Chapter 22 Neutron Stars and Black Holes
The mass range for neutron stars is:
1.4 to 3 solar masses.
The Schwartzschild radius for a 12 solar mass star is:
36 km.
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
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
A proposed explanation for gamma-ray bursters is:
A)hypernova-making black holes and bi-polar jets. B) coalescence of a neutron star binary. C) collisions between two white dwarfs. D) Both A and B ARE POSSIBLE.
The observed slowing of a clock in the vicinity of a black hole is a prediction of:
General relativity.
What explanation does general relativity provide for gravity?
Gravity is the result of curved spacetime.
What would happen if more mass was added to a 1.4 solar mass neutron star?
It could eventually become a black hole, via a hypernova explosion.
What compelling evidence links pulsars to neutron stars?
Only a small, very dense source could rotate that rapidly without flying apart.
What are X-ray bursters?
They are neutron stars on which accreted matter builds up, then explodes in a violent nuclear explosion.
Which of these does NOT exist?
a 6.8 solar mass neutron star
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.
The equivalence principle says that a person in an elevator that is in free fall feels the same acceleration as:
a person in space, far from any gravitational source accelerating at g.
The average density of neutron stars approaches:
about 1017 kg/m3, similar to the density of atomic nuclei.
If light from a distant star passes close to a massive body, the light beam will:
bend towards the star due to gravity.
An observer on a planet sees a spaceship approaching at 0.5c. A beam of light projected by the ship would be measured by this observer to travel at:
c.
Two important properties of young neutron stars are:
extremely rapid rotation and a strong magnetic field.
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.
Relatively long duration gamma-ray bursts are produced by:
hypernovae.
In the Lighthouse Model,
if the beam sweeps across us, we will detect a pulse of radiation.
As a spaceship's velocity gets closer to the speed of light:
its length will decrease and its clock will run more slowly.
The largest known black holes:
lie in the cores of the most massive galaxies.
A method for identifying a black hole is to:
look for their effects on nearby companions.
In a neutron star, the core is:
made of compressed neutrons in contact with each other.
An object more massive than the Sun, but roughly the size of a city, is a:
neutron star.
To which of these phenomena are X-ray busters most similar?
novae
You would expect millisecond pulsars to be:
part of a binary system.
Neutron stars do NOT have:
rotation periods comparable to the Sun's.
Pulsars:
spin very rapidly when they're young.
A critical difference between millisecond and normal pulsars is that:
the millisecond ones are speeding up, but normal pulsars slow down over time.
The key to identifying a black hole candidate in a binary system is that:
the unseen companion in the system must have a sufficiently high mass.
As a spaceship nears an event horizon, a clock on the spaceship will be observed:
to run slowly.
Neutron stars and black holes are formed by:
type II supernovae.
Neutron stars have:
very strong bi-polar magnetic fields.
If the Sun were replaced by a one solar mass black hole:
we would still orbit it in a period of one year.