Chapter 22 review

A neutron star is about the same size as

A U.S. city

Which of the following is NOT a characteristic feature of a neutron star?

A radius about the size of the Earth's

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

False

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

False

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

False

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

False

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

False

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

False

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

False

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

False

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

False

What process is responsible for producing the rapid spin rate of millisecond pulsars?

Gas spiraling in from a nearby companion transfers angular momentum to the pulsar, increasing the rate of its rotation.

What will happen to an isolated neutron star that accumulates more than about 3 solar masses of material?

It will overcome the neutron degeneracy in its interior and form a black hole.

Why aren't all young neutron stars seen as pulsars?

Only some neutron stars are oriented so that their beams sweep in the direction of Earth.

At what stage of its life will our Sun become a black hole?

The Sun will never become a black hole

Why does the existence of planets around a millisecond pulsar come as a surprise?

The supernova explosion that formed the pulsar would have blown away any planets originally there.

What do the observed locations of gamma-ray bursts tell us about them?

They must be extra-galactic because they occur everywhere in the sky.

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

True

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

True

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

True

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

True

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

True

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

True

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

True

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

True

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

True

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

True

Which of the following is NOT a reason that observable pulsars are found at the centers of some, but not all, supernova remnants?

Type II core-collapse supernovae do not leave behind rotating neutron stars.

Gamma-ray bursts are observed to occur

approximately uniformly over the entire sky

What keeps light (and all other forms of radiation) from escaping a black hole?

gravity

The X-ray emission from a neutron star in a binary system comes mainly from

heated material in an accretion disk around the neutron star.

A neutron star's immense gravitational attraction is due primarily to its small radius and

large mass

Black holes result from stars having initial masses

more than 25 times the mass of the Sun.

What have astronomers detected in the center of the Crab Nebula?

neutron star

X-ray bursters are caused by a process similar to the process in which other object?

nova

If the Sun were replaced by a 1-solar-mass black hole, what would be the gravitational pull of the black-hole "Sun" on Earth?

same

The most rapidly "blinking" pulsars are those that

spin fastest

What defines the event horizon of a black hole?

the radius at which the escape speed equals the speed of light