a set of steps by which four hydrogen nuclei fuse into one helium nucleus
0%
Most stars in the cluster are yellow or reddish in color.
0%
what most stars become when they die
0%
radius and surface temperature.
Q.2.
Two stars have the same spectral type. Star X is in luminosity class III, while Star Y is in luminosity class V.Star X must be larger in radius than Star Y.
0%
M stars
0%
visual binary
0%
True
0%
False
Q.3.
Light escaping from white dwarfs will show a gravitational redshift.
0%
False
0%
M stars
0%
True
0%
iron
Q.4.
Stars with high masses live longer than stars with lower masses.
0%
0.01 solar
0%
False
0%
O and B stars
0%
True
Q.5.
Observations show that elements with atomic mass numbers divisible by 4 (such as oxygen-16, neon-20, andmagnesium-24) tend to be more abundant in the universe than elements with atomic mass numbers inbetween. Why do we think this is the case?
0%
Near the end of a high-mass star's life, it produces new elements through a series of helium capturereactions.
0%
The diagram shows main-sequence stars of every spectral type except O, along with a few giants andsupergiants.
0%
At these high temperatures, nearly all the hydrogen is ionized, and is therefore unable to interact withlight.
0%
A few massive stars will form, live, and die before the majority of the star's clusters even complete theirprotostar stage.
Q.6.
What can we learn about a star from its life track on an H-R diagram?
0%
They generate energy through hydrogen fusion in their core.
0%
Higher core temperatures cause fusion to proceed much more rapidly.
0%
what surface temperature and luminosity it will have at each stage of its life
0%
It is the center of the black hole, a place of infinite density where the known laws of physics cannotdescribe the conditions.
Q.7.
The sketch above shows groups of stars on the H-R diagram, labeled (a) through (e); note that (a) representsthe entire main sequence while (c) and (d) represent only small parts of the main sequence. Which grouprepresents the most common type of stars?
0%
The diagram shows main-sequence stars of every spectral type except O, along with a few giants andsupergiants.
0%
d
0%
The entire mass of the Earth would end up as a thin layer, about 1 cm thick, over the surface of theneutron star.
0%
d .
Q.8.
What is the approximate surface temperature of a B star?
0%
Three quarters hydrogen, one quarter helium, no more than 2% heavier elements
0%
20,000 K
0%
0.01 solar
0%
They generate energy through hydrogen fusion in their core.
Q.9.
Based on current evidence, which of the following statements about gamma-ray bursts is true?
0%
stars that are more massive than eight times the mass of the Sun
0%
All of the above are true.
0%
All the bursts that we have detected occurred in distant galaxies.
0%
3 solar masses
Q.10.
A star of spectral type G will last approximately how long on the main sequence?
0%
10 million years
0%
10 million K
0%
10 billion years
0%
a 1 solar mass star
Q.11.
In any star cluster, stars with lower masses greatly outnumber those with higher masses.
0%
False
0%
iron
0%
True
0%
upper right
Q.12.
Why does a star grow larger immediately after it exhausts its core hydrogen?
0%
At these high temperatures, nearly all the hydrogen is ionized, and is therefore unable to interact withlight.
0%
when the rate of hydrogen fusion in the star's core is high enough to sustain gravitational equilibrium
0%
Hydrogen fusion in a shell outside the core generates enough thermal pressure to push the upperlayers outward.
0%
The diagram shows main-sequence stars of every spectral type except O, along with a few giants andsupergiants.
Q.13.
What is the approximate luminosity of a main-sequence M star?
0%
a 1 solar mass star
0%
O and B stars
0%
0.01 solar
0%
0.1 solar radius
Q.14.
What is a planetary nebula?
0%
gas ejected from a star in the final stage of its life
0%
a white dwarf star with a red giant binary companion
0%
They generate energy through hydrogen fusion in their core.
0%
a type of hydrogen fusion that uses carbon, nitrogen, and oxygen atoms as catalysts
Q.15.
