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Astronomy test 2

Which of these colors of light passes most easily through interstellar clouds?
yellow light
A protostar is a __________.
star that is still in the process of forming
Recall that a main-sequence star is what we usually think of as a "normal" star, meaning one that generates energy through hydrogen fusion in its core. On the H-R diagram shown in this activity, main-sequence stars can be found __________.
along the well-defined curve running from the upper left to the lower right
The position of a star along the main sequence is determined by the star's __________.
The position of a star (or protostar) on the H-R diagram tell us its __________.
surface temperature and luminosity
A group of stars with the same luminosity would form a _____ line on the H-R diagram.
Suppose one star is directly above another on the H-R diagram. What can you conclude about the two stars?
Both stars have the same surface temperature, but the one higher up is more luminous.
Suppose two protostars form at the same time, one with a mass of 0.5 and the other with a mass of 15. Which of the following statements are true?
The 15 protostar will be much more luminous than the 0.5 protostar.
The 15 star will end its main-sequence life before the 0.5 star even completes its protostar stage.
Star clusters are extremely useful to astronomers for two key reasons:
All the stars in a cluster lie at about the same distance from Earth.
All the stars in the cluster formed from the same interstellar cloud and therefore began to form at about the same time.
Astronomers can therefore use star clusters as laboratories for comparing the properties of stars at about the same distance or of about the same age.
By observing and comparing protostars and stars of different masses within a single star cluster.
A molecular cloud fragment is __________.
a piece of a larger star-forming cloud in which one or a few stars will form.
In general, a contracting cloud will heat up only if __________.
it is dense enough to trap light inside it.
A contracting cloud loses gravitational potential energy as it contracts in size. What happens to this energy?
It is converted to light and to heat within the cloud.
Angular momentum must be conserved as a cloud contracts. Therefore, in a contracting cloud, __________.
the rotation rate must increase as it shrinks in size.
From the H-R diagram we can directly read off __________.
an object's surface temperature and luminosity
As a clump of interstellar gas contracts to become a main-sequence star, its changing position on the H-R diagram tells us __________.
how its outward appearance is changing
On the H-R diagram, hotter objects are plotted __________ than cooler objects.
farther to the left
On the H-R diagram, more luminous objects are plotted __________ on the graph than less luminous objects.
higher up
Watch the red dot representing the protostar in the animation. After it reaches its highest point on the diagram, how do the protostar's surface temperature and luminosity change as it approaches the main sequence?
Its surface temperature increases, but its luminosity decreases.
When does a newly forming star have the greatest luminosity?
when it is a shrinking protostar with no internal fusion
In the interactive figure, the red dot represents an object at its maximum luminosity when the dot appears __________.
at its highest point on the H-R diagram
When a newly forming star is at its greatest luminosity, what is its energy source?
gravitational contraction
Protostars shine with energy generated by _____.
gravitational contraction
What happens within a contracting cloud in which gravity is stronger than pressure and temperature remains constant?
It breaks into smaller fragments.
Why are the very first stars thought to have been much more massive than the Sun?
The temperatures of the clouds that made them were higher because they consisted entirely of hydrogen and helium.
What slows down the contraction of a star-forming cloud when it makes a protostar?
trapping of thermal energy inside the protostar
For main-sequence stars, which of the following lists the spectral types in order of decreasing mass?
Radiation pressure is produced by __________.
Among stars within about 50 light-years of our solar system, __________.
very low-mass stars are the most common, and higher-mass stars are increasingly rare
Definition of a molecular cloud
a cool, dense interstellar cloud in which the low temperatures allow hydrogen atoms to pair up into hydrogen molecules.
Definition of thermal pressure
is the ordinary pressure in a gas, arising from motions of particles, that can be attributed to the object's temperature.
Definition of a protostellar disk
is a disk of material surrounding a forming star that has not yet reached the point where sustained fusion can occur in its core; it is essentially the same as a proto-planetary disk, but may not necessarily lead to planet formation
Definition of a protostellar wind
is the relatively strong wind from a forming star that has not yet reached the point where sustained fusion can occur in its core.
Definition of a jet
is a high-speed stream of gas ejected from an object into space.
Definition of a close binary
is a binary star system in which the two stars are very close together.
