Deck 22: Neutron Stars and Black Holes: Strange States of Matter

Question 1

Gamma-ray bursts seem to come primarily from neutron star binaries in the plane of our ownMilky Way Galaxy.

Answer 1

False

Question 2

If the rate at which a pulsar is slowing down is found, this helps us find the time at which itwas produced by the supernova.

Answer 2

True

Question 3

Besides direct formation of a black hole in a hypernova, some think that mergers betweenneutron stars can create even longer-lived gamma-ray bursts as well.

Answer 3

False

Question 4

The Schwarzschild radius of a black hole is about 3 km per solar mass; it is amazingly linearover a wide range of masses.

Question 5

The life ending event for a very massive star can result in long duration gamma-ray bursts.

Question 6

Short duration gamma-ray bursts are explained as the merger of two neutron stars.

Question 7

Like most pulsars, the Crab Nebula neutron star is known only by its radio pulses.

Question 8

Neutron stars seem to travel a good deal faster than most stars in orbit about the Galaxy.

Question 9

There is no difference in the light curve for a hypernova and the light curve for a supernovaII; the two events are distinguished from other properties.

Question 10

X-ray bursters are similar to novae, except the collapsed star is a neutron star, not a whitedwarf.

Question 11

Any main sequence star over 25 solar masses will probably retain enough matter in its coreafter its type II supernova or hypernova event to make a black hole.

Question 12

X-ray bursts and gamma-ray bursts have the same distribution pattern in the sky.

Question 13

All neutron stars must begin as millisecond pulsars just after their supernova creation.

Question 14

The escape speed for a black hole's event horizon is the speed of light.

Question 15

All neutron stars are pulsars, but not all pulsars are neutron stars.

Question 16

The density of a neutron star is comparable to the density of an atomic nucleus.

Question 17

Astronomers believe that gamma-ray bursters emit radiation equally in all directions.

Question 18

Newly formed neutron stars have weak magnetic fields which strengthen over time, due to theconservation of angular momentum.

Question 19

A system of terrestrial-sized planets has been detected in orbit around a millisecond pulsar.

Question 20

Special relativity says that c, the speed of light, is the maximum velocity for both matter andenergy in our universe.

Question 21

Very rapid time variations help establish the tiny size of many X-ray sources, showing theymust be collapsed objects of some kind.

Question 22

Only neutrinos can go faster than the speed of light, as proved by Supernova 1987A.

Question 23

Neutron stars are formed by:

A)the star formation process.
B)mass transfer in binary star systems.
C)novae.
D)type I supernovae.
E)type II supernovae.

Question 24

In a neutron star, the core is:

A)made of compressed neutrons in contact with each other.
B)electrons and protons packed so tightly they are in contact.
C)constantly expanding and contracting.
D)primarily iron and silicon.
E)no longer rotating.

Question 25

An object more massive than the Sun, but roughly the size of a city, is a:

A)supernova remnant.
B)white dwarf.
C)brown dwarf.
D)neutron star.
E)red dwarf.

Question 26

Two important properties of young neutron stars are:

A)extremely slow rotation and a strong magnetic field.
B)extremely rapid rotation and a weak magnetic field.
C)extremely rapid rotation and a strong magnetic field.
D)no rotation and a weak magnetic field.
E)no rotation and no magnetic field.

Question 27

Which of these does NOT exist?

A)a million solar mass black hole
B)a 6 solar mass black hole
C)a 6.8 solar mass neutron star
D)a 1.0 solar mass white dwarf
E)a 0.06 solar mass brown dwarf

Question 28

Neutron stars do NOT have:

A)masses greater than 1.4 solar masses.
B)sizes comparable to large cities.
C)strong magnetic fields.
D)large surface gravities, compared to the Sun.
E)rotation periods comparable to the Sun's.

Question 29

What makes the Crab pulsar somewhat unusual among pulsars in general?

A)It is the most intense source of X-rays in the sky.
B)It is the fastest pulsar known.
C)It is the oldest pulsar observed.
D)Its period is not regular like other pulsars.
E)It is rather bright at visible wavelengths.

Question 30

At the event horizon, time stops.

Question 31

What would happen if mass is added to a 1.4 solar mass white dwarf?