What kind of star is most likely to become a white-dwarf supernova?
0%
below and to the right of the lowest part of the main sequence
0%
what surface temperature and luminosity it will have at each stage of its life
0%
They generate energy through hydrogen fusion in their core.
0%
a white dwarf star with a red giant binary companion
Q.16.
What do we mean by the main-sequence turnoff point of a star cluster, and what does it tell us?
0%
The diagram shows main-sequence stars of every spectral type except O, along with a few giants andsupergiants.
0%
when the rate of hydrogen fusion in the star's core is high enough to sustain gravitational equilibrium
0%
It is the spectral type of the hottest main-sequence star in a star cluster, and it tells us the cluster's age
0%
both stars have the same luminosity, but the apparent brightness of Star B is four times that of Star A
Q.17.
Which stellar spectral type has strong molecular absorption lines in its optical spectrum?
0%
d
0%
Higher core temperatures cause fusion to proceed much more rapidly.
0%
All of the above are true.
0%
B
Q.18.
Careful measurements reveal that a star maintains a steady apparent brightness at most times, except that atprecise intervals of 73 hours the star becomes dimmer for about 2 hours. The change in brightness alternatesbetween a small change and a large change. The most likely explanation is that ________.
0%
Three quarters hydrogen, one quarter helium, no more than 2% heavier elements
0%
the rate at which it converts hydrogen to helium.
0%
the star is a member of an eclipsing binary star system
0%
The diagram shows main-sequence stars of spectral types G, K, and M, along with numerous giantsand white dwarfs.
Q.19.
Which statement about accretion disks is not true?
0%
Degeneracy pressure varies with the temperature of the star.
0%
The core quickly heats up and expands as helium fusion begins all at once throughout the core.
0%
when the rate of hydrogen fusion in the star's core is high enough to sustain gravitational equilibrium
0%
The primary factor determining whether a white dwarf has an accretion disk is the white dwarf's mass.
Q.20.
What happens after the helium flash in the core of a star?
0%
The core quickly heats up and expands as helium fusion begins all at once throughout the core.
0%
when the rate of hydrogen fusion in the star's core is high enough to sustain gravitational equilibrium
0%
Hydrogen fusion in a shell outside the core generates enough thermal pressure to push the upperlayers outward.
0%
what surface temperature and luminosity it will have at each stage of its life
Q.21.
Which of the following statements about degeneracy pressure is not true?
0%
Degeneracy pressure varies with the temperature of the star.
0%
luminosity
0%
H-R diagrams of globular clusters
0%
Brown dwarfs eventually collapse to become white dwarfs.
Q.22.
If you were to come back to our solar system in 6 billion years, what might you expect to find?
0%
a white dwarf
0%
O and B stars
0%
10 billion years
0%
as much as a large vehicle
Q.23.
On the main sequence, stars obtain their energy
0%
a 1 solar mass star
0%
.More massive stars live much shorter lives than less massive stars.
0%
by converting hydrogen to helium.
0%
can be determined for main-sequence stars but not for other types of stars
Q.24.
Two stars both lie on the main sequence. Star X is spectral type A, while Star Y is spectral type G. Star X mustbe more massive than Star Y.
0%
False
0%
True
0%
iron
0%
their radii
Q.25.
The total amount of power (in watts, for example) that a star radiates into space is called its ________.
0%
their radii
0%
lower right
0%
luminosity
0%
lower left
Q.26.
What types of stars end their lives with supernovae?
0%
Most stars in the cluster are yellow or reddish in color.
0%
when the rate of hydrogen fusion in the star's core is high enough to sustain gravitational equilibrium
0%
what surface temperature and luminosity it will have at each stage of its life
0%
stars that are more massive than eight times the mass of the Sun
Q.27.
Which of the following best describes what would happen if a 1.5 solar mass neutron star, with a diameter ofa few kilometers, were suddenly to appear in your hometown?