Definition of degeneracy pressure
is a type of pressure unrelated to an object's temperature, which arises when electrons (electron degeneracy pressure) or neutrons (neutron degeneracy pressure) are packed so tightly that the exclusion and uncertainty principles come into play.
Definition of a brown dwarf
is an object too small to become an ordinary star because electron degeneracy pressure halts its gravitational collapse before fusion becomes self-sustaining; brown dwarfs have mass less than 0.08
Which two processes can generate energy to help a star or gas cloud maintain its internal thermal pressure?
nuclear fusion and gravitational contraction
About what percentage of the mass of a molecular cloud is in the form of dust?
How do we learn the chemical composition of the interstellar medium?
By studying spectra of interstellar gas clouds.
What happens to the visible light radiated by stars located within a dusty gas cloud?
It is absorbed by dust, which heats the dust grains so that they emit the absorbed energy as infrared light.
Under which circumstances can you be sure that the thermal pressure within a gas cloud is increasing?
the cloud's temperature and density are both increasing
Which process is required to allow a gravitationally-collapsing gas cloud to continue to collapse?
The cloud must radiate away much of its thermal energy.
According to current understanding, how did the first generation of stars differ from stars born today?
They were much more massive than most stars born today.
Angular momentum plays an important role in star formation. Which of the following characteristics of a protostellar system is probably not strongly affected by the star's angular momentum?
the onset of core hydrogen fusion
Close binary star systems are thought to form when _____.
gravity pulls two neighboring protostars quite close together, but angular momentum causes them to orbit each other rather than colliding.
Generally speaking, how does the surface temperature and luminosity of a protostar compare to the surface temperature and luminosity of the main-sequence star it becomes?
A main-sequence star is hotter and dimmer than it was as a protostar.
Where does a 1-solar-mass protostar appear on an H-R diagram?
to the right of the main sequence, and higher up than the Sun
Why does the rotation of a protostar slow down over time?
Magnetic fields can transfer angular momentum to the protostellar disk and protostellar winds can carry angular momentum away
The surface of a protostar radiates energy while its core ________.
shrinks and heats
The core of a protostar that will eventually become a brown dwarf shrinks until ______.
the type of pressure called degeneracy pressure becomes important
If a star is extremely massive (well over 100 solar masses), why isn't it likely to survive for long?
It may blow itself apart because of radiation pressure.
Consider a large molecular cloud that will give birth to a cluster of stars. Which of the following would you expect to be true?
A few massive stars will form, live, and die before the majority of the star's clusters even complete their protostar stage
We do not know for certain whether the general trends we observe in stellar birth masses also apply to brown dwarfs. But if they do, then which of the following would be true?
Brown dwarfs would outnumber all ordinary stars.
Where would a brown dwarf be located on an H-R diagram?
below and to the right of the lowest part of the main sequence
What do we mean by the interstellar medium?
the gas and dust that lies in between the stars in the Milky Way galaxy
The interstellar clouds called molecular clouds are _______.
the cool clouds in which stars form
Which of the following types of molecule is the most abundant in an interstellar molecular cloud?
Interstellar dust consists mostly of _____.
microscopic particles of carbon and silicon
Which part of the electromagnetic spectrum generally gives us our best views of stars forming in dusty clouds?
Suppose you look by eye at a star near the edge of a dusty interstellar cloud. The star will look _______ than it would if it were outside the cloud.
dimmer and redder
Most interstellar clouds remain stable in size because the force of gravity is opposed by _______ within the cloud.
thermal pressure
What kind of gas cloud is most likely to give birth to stars?
a cold, dense gas cloud
What effect are magnetic fields thought to have on star formation in molecular clouds?
They can help resist gravity, so that more total mass is needed before the cloud can collapse to form stars.
Which of the following statements is probably true about the very first stars in the universe?
They were made only from hydrogen and helium.
What is a protostar?
a star that is still in the process of forming
Which of the following phenomena is not commonly associated with the star formation process?
intense ultraviolet radiation coming from a protostar
What law explains why a collapsing cloud usually forms a protostellar disk around a protostar?
conservation of angular momentum
What can we learn about a star from a life track on an H-R diagram?
the surface temperature and luminosity the star will have at each stage of its life
When does a protostar become a main-sequence star?
when the rate of hydrogen fusion becomes high enough to balance the rate at which the star radiates energy into space
Approximately what core temperature is required before hydrogen fusion can begin in a star?