A)The star would explode as a nova.
B)The star's radius would increase.
C)The star would immediately collapse into a black hole.
D)The star would erupt as a carbon detonation (type I)supernova.
E)The core would collapse as a type II supernova.

Question 32

Neutron stars have:

A)very strong bipolar magnetic fields.
B)weak or non-existent magnetic fields.
C)periods of days or weeks.
D)monopolar fields that switch polarity every rotation.
E)no relation to pulsars.

Question 33

The energy from the accretion disk around a black hole would show gravitational redshiftdue to its immense gravity and tidal distortion of space there.

Question 34

The vast majority of pulsars are known only from their pulses in:

A)X-rays.
B)gamma rays.
C)visible light.
D)microwaves.
E)radio waves.

Question 35

The average density of neutron stars approaches:

A)a million times that of normal matter.
B)a million times that of even a white dwarf.
C)about 1017 kg/m3, similar to the density of atomic nuclei.
D)about 1018 times that of water.
E)infinity.

Question 36

What makes the Crab Nebula supernova remnant unusual as a supernova remnant?

A)It is the biggest supernova remnant visible.
B)It is the remnant of a supernova that was observed in the 20th century.
C)It is the nearest supernova remnant.
D)It is the oldest supernova remnant known.
E)It is the remnant of a supernova observed by humans.

Question 37

Pulsars:

A)spin very rapidly when they're young.
B)are the cause of gamma-ray bursts.
C)spin very slowly when they're young, and gradually spin faster as they age.
D)generally form from 25 solar mass stars.
E)emit radio waves in all directions.

Question 38

Special relativity predicts that light bends near dense objects.

Question 39

Mercury's orbital precession is adequately explained by Newton's Law of Gravity.

Question 40

What compelling evidence links pulsars to neutron stars?

A)Both pulsars and neutron stars can be found in globular star clusters.
B)Pulsars are known to evolve into neutron stars.
C)Only a small, very dense source could rotate that rapidly without flying apart.
D)Pulsars are always found in binary systems with neutron stars.
E)Both pulsars and neutron stars have been discovered near the Sun.

Question 41

The supernova of 1054 AD produced:

A)a remnant still visible to the naked eye, the Crab Nebula, M-1.
B)a pulsar with a period of 33 milliseconds, visible optically.
C)the closest known neutron star to our Sun.
D)the most famous black hole.
E)no remaining visible trace, as it was a type I supernova.

Question 42

What are X-ray bursters?

A)They are the central sources of energy for planetary nebulae.
B)They are very massive stars that explode as supernovae, emitting bursts of X-rays and gammarays in the process.
C)They are rapidly rotating black holes whose precession points their poles toward us onoccasion.
D)They are violent energy sources known to lie at the heart of the Milky Way and similarmassive galaxies.
E)They are neutron stars on which accreted matter builds up, then explodes in a violent nuclearexplosion.

Question 43

While most neutron stars are also pulsars, an older "bare" neutron star was captured in rapidmotion only 200 light-years distant by:

A)Arecibo Radio Observatory.
B)the Keck Telescopes used as an interferometer.
C)the Chandra X-ray Observatory.
D)the Hubble Space Telescope.
E)the Spitzer Infrared Space Telescope.

Question 44

In the lighthouse model:

A)pulsars are observable only if they lie in the galactic plane.
B)pulsars are navigational devices created by interstellar navigators as discovered by JocelynBell in 1967.
C)all pulsars have their poles pointed directly at us or they would not be observable.
D)if the beam sweeps across us, we can observe the pulse.
E)the period of pulsation must speed up as the neutron star continues contracting.

Question 45

Short duration gamma-ray bursts are thought to be caused by:

A)novae.
B)supernovae.
C)hypernovae.
D)mergers of white dwarfs.
E)mergers of neutron stars and/or black holes.

Question 46

In contrasting the distribution of the X-ray and gamma-ray bursts, we find:

A)gamma-ray bursts are far closer to us, so they appear more luminous.
B)gamma-ray bursts are far beyond our Galaxy, at cosmological distances, and spread all overthe sky, not in the plane of our Galaxy.
C)gamma-ray bursts are more closely associated with open than globular clusters.
D)gamma-ray bursts can repeat, while the X-ray bursts do not.
E)gamma-ray bursts can be observed from the ground, but X-rays are blocked by the ionospherefor ground-based observers.