0%
The entire mass of the Earth would end up as a thin layer, about 1 cm thick, over the surface of theneutron star.
0%
The primary factor determining whether a white dwarf has an accretion disk is the white dwarf's mass.
0%
Temperatures skyrocket to the point where carbon fusion is possible, which leads to a white dwarfsupernova explosion.
0%
apparent brightness = luminosity/ 4pi x (distance)^2
Q.28.
On a Hertzsprung-Russell diagram, where would you find stars that are cool and have low luminosities?
0%
lower right
0%
10 million K
0%
lower left
0%
a 1 solar mass star
Q.29.
You observe a red giant star. What is happening to that star?
0%
Hydrogen fusion in a shell outside the core generates enough thermal pressure to push the upperlayers outward.
0%
Three quarters hydrogen, one quarter helium, no more than 2% heavier elements
0%
It is increasing in size, and is fusing hydrogen in a shell around its core.
0%
They generate energy through hydrogen fusion in their core.
Q.30.
Which star spends the longest time in the protostellar phase of life?
0%
luminosity
0%
as much as a large vehicle
0%
10 million years
0%
a 1 solar mass star
Q.31.
Will our Sun ever undergo a white dwarf supernova explosion? Why or why not?
0%
No, because it is not orbited by another star.
0%
It is significantly less massive than the Sun.
0%
It would evolve more quickly than it is now.
0%
a 1 solar mass star
Q.32.
How is the lifetime of a star related to its mass?
0%
.More massive stars live much shorter lives than less massive stars.
0%
Degeneracy pressure varies with the temperature of the star.
0%
an explosion on the surface of a white dwarf in a close binary system
0%
a type of hydrogen fusion that uses carbon, nitrogen, and oxygen atoms as catalysts
Q.33.
Which of the following statements about brown dwarfs is not true?
0%
Brown dwarfs eventually collapse to become white dwarfs.
0%
Degeneracy pressure varies with the temperature of the star.
0%
apparent brightness = luminosity/ 4pi x (distance)^2
0%
All of the above are true.
Q.34.
Consider the star to which the arrow points. Which of the following statements about this star is not true?
0%
It is increasing in size, and is fusing hydrogen in a shell around its core.
0%
A few massive stars will form, live, and die before the majority of the star's clusters even complete theirprotostar stage.
0%
apparent brightness = luminosity/ 4pi x (distance)^2
0%
It is significantly less massive than the Sun.
Q.35.
Which of the following terms is given to a pair of stars that appear to change position in the sky, indicatingthat they are orbiting one another?
0%
O and B stars
0%
apparent brightness = luminosity/ 4pi x (distance)^2
0%
H-R diagrams of globular clusters
0%
visual binary
Q.36.
it is a graph with a blocked question:-)
0%
A) About 1 solar
0%
gas ejected from a star in the final stage of its life
0%
O and B stars
0%
as much as a large vehicle
Q.37.
The helium fusion process works by fusing two helium nuclei into one beryllium nucleus.
0%
True
0%
M stars
0%
False
0%
iron
Q.38.
Suppose you were unfortunate enough to fall into a black hole in a binary system where the black hole wasaccreting matter from its companion star. Which of the following is most likely to kill you first?
0%
apparent brightness = luminosity/ 4pi x (distance)^2
0%
X-rays from the accretion disk
0%
H-R diagrams of globular clusters
0%
by converting hydrogen to helium.
Q.39.
Based on current understanding, the minimum mass of a black hole that forms during a massive starsupernova is roughly ________.
0%
3 solar masses
0%
luminosity
0%
lower right
0%
0.1 solar radius
Q.40.
Which of the statements below about black holes is not true?
0%
O and B stars
0%
A spaceship passing a few million kilometers from a 10 solar mass black hole is much more likely to bedestroyed than a spaceship passing at the same distance from the center of a 10 solar massmain-sequence star
0%
It is the center of the black hole, a place of infinite density where the known laws of physics cannotdescribe the conditions.