10 million K
Which star spends the longest time in the protostellar phase of life?
a 1 solar mass star
What is the approximate range of masses that newborn main sequence stars can have?
0.1 to 150 solar masses
The vast majority of stars in a newly formed star cluster are ______.
less massive than the Sun
Which of the following statements about brown dwarfs is not true?
Brown dwarfs eventually collapse to become white dwarfs.
The Sun's photosphere is __________.
the visible surface of the Sun
The word corona, as in the Sun's corona, means _____.
As you go upward in altitude through Earth's atmosphere __________.
the density steadily decreases
How do we observe different layers of the Sun's atmosphere?
We use visible-light telescopes to observe the photosphere, ultraviolet telescopes to observe the chromosphere, and X-ray telescopes to observe the corona.
When we observe the Sun with an X-ray telescope, we see the _____.
The layer of the Sun's atmosphere that is best observed with an ultraviolet telescope is the _____.
The Sun's photosphere is __________.
the visible surface of the Sun.
Fusion requires bringing two positively charged nuclei so close together that the strong nuclear force can hold them against the electromagnetic repulsion of their positive charges. What conditions make fusion possible?
extremely high temperature and high density
When the Sun's core contracts, the core temperature _____.
What equilibrium for the core of a star means
The core of a star is in equilibrium when its temperature, size, and the rate of nuclear fusion all hold steady.
Suppose you could somehow start nuclear fusion in a box that stayed the same size. Increasing the fusion rate would cause the temperature inside the box to _____.
If you heat up a balloon, what happens to it?
The gas particles inside it move faster, causing it to expand until it stabilizes at a new, larger size.
If you heat up a balloon, what happens to it?
The gas particles inside it move faster, causing it to expand until it stabilizes at a new, larger size.
What would happen if the fusion rate in the core of the Sun were increased but the core could not expand?
The Sun's core would start to heat up and the rate of fusion would increase even more
Our current understanding of nuclear fusion in the Sun's core is based primarily on __________.
applying the laws of physics to calculate what must be occurring inside the Sun
Which of the following lists the Sun's layers in the correct order (staring from the Sun's center and going outward)?
core, radiation zone, convection zone, photosphere, chromosphere, corona
Which of the following statements accurately describes how we can best study different layers of the Sun with telescopes either on the ground or in space?
We observe the photosphere with visible-light telescopes, the chromosphere with ultraviolet-light telescopes, and the corona with X-ray telescopes.
Definition of a neutrino
a lightweight (almost massless) particle that is a by-product of nuclear reactions and radioactive decay.
Which of the following lists the Sun's layers in the correct order (staring from the Sun's center and going outward)?
core, radiation zone, convection zone, photosphere, chromosphere, corona
Which of the following statements accurately describes how we can best study different layers of the Sun with telescopes either on the ground or in space?
We observe the photosphere with visible-light telescopes, the chromosphere with ultraviolet-light telescopes, and the corona with X-ray telescopes
Listed following are the different layers of the Sun. Rank these layers based on their distance from the Sun's center, from greatest to least.
Corona, Chromosphere, Photosphere, Convection Zone, Radiation Zone, Core
Rank the layers of the Sun based on their density, from highest to lowest.
Core, Radiation Zone, Convection Zone, Photosphere, Chromosphere, Corona
Rank the following layers of the Sun based on their temperature, from highest to lowest.
Core, Radiation Zone, Convection Zone, Photosphere
Rank the following layers of the Sun based on the pressure within them, from highest to lowest.
Core, Radiation Zone, Convection Zone, Photosphere
In which of the following layer(s) of the Sun does nuclear fusion occur?
The Sun is in gravitational equilibrium throughout its interior, which means that ___________.
the inward pull of gravity is everywhere balanced by the outward push of pressure inside the Sun
Which of the following layers of the Sun can be seen with some type of telescope?
Photosphere, Chromosphere, Corona
What a convection zone is
a region in which energy is transported outward by convection, which means hot material will rise and cooler material will fall
What a chromosphere is
the layer of the Sun's atmosphere below the corona; most of the Sun's ultraviolet light is emitted from this region, in which the temperature is about 10,000 K.
What a photosphere is
the visible surface of the Sun, where the temperature averages just under 6,000 K.
