astronomy chp 12 & 13 hw

This image shows a low-mass star shedding its outer layer. What happens during this process?

-A planetary nebula is created. -The star becomes a white dwarf.

How does the energy production in a high-mass, main-sequence star differ from energy production in the Sun?

-High-mass stars produce energy at a faster rate. -High-mass stars use carbon in a process that fuses hydrogen to helium.

Suppose Jupiter were not a planet, but instead were a G5 main-sequence star with a mass of 0.8 Msun. How could this affect the Sun as the G5 star came to the end of its life?

-The Sun would have already become a white dwarf, and as the G5 swelled into a red giant, material from it would be transferred to an accretion disk around the Sun, making the Sun explode as a nova. -The G5 may have transferred all its mass to the Sun, causing the Sun to explode as a Type 1 supernova.

The following images represent different evolutionary stages of a post-main-sequence star of 1 Msun. Place them in chronological order.

1. Red giant star 2. He flash 3. H. branch star 4. AGB star 5. Nebula ejection 6. White dwarf

Place the following steps that lead some low-mass stars in binary systems to become novae or supernovae in the correct order.

1. Star 1 (the more massive star) begins to evolve off the main sequence. 2. Star 1 fills its Roche lobe and begins transferring mass to star 2. 3. Star 2 gains mass, becoming hotter and more luminous. 4. A white dwarf orbits a more massive main-sequence star. 5. Star 2 fills its Roche lobe and begins transferring mass to the white dwarf. 6. The white dwarf becomes either a nova or a supernova.

While on the main sequence, a star is stable because there is a balance between its self-gravity trying to make the star collapse in on itself and the outward pressure of the gas heated by nuclear fusion is trying to make it expand. When the core of a star runs out of fuel and nuclear fusion stops, what will happen to the star?

It will collapse.

Stars are defined to be on the main sequence if they are burning hydrogen in their cores (hydrogen is combining into helium through nuclear fusion). Eventually, a star will run out of hydrogen fuel in its core, nuclear fusion will stop, and the star will enter a new stage of its lifetime. Examine the table here, and use what you learn from it to chose the correct statement.

More massive stars emit less energy and run out of hydrogen fuel in their cores faster.

Which of the following statements about massive stars having the shortest lifetimes is not true?

The higher a star's mass, the greater the percent of heavier elements from which it formed, and heavier elements burn hotter and faster.

Which of the following stars will have the longest lifetime?

a star 1/20 as massive of the Sun

Iron fusion cannot support a star because iron

absorbs energy when it fuses.

If the Sun were replaced by a 1-solar-mass black hole,

all objects in the Solar System would remain in their orbits.

A white dwarf will become a supernova if

enough mass accretes from a companion to give the white dwarf a total mass of 1.38 Msun.

If a neutron star is more than three times as massive as the Sun, it collapses because

gravity overpowers the force of neutron degeneracy.

As the mass of a black hole increases, its Schwarzschild radius

increases proportionally.

A pulsar "pulses" because

it magnetic axis crosses our line of sight.

When the Sun runs out of hydrogen in its core, it will become larger and more luminous because

it starts fusing hydrogen in a shell around a helium core.

If a star follows a horizontal path across the H-R diagram, the star

maintains the same luminosity.

According to Einstein's general theory of relativity, gravity is the

result of the distortion in spacetime around a massive object.

The International Space Station flies overhead. Using a telescope, you take a picture and measure its length to be ____ than its length as it would be measured if it were sitting on the ground.

slightly less

An astronaut who fell into a black hole would be stretched because:

the gravity changes so dramatically over a short distance.

Post-main-sequence stars lose up to 50 percent of their mass because

the star swells until the surface gravity is too weak to hold material.

Match the spectral type of a star to its approximate main-sequence lifetime.

A: 2 X 10^9 years G: 1 X 10^10 years M: 5 X 10^11 years O: 4 X 10^5 years

What may happen to a neutron star near this 3 solar mass limit that is in a close binary and is accreting (i.e., stealing) mass from its companion, as in the situation pictured here?

When the neutron star grows to 3 solar masses, it will collapse.

The following image shows the lifetime of a low-mass star on the H-R diagram. Place each label in the correct position on the image.

Where they are: -B is on the 0.01 R dotted line -C is right above the 1 R dotted line -E is on the 100 R dotted line -D is right below the 10 R dotted line -A is right below the 1 R dotted line What they are: -A. Main-sequence star -B. White dwarf -C. Planetary nebular ejection -D. Horizontal branch star -E. Helium flash

The figure shows a two-dimensional representation of a black hole in space. Identify where each items is located in the figure.

Where they are: -C is at the top -B is in the middle -A is at the bottom What they are: -A. Singularity -B. Event horizon -C. Normal space

The following figure displays the evolutionary track of a 1-Msun star. Place each description of the evolutionary stage in its correct location.

Where they are: -C is on the 0.01 Rsun dotted line -D is on the Main Sequence -B is just above the 100 Rsun dotted line -E and A are next to each other on the 10 Rsun dotted line, E is to the left of A What they are: -A. A hydrogen-burning shell surrounds a degenerate helium core. -B. Both a hydrogen-burning shell and a helium-burning shell surround a degenerate carbon core. -C. A degenerate carbon core radiates energy directly into space. -D. Outer layers of stellar atmosphere are ejected into space. -E. A hydrogen shell surrounds a helium-burning core.

When a star like the Sun moves up the red giant branch in the H-R diagram, it begins to burn hydrogen to helium in a shell surrounding a degenerate helium core. This cycle speeds up over time. In the following figure, label the descriptions of the missing steps in the cycle.

Where they are: -C is on the left side of the cycle -A is on the bottom of the cycle -B is on the right side of the cycle What they are: -A. ...a higher rate of nuclear fusion, which leads to... -B. ...a greater influx of material toward the core, which leads to... -C. ...an increase of inert mass within the core, which leads to...

The path of evolution of a Sun-like star is shown on this H-R diagram. Match the pictures of the star/s changing interior to the proper places on this evolutionary track.

Where they are: -D is next to the label "cooling white dwarfs" -A is at the very top of the diagram -C is on the corner point on the right side of the diagram -E is right above the Main Sequence, to the left of B What they look like: -A is a planetary nebula explosion -B is a red giant branch star -C is an asymptotic giant branch star -D is a white dwarf -E is a horizontal branch star

The interior of an evolved high-mass star has layers like an onion because

heavier atoms fuse closer to the center, where the temperature and pressure are higher.

Imagine you are on a spaceship. A second spaceship rockets past yours at 0.5 c. You start a stopwatch and stop it 10 seconds later. For an astronaut in the other spaceship, the number of seconds that have ticked by during the 10 seconds on your watch is

less than 10 seconds.