forth because of the Earth's movement around the Sun.
Stars in the upper right of the Hertzsprung-Russell diagram are always larger than stars near the diagram's middle.
As a train approaches, its horn sounds higher in pitch than when it is moving away.
The star labeled o Cet in the table has the lowest temperature.
The star labeled o Cet in the table has the highest temperature.
The colors of stars in order of increasing temperature are Red, Yellow, Blue.
The Doppler effect states that the motion of any object can shift the wavelength of spectral lines.

Additional Topics

Interstellar gas clouds may collapse to form stars if they encounter a shock wave. A T Tauri star is shown as a location on an HR diagram that indicates luminosity and temperature similar to that of a T Tauri star.
The free-fall contraction of a molecular cloud can be initiated by shock waves from supernovae or nearby spectral type G stars.
The proton-proton chain needs high temperature because the protons must overcome the Coulomb barrier.
The CNO cycle is the thermonuclear fusion of hydrogen to form helium operating in the cores of massive stars on the main sequence.
If the Sun produces energy by the proton-proton chain, then the Sun's center must have a temperature of at least 107 K.
The carbon-nitrogen-oxygen (CNO) cycle operates at a lower temperature than the proton-proton chain and combines four hydrogen nuclei to form one helium nucleus.
The central cores of massive main sequence stars transmit energy outward by convection.
Stars on the main sequence derive their energy from nuclear fusion.
The lowest-mass stars cannot become giants because they cannot heat their centers hot enough.
A planetary nebula is the expelled outer envelope of a medium mass star.
The Chandrasekhar limit is 1.4 solar masses.
The energy a white dwarf emits into space is not replaced through fusion.
A Type I supernova occurs when a white dwarf exceeds the Chandrasekhar limit, and it is often associated with a carbon detonation.
A nova involves a white dwarf in a close binary system.
Material that accretes onto a neutron star or black hole emits x-rays because the material heats up and converts thermal energy to gravitational potential.
The singularity of a black hole is located at the center of the event horizon.
The escape velocity at the event horizon of a black hole is greater than the speed of light.

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Description

Test your knowledge on giant stars and their characteristics in this Astronomy Chapter 9 quiz. Explore concepts related to the H-R diagram, binary stars, and how astronomers calculate star properties. Perfect for students studying stellar evolution and classification.