Question 47

X-ray bursters occur in binary star systems. The two types of stars that must be present tomake up such an object are:

A)a white dwarf and a neutron star.
B)a contact binary system of two red giants.
C)a white dwarf and a main sequence star.
D)a main sequence or giant star and a neutron star in a mass transfer binary.
E)two neutron stars in a mass transfer binary.

Question 48

A proposed explanation for gamma-ray bursters is:

A)hypernova-making black holes and bipolar jets.
B)coalescence of a neutron star binary.
C)collisions between two white dwarfs.
D)Both A and B are possible.
E)All three are possible.

Question 49

The Swift satellite observes what portion of the electromagnetic spectrum?

A)gamma ray
B)X-ray
C)ultraviolet
D)optical
E)all of the above

Question 50

In the Lighthouse Model:

A)the star literally turns on and off like a lighthouse beacon.
B)all pulsars must have their poles pointed directly toward us.
C)if the beam sweeps across us, we will detect a pulse of radiation.
D)the period of pulsation must speed up as the neutron star continues collapsing.
E)the period of pulsation slows down due to the drag of the remnant on its field.

Question 51

You would expect millisecond pulsars to be:

A)part of a binary system.
B)isolated in space.
C)rotating slowly.
D)most common in open clusters.
E)collapsing rapidly.

Question 52

Redshift measurements of the visible afterglow of a gamma-ray burst show that these objectsare:

A)in the solar neighborhood.
B)in the Milky Way Galaxy.
C)in the Local Group.
D)billions of light-years away.
E)at the most extreme observable distances.

Question 53

What would happen if more mass was added to a 1.4 solar mass neutron star?

A)It would erupt as a Type I supernova.
B)It could eventually become a black hole, via a hypernova explosion.
C)It would grow larger, temporarily becoming a red giant again.
D)All of its protons and electrons would turn into quarks.
E)It would blow off mass as a gamma-ray burster.

Question 54

Which of the following is NOT a property of a pulsar?

A)period of 1.34 seconds
B)over time, the period is gradually increasing
C)emissions only in the visible part of the spectrum
D)each pulse consisting of a 0.01 second burst of radiation
E)time interval between pulses is very uniform

Question 55

Almost half of all known millisecond pulsars are found in what type of object?

A)giant molecular clouds
B)open clusters
C)globular clusters
D)emission nebulae
E)supernova remnants

Question 56

Three terrestrial-sized planets in orbits of a fraction of an A.U. have been found near:

A)Cygnus X-1.
B)a magnetar.
C)Supernova 1987A.
D)a millisecond pulsar.
E)a white dwarf.

Question 57

A critical difference between millisecond and normal pulsars is that:

A)the millisecond ones are not associated with the galaxy, but scattered everywhere.
B)the millisecond ones are speeding up, but normal pulsars slow down over time.
C)the millisecond ones must eventually collapse into black holes.
D)the millisecond ones all have planets, while normal ones do not.
E)millisecond ones are only found in globular clusters, while normal ones are not.

Question 58

Whose work with SETI led to the discovery of pulsars in 1967?

A)Jocelyn Bell
B)Sir Bernard Lovell
C)Anthony Hewish
D)Martin Schwarzschild
E)Stephen Hawking

Question 59

To which of these phenomena are X-ray busters most similar?

A)novae
B)planetary nebulae
C)type I supernovae
D)type II supernovae
E)hypernovae

Question 60

Most pulsars have a measured mass of:

A)about 1.4 solar masses.
B)less than 1.0 solar masses.
C)between 2 and 4 solar masses.
D)5.2 solar masses.
E)greater than 10 solar masses.

Question 61

An observer on a planet sees a spaceship approaching at 0.5c. A beam of light projected bythe ship would be measured by this observer to travel at:

A)0.25c.
B)0.5c.
C)c.
D)1.5c.
E)2.5c.

Question 62

As a spaceship nears an event horizon, a clock on the spaceship will be observed:

A)to run faster.
B)to stop.
C)to run slowly.
D)to run backwards.
E)to run the same as one on Earth.