What a radiation zone is
a region of the interior of a star in which energy is transported primarily by radiative diffusion.
What a core is
the central region of a star, in which nuclear fusion can occur
What a corona is
the tenuous uppermost layer of the Sun's atmosphere; most of the Sun's X rays are emitted from this region, in which the temperature is about 1 million K.
the average time from one solar minimum to the next is approximately _____.
11 years
Why do sunspots appear darker than their surroundings?
They are cooler than their surroundings
What is the most common kind of element in the solar wind
According to modern science, approximately how old is the Sun?
4 1/2 billion years
The Sun will exhaust its nuclear fuel in about ______.
5 billion years
Which of the following correctly describes how the process of gravitational contraction can make a star hot?
When a star contracts in size, gravitational potential energy is converted to thermal energy
What two physical processes balance each other to create the condition known as gravitational equilibrium in stars?
gravitational force and outward pressure
The source of energy that keeps the Sun shining today is _________.
nuclear fusion
When we say that the Sun is a ball of plasma, we mean that _________.
the Sun consists of gas in which many or most of the atoms are ionized (missing electrons)
What is the Sun made of (by mass)?
70% hydrogen, 28% helium, 2% other elements
What are the appropriate units for the Sun's luminosity?
The Sun's surface, as we see it with our eyes, is called the _________.
What is the solar wind?
a stream of charged particles flowing outward from the surface of the Sun
The fundamental nuclear reaction occurring in the core of the Sun is _________.
nuclear fusion of hydrogen into helium
The proton-proton chain is _________.
the specific set of nuclear reactions through which the Sun fuses hydrogen into helium
The overall result of the proton-proton chain is:
4 H becomes 1 He + energy
To estimate the central temperature of the Sun, scientists _________.
use computer models to predict interior conditions
Why are neutrinos so difficult to detect?
They have a tendency to pass through just about any material without any interactions.
Which statement best describes what was called the solar neutrino problem?
Early experiments designed to detect solar neutrinos found them, but in fewer numbers than had been expected.
The light radiated from the Sun's surface reaches Earth in about 8 minutes, but the energy of that light was released by fusion in the solar core about _________.
a few hundred thousand years ago
What happens to energy in the Sun's convection zone?
Energy is transported outward by the rising of hot plasma and sinking of cooler plasma.
What do sunspots, solar prominences, and solar flares all have in common?
They are all strongly influenced by magnetic fields on the Sun.
Which of the following is not a characteristic of the 11-year sunspot cycle?
The sunspot cycle is very steady, so that each 11-year cycle is nearly identical to every other 11-year cycle.
How is the sunspot cycle directly relevant to us here on Earth?
Coronal mass ejections and other activity associated with the sunspot cycle can disrupt radio communications and knock out sensitive electronic equipment
How do the properties of long-lived stars compare to those of short-lived stars?
both mass and luminosity
True or False? More massive main-sequence stars are less luminous than less massive main-sequence stars.
How do the properties of long-lived stars compare to those of short-lived stars?
Long-lived stars begin their lives with less mass and a smaller amount of hydrogen fuel

Long-lived stars are less luminous during their main-sequence lives
A main-sequence star twice as massive as the Sun will be about
ten times as luminous
A main-sequence star twice as massive as the Sun would last __________.
much less than half as long as the Sun
The fusion rate in the core of a main-sequence star will be greater if the core temperature and density are higher.
How do the life stages of a high-mass star compare to those of a low-mass star?
Both low- and high-mass stars are protostars until they can fuse hydrogen in their cores, then become hydrogen-burning main-sequence stars, and near the ends of their lives expand to become giants or supergiants.
Protostar is the name we give to __________.
a star that has not quite reached its "birth," meaning its core is not yet hot enough to sustain nuclear fusion
What makes a supergiant shine?
nuclear fusion of elements heavier than hydrogen (as well as of hydrogen in the shell)
Which of the following lists the elements in order of increasing atomic mass?
helium, carbon, oxygen, iron
A main-sequence star is __________.
a star in the longest stage of its life, in which it is fusing hydrogen into helium in its core
Protostar is the name we give to __________.
a star that has not quite reached its "birth," meaning its core is not yet hot enough to sustain nuclear fusion
A red giant shines with energy released by __________.
hydrogen fusion in a shell surrounding an inert helium core
A white dwarf is __________.
the dead remains of a low-mass star
On the H-R diagram, red giants are found __________.
toward the upper right, where stars are bright but cool
On the H-R diagram, white dwarfs are found __________.
in the lower left, where stars are dim but hot
Description of a supernova
is the complete explosion of a star
Description of a neutron star
the compact corpse of a high-mass star left over after a supernova. It typically contains a mass comparable to the mass of the Sun in a volume just a few kilometers in radius.