0%
Degeneracy pressure varies with the temperature of the star.
Q.41.
Consider a large molecular cloud that will give birth to a cluster of stars. Which of the following would youexpect to be true?
0%
The diagram shows main-sequence stars of every spectral type except O, along with a few giants andsupergiants.
0%
.More massive stars live much shorter lives than less massive stars.
0%
A few massive stars will form, live, and die before the majority of the star's clusters even complete theirprotostar stage.
0%
Temperatures skyrocket to the point where carbon fusion is possible, which leads to a white dwarfsupernova explosion.
Q.42.
When does a star become a main-sequence star?
0%
can be determined for main-sequence stars but not for other types of stars
0%
At these high temperatures, nearly all the hydrogen is ionized, and is therefore unable to interact withlight.
0%
when the rate of hydrogen fusion in the star's core is high enough to sustain gravitational equilibrium
0%
Higher core temperatures cause fusion to proceed much more rapidly.
Q.43.
The choices below each describe the appearance of an H-R diagram for a different star cluster. Which clusteris most likely to be located in the halo of our galaxy?
0%
It is the spectral type of the hottest main-sequence star in a star cluster, and it tells us the cluster's age
0%
The diagram shows main-sequence stars of spectral types G, K, and M, along with numerous giantsand white dwarfs.
0%
The entire mass of the Earth would end up as a thin layer, about 1 cm thick, over the surface of theneutron star.
0%
H-R diagrams of globular clusters
Q.44.
Photographs of many young stars show long jets of material apparently being ejected from their poles.
0%
Three quarters hydrogen, one quarter helium, no more than 2% heavier elements
0%
True
0%
False
0%
M stars
Q.45.
Which of the following statements about apparent and absolute magnitudes is true?
0%
apparent brightness = luminosity/ 4pi x (distance)^2
0%
Brown dwarfs eventually collapse to become white dwarfs.
0%
All of the above are true.
0%
Most stars in the cluster are yellow or reddish in color.
Q.46.
Which of the following types of stars is the most common?
0%
M stars
0%
All of the above are true.
0%
0.01 solar
0%
20,000 K
Q.47.
Our Sun will end its life in a planetary nebula and become a white dwarf.
0%
False
0%
True
0%
upper right
0%
M stars
Q.48.
A star of spectral type B with a mass of 10 times the mass of the Sun will last approximately how long on themain sequence?
0%
a white dwarf
0%
3 solar masses
0%
10 million years
0%
10 million K
Q.49.
The maximum mass for a white dwarf is 1.4 solar masses.
0%
0.01 solar
0%
False
0%
iron
0%
True
Q.50.
How are elements beyond iron formed in massive-star supernovae?
0%
below and to the right of the lowest part of the main sequence
0%
Neutrons produced during the core collapse are slammed into atomic nuclei.
0%
Brown dwarfs eventually collapse to become white dwarfs.
0%
what surface temperature and luminosity it will have at each stage of its life
Q.51.
What do we mean by the singularity of a black hole?
0%
It is the center of the black hole, a place of infinite density where the known laws of physics cannotdescribe the conditions.
0%
when the rate of hydrogen fusion in the star's core is high enough to sustain gravitational equilibrium
0%
below and to the right of the lowest part of the main sequence
0%
Hydrogen fusion in a shell outside the core generates enough thermal pressure to push the upperlayers outward.
Q.52.
On an H-R diagram, stellar masses ________.
0%
.More massive stars live much shorter lives than less massive stars.
0%
what surface temperature and luminosity it will have at each stage of its life
0%
when the rate of hydrogen fusion in the star's core is high enough to sustain gravitational equilibrium
0%
can be determined for main-sequence stars but not for other types of stars
Q.53.
Our Sun will likely undergo a nova event in about 5 billion years.
0%
False
0%
True
0%
a white dwarf
0%
O and B stars
Q.54.