Question 63

A hypernova creates:

A)a black hole.
B)a pulsar.
C)a neutron star.
D)short-duration gamma-ray bursts.
E)Both B and C are correct.

Question 64

As a spaceship's velocity gets closer to the speed of light:

A)its length will increase and its clock will run more slowly.
B)its length will decrease and its clock will run faster.
C)its length will increase and its clock will run faster.
D)its length will decrease and its clock will run more slowly.
E)None of these will happen.

Question 65

Which of the following can actually escape from inside a black hole's event horizon?

A)neutrinos
B)electrons
C)very high energy gamma rays
D)gravitons
E)none of the above

Question 66

The densely packed neutrons of a neutron star cannot balance the inward pull of gravity ifthe total mass is:

A)less than 1.0 solar masses.
B)greater than Schwarzschild's limit of 3 solar masses.
C)Chandrasekhar's limit of 1.4 solar masses.
D)between 1.4 and 2.0 solar masses.
E)greater than 25 solar masses.

Question 67

The Schwarzschild radius for a 12 solar mass star is:

A)4 km.
B)15 km.
C)36 km.
D)100 km.
E)3000 km.

Question 68

The observed slowing of a clock in the vicinity of a black hole is a prediction of:

A)the Roche Limit.
B)special relativity.
C)general relativity.
D)stellar nucleosynthesis.
E)the Cosmological Principle.

Question 69

From the perspective of an observer in space, time on a spaceship near a strong source ofgravity, such as the Sun, would run:

A)slower.
B)faster.
C)backwards.
D)stop.

Question 70

What can we detect from matter that has crossed an event horizon?

A)gamma-ray bursts
B)radio waves if the matter was traveling fast enough
C)visible light
D)X-rays if the matter was dense
E)nothing

Question 71

According to the special theory of relativity, as the speed of a rocket ship increases, anobserver sees the mass of a spaceship:

A)stay the same.
B)increase.
C)decrease.
D)converted to energy.
E)fluctuate.

Question 72

Which of the following are attracted by gravity?

A)antimatter
B)any object with mass
C)electromagnetic radiation
D)neutrinos
E)all of the above

Question 73

Relatively long duration gamma-ray bursts are produced by:

A)novae.
B)supernovae.
C)hypernovae.
D)neutron star mergers.
E)black hole mergers.

Question 74

The equivalence principle says that a person in an elevator that is in free fall feels the sameacceleration as:

A)a person in an elevator going up with an acceleration of g.
B)a person in space, far from any gravitational source accelerating at g.
C)a person in an elevator going down with an acceleration of g.
D)a person in space, far away from any gravitational source with no acceleration.
E)a person in orbit of Earth accelerating at g upward.

Question 75

A spacecraft moving near the speed of light will appear ________ compared to itsappearance at rest.

A)shortened
B)lengthened
C)widened
D)narrowed
E)unchanged

Question 76

To an observer on Earth, the clock on a spaceship moving at constant, but high velocity,would:

A)run slow.
B)run fast.
C)go backwards.
D)stop.

Question 77

If the Sun were replaced by a one solar mass black hole:

A)all terrestrial planets would fall in immediately.
B)the Earth would still orbit it in a period of one year.
C)the Earth would immediately escape into deep space, driven out by its radiation.
D)clocks on Earth would all stop.
E)life on Earth would be unchanged.

Question 78

What explanation does general relativity provide for gravity?

A)Gravity is the result of curved spacetime.
B)Gravity is directly proportional to the mass of the attracting body.
C)Gravity is inversely proportion to the radius of the body.
D)Gravity is the opposite of the electromagnetic force.
E)Gravity can affect only massive particles, not massless photons.

Question 79

If light from a distant star passes close to a massive body, the light beam will:

A)bend towards the star due to gravity.
B)continue moving in a straight line.
C)change color to a shorter wavelength.
D)slow down.
E)accelerate due to gravity.

Question 80

The mass range for neutron stars is:

A).08 to .4 solar masses.
B).4 to 3 solar masses.
C)1.4 to 3 solar masses.
D)3 to 8 solar masses.
E)6 to 11 solar masses.