Description of a supernova remnant
is a glowing, expanding cloud of debris from the explosion of a star
Description of a high-mass star
is a star born with a mass above about 8Msun which will end its life by exploding as a supernova
Description of the CNO cycle
the cycle of reactions by which intermediate- and high-mass stars fuse hydrogen into helium.
Description of a helium-capture reaction
is a fusion reaction that fuses a helium nucleus into some other nucleus. Such reactions can fuse carbon into oxygen, oxygen into neon, neon into magnesium, and so on.
Description of Supernova 1987A
was a supernova witnessed on Earth in 1987. It was the nearest supernova seen in nearly 400 years and helped astronomers refine their theories of supernovae
The diagram indicates that the third most abundant element in the Milky Way Galaxy is _____.
According to the diagram, the approximate abundance of oxygen atoms in the galaxy is __________.
1/1000 that of hydrogen
what is the most abundant element with an atomic number greater than or equal to 20?
which of the following statements best describes the observed pattern of abundances for elements with an atomic number between 6 and 20?
There is a general trend of decreasing abundance with increasing atomic number, but elements with even atomic numbers tend to be more abundant than those with odd atomic numbers.
According to current understanding, the two most abundant elements in the universe were made __________.
in the Big Bang
The element with two protons, or having an atomic number of 2, is _____.
Adding a neutron __________ the atomic number of a nucleus.
does not change
Our Sun is considered to be a ______.
low-mass star
Which of the following types of data provide evidence that helps us understand the life tracks of low-mass stars?
H-R diagrams of globular clusters
Why is a 1 solar-mass red giant more luminous than a 1 solar-mass main sequence star?
Fusion reactions are producing energy at a greater rate in the red giant
Which of the following describes a star with a hydrogen-burning shell and an inert helium core?
It is a red giant that grows in luminosity until it dies in a planetary nebula
Which of the following observations would not be likely to provide information about the final, explosive stages of a star's life?
decades of continuous monitoring of red giants in a globular cluster
Which is more common: a star blows up as a supernova, or a star forms a planetary nebula/white dwarf system?
Planetary nebula formation is more common
Carbon fusion occur in high-mass stars but not in low-mass stars because _________.
the cores of low-mass stars never get hot enough for carbon fusion
Which of the following statements about various stages of core nuclear burning (hydrogen, helium, carbon, etc.) in a high-mass star is not true?
Each successive stage lasts for approximately the same amount of time
Which event marks the beginning of a supernova?
The sudden collapse of an iron core into a compact ball of neutrons
Suppose that the star Betelgeuse (the upper left shoulder of Orion) were to supernova tomorrow (as seen here on Earth). What would it look like to the naked eye?
Betelgeuse would remain a dot of light, but would suddenly become so bright that, for a few weeks, we'd be able to see this dot in the daytime
Observations show that elements with atomic mass numbers divisible by 4 (such as oxygen-16, neon-20, and magnesium-24) tend to be more abundant in the universe than elements with atomic mass numbers in between. Why do we think this is the case?
At the end of a high-mass star's life, it produces new elements through a series of helium capture reactions
A spinning neutron star has been observed at the center of a ______.
supernova remnant
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?
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.
Tidal forces are very important to the Algol system today, but were not important when both stars were still on the main sequence. Why not?
Main sequence stars in a system like the Algol system are small compared to their physical separation.
Which of the following stars will live longest?
1 solar-mass star
In the context of understanding stellar lives, "high-mass" stars have masses:
more than about 8 times the mass of our Sun
Which of the following lists the stages of life for a low-mass star in the correct order?
protostar, main-sequence star, red giant, planetary nebula, white dwarf
What happens when a main-sequence star exhausts its core hydrogen fuel supply?
The core shrinks while the rest of the star expands.