When we see X-rays from an accretion disk in a binary system, we can't immediately tell whether theaccretion disk surrounds a neutron star or a black hole. Suppose we then observe each of the followingphenomena in this system. Which one would rule out the possibility of a black hole?
0%
All of the above are true.
0%
a white dwarf
0%
intense X-ray bursts
0%
H-R diagrams of globular clusters
Q.55.
What is the approximate chemical composition (by mass) with which all stars are born?
0%
They generate energy through hydrogen fusion in their core.
0%
It is increasing in size, and is fusing hydrogen in a shell around its core.
0%
Most stars in the cluster are yellow or reddish in color.
0%
Three quarters hydrogen, one quarter helium, no more than 2% heavier elements
Q.56.
Why do O stars exhibit weak hydrogen absorption lines?
0%
At these high temperatures, nearly all the hydrogen is ionized, and is therefore unable to interact withlight.
0%
Most stars in the cluster are yellow or reddish in color.
0%
It is the center of the black hole, a place of infinite density where the known laws of physics cannotdescribe the conditions.
0%
A spaceship passing a few million kilometers from a 10 solar mass black hole is much more likely to bedestroyed than a spaceship passing at the same distance from the center of a 10 solar massmain-sequence star
Q.57.
This diagram represents the life track of a 1 solar mass star. Refer to the life stages labeled with romannumerals. Which stage lasts the longest?
0%
iii
0%
True
0%
luminosity
0%
their radii
Q.58.
What is the common trait of all main-sequence stars?
0%
stars that are more massive than eight times the mass of the Sun
0%
Degeneracy pressure varies with the temperature of the star.
0%
They generate energy through hydrogen fusion in their core.
0%
.More massive stars live much shorter lives than less massive stars.
Q.59.
Which of the following stellar properties has the greatest range in values?
0%
All of the above are true.
0%
H-R diagrams of globular clusters
0%
Most stars in the cluster are yellow or reddish in color.
0%
luminosity
Q.60.
A star's luminosity depends primarily on its
0%
All of the above are true.
0%
H-R diagrams of globular clusters
0%
radius and surface temperature.
0%
0.1 solar radius
Q.61.
All massive-star supernovae leave behind black holes as remnants.
0%
True
0%
It is increasing in size, and is fusing hydrogen in a shell around its core.
0%
False
0%
M stars
Q.62.
On a Hertzsprung-Russell diagram, where would you find white dwarfs?
0%
10 billion years
0%
False
0%
lower left
0%
True
Q.63.
A 10 solar mass star is about ten times more luminous than a 1 solar mass star.
0%
False
0%
0.01 solar
0%
luminosity
0%
True
Q.64.
After a massive-star supernova, what is left behind?
0%
Higher core temperatures cause fusion to proceed much more rapidly.
0%
what most stars become when they die
0%
either a neutron star or a black hole
0%
the rate at which it converts hydrogen to helium.
Q.65.
Which element has the lowest mass per nuclear particle and therefore cannot release energy by either fusionor fission?
0%
True
0%
False
0%
iron
0%
luminosity
Q.66.
If you had something the size of a sugar cube that was made of white dwarf matter, on Earth it would weigh________.
0%
a white dwarf
0%
as much as a large vehicle
0%
All of the above are true.
0%
It would evolve more quickly than it is now.
Q.67.
The sketch above shows groups of stars on the H-R diagram, labeled (a) through (e); note that (a) representsthe entire main sequence while (c) and (d) represent only small parts of the main sequence. Which grouprepresents stars that have no ongoing nuclear fusion?
0%
A
0%
d .
0%
intense X-ray bursts
0%
b
Q.68.
We can measure the parallax of most stars in our galaxy.
0%
lower left
0%
True
0%
stars that are more massive than eight times the mass of the Sun
0%
False
Q.69.
The more distant a star, the smaller its parallax.
0%
M stars
0%
True
0%
False
0%
when the rate of hydrogen fusion in the star's core is high enough to sustain gravitational equilibrium
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