Astronomy Ch. 22
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.
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 are the three possible outcomes of stellar evolution? Describe each possibility, differentiating their means of formation and their subsequent properties. Which stars on the Main Sequence are thought to end up in each of these forms?
If less than 1.4 solar masses the final stage of a star's life will be a white dwarf. This forms as a remnant of a red giant which has blown off a planetary nebula. At 1.4 to 3 solar masses, the remnant will be a neutron star. This is generally the result of a Type II supernova explosion. Above three solar masses, the collapse produces a black hole.
What makes the Crab Nebula supernova remnant unusual as a supernova remnant?
It is the remnant of a supernova observed by humans.
With what objects do many of the millisecond pulsars appear to be associated, and
Many lie in globular clusters, which are very old. Because the globular clusters are also crowded, the chance of close binary mass transfers is also greater, which may explain how the old neutrons stars are sped back up in spin.
What compelling evidence links pulsars to neutron stars?
Only a small, very dense source could rotate that rapidly without flying apart.
What would happen if mass is added to a 1.4 solar mass white dwarf?
The star would erupt as a carbon detonation (type I) supernova.
Three terrestrial-sized planets in orbits of a fraction of an AU have been found near
a millisecond pulsar.
The supernova of 1054 AD produced:
a pulsar with a period of 33 milliseconds, visible optically.
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.
f 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.
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.
In the Lighthouse model:
if the beams sweeps across us, we can observe the pulse.
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.
Which of the following can actually escape from inside a black hole's event horizon?
none of the above
To which of these phenomena are X-ray busters most similar?
novae
Pulsars....
spin very rapidly when they're young.
While most neutron stars are also pulsars, an older "bare" neutron star was captured in rapid motion only 200 lightly years distant by:
the Hubble Space Telescope.
As a spaceship nears an event horizon, a clock on the spaceship will be observed
to run slowly.
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.