The main source of energy for a star as it grows in size to become a red giant is ______.
hydrogen fusion in a shell surrounding the central core
The overall helium fusion reaction is:
Three helium nuclei fuse to form one carbon nucleus.
What is a helium flash?
The sudden onset of helium fusion in the core of a low-mass star.
What is a planetary nebula?
Gas ejected from a low-mass star in the final stage of its life.
The ultimate fate of our Sun is to _____.
become a white dwarf that will slowly cool with tim
Which low-mass star does not have fusion occurring in its central core?
a red giant
How are low-mass red giant stars important to our existence?
These stars manufactured most of the carbon atoms in our bodies.
Which of the following pairs of atomic nuclei would feel the strongest repulsive electromagnetic force if you tried to push them together?
helium and helium
Which of the following stars will certainly end its life in a supernova?
a 10 solar mass star
What is the CNO cycle?
a set of steps by which four hydrogen nuclei fuse into one helium nucleus
In order to predict whether a star will eventually fuse oxygen into a heavier element, what do you need to know about the star?
its mass
Why is iron significant to understanding how a supernova occurs?
Iron cannot release energy either by fission or fusion.
After a supernova explosion, the remains of the stellar core ______.
may be either a neutron star or a black hole
Why is Supernova 1987A particularly important to astronomers?
It is the nearest supernova to have occurred at a time when we were capable of studying it carefully with telescopes
Algol consist of a 3.7 MSun main-sequence star and a 0.8 MSun subgiant. Why does this seem surprising, at least at first?
The two stars should be the same age, so we'd expect the subgiant to be more massive than the main-sequence star
Where does gold (the element) come from?
it is produced during the supernova explosions of high-mass stars
A white dwarf explodes as a supernova when its mass exceeds the white-dwarf limit of 1.4 solar masses. How does this happen?
Mass transfer from or merger with a companion star can raise a white dwarf's mass above the limit.
White dwarfs are made mostly of __________.
carbon and oxygen
In general, we can detect a black hole left behind by a dead star __________.
only if mass is being transferred to it by another star
Description of a white dwarf
is the hot, compact corpse of a low-mass star, typically with a mass similar to the Sun compressed to a volume the size of the Earth.
Description of a black hole
an object in which gravity has overcome all sources of pressure support, causing it to collapse without end. Its event horizon is the place from within which no information can leave the black hole. The Schwarzschild radius of the black hole essentially defines the "size" of the event horizon.
The definition of electron degeneracy pressure
a type of pressure that arises when electrons are packed as tightly as the laws of quantum physics allow. Unlike ordinary (thermal) pressure, the strength of electron degeneracy pressure does not depend on an object's temperature.
The definition of the white dwarf limit
its maximum possible mass, which is about 1.4 . It is sometimes called the Chandrasekhar limit, after the man who first calculated it. For an object with mass above this limit, gravity is too strong to be resisted by electron degeneracy pressure.
The definition of an accretion disk
is a rapidly rotating disk of material, which gradually falls inward as it orbits a star-like object (e.g., white dwarf, neutron star, or black hole).
The definition of a nova
is the dramatic brightening of a star, which lasts for a few weeks and then subsides. It occurs when a burst of hydrogen fusion ignites in a shell on the surface of an accreting white dwarf in a binary star system.
The definition of a white dwarf supernova
occurs when an accreting white dwarf reaches the white dwarf limit, ignites runaway carbon fusion, and explodes like a bomb.
The definition of a massive star supernova
occurs when a massive star dies, initiated by the catastrophic collapse of its iron core
Which of these isolated neutron stars must have had a binary companion?
an isolated pulsar that pulses 600 times per second
What would happen to a neutron star with an accretion disk orbiting in a direction opposite to the neutron star's spin?
Its spin would slow down.
Which of these objects has the smallest radius?
a 1.2Msun white dwarf
According to our modern understanding, what is a nova?
an explosion on the surface of a white dwarf in a close binary system
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?
The white dwarf will explode completely as a white dwarf supernova.
Pulsars are thought to be _________.
rapidly rotating neutron stars
Which of the following statements about electron degeneracy pressure and neutron degeneracy pressure is true?
Electron degeneracy pressure is the main source of pressure in white dwarfs, while neutron degeneracy pressure is the main source of pressure in neutron stars