Chapter 13
The supernova that created the Crab nebula and its pulsar was seen on Earth in the year
1054 AD.
What have astronomers detected in the center of the Crab Nebula?
A neutron star
Where are the "hot spots" that create the beams of a pulsar always located?
At the magnetic poles
A proposed explanation for gamma-ray bursters is
Both A and B are possible.
Type _____ supernovae produce no neutron stars, only ejected debris.
I
What makes the Crab Nebula pulsar unusual among other pulsars?
It is relatively bright in shorter wavelengths, like visible and X-rays.
What is the process that creates a neutron star?
It is what is left after the explosion of a massive star in a Type II supernova.
Why is light increasingly redshifted as the light source nears a black hole?
It must expend energy to escape the gravitational pull of the black hole.
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.
Who discovered the first four pulsars?
Jocelyn Bell
Most properties of a neutron star are extreme in comparison to normal stars. Which of the following properties is NOT unusual when compared to a normal star?
Mass
What process is responsible for producing the rapid spin rate of millisecond pulsars?
Matter spiraling in from a nearby companion transfers angular momentum to the pulsar, increasing the rate of its rotation.
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.
The properties of neutron stars help explain their relationship to pulsars. Which of the following is (are) important when explaining how a pulsar generates the radiation we detect?
The magnetic field lines in a neutron star are squeezed close together, creating an extremely intense magnetic field. Neutron stars can rotate extremely rapidly, as quickly as 30 times a second or more.
Which of these is not an argument for Cygnus X-1 being a black hole?
The mass of the visible star is greater than that of the X-ray source.
Which of the following statements correctly describes the observed characteristics of gamma-ray bursts?
They are brief, very intense, nonrepeating, sudden releases of energy that appear to come from very large distances outside our Galaxy.
Which statement about gamma ray bursters is not correct?
They are scaled up X-ray bursters, with more massive objects involved.
Which of these does not exist?
a 1.5 solar mass white dwarf
A neutron star is about the same size as
a U.S. city.
A hypernova creates
a black hole.
X-ray bursters occur in binary star systems. The two types of stars that must be present to make up such an object are
a main-sequence or giant star and a neutron star in a mass transfer binary.
Gamma-ray bursts are observed to occur
approximately uniformly over the entire sky.
In a hypernova, a very energetic supernova creates a
black hole.
Two important properties of young neutron stars are
extremely rapid rotation and a strong magnetic field.
According to Figure 13.3 in the textbook (Pulsar Model), the beam of a pulsar is emitted
from the magnetic poles.
Two-thirds of all known millisecond pulsars are found in what type of object?
globular clusters
The densely packed neutrons of a neutron star cannot balance the inward pull of gravity if the total mass is
greater than Schwartzschild's limit of 3 solar masses.
The best place to search for black holes is in a region of space that
has strong X-ray emission.
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.
Which are the two most popular candidates for gamma-ray bursters?
hypernova making a black hole, and merger of two neutron stars
In the Lighthouse Model,
if the beam sweeps across us, we will detect a pulse of radiation.
The largest known black holes
lie in the cores of the most massive galaxies.
In a neutron star, the core is
made of compressed neutrons in contact with each other.
Mass added to a pulsar from its companion can speed it up into a(n) _____ pulsar.
millisecond
An object more massive than the Sun, but roughly the size of a city, is a
neutron star.
What can we detect from matter that has crossed an event horizon?
nothing
X-ray bursters are caused by a process similar to the process in which other object?
nova
Most pulsars are observed only as ________ sources.
radio
The most rapidly "blinking" pulsars are those that
spin fastest.
Pulsars
spin very rapidly when they're young.
What is Cygnus X-1?
the leading candidate for an observable black hole binary system
What defines the event horizon of a black hole?
the radius at which the escape speed equals the speed of light
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?
the same
