R.A.S 14.1-3

Scientists predicted the existence of black holes and found evidence that they exist. Based on what you know about black holes, select all of the correct statements from the following list.

A black hole is a mass that cannot stop collapsing. X-rays emitted by objects about to cross an event horizon can escape a black hole's gravity and be detected. Even light cannot escape the gravitational pull of a black hole. Evidence of black holes has been found in binary systems.

Which of the following describes the gravitational redshift?

A reduction in the energy of photons as they move away from objects.

What was the most distinctive property that led to the discovery of pulsars?

A repeating pattern in the observed data with a precise period.

Why do the millisecond pulsars spin so fast?

Accretion of matter from a nearby binary companion spins them up.

How are neutron stars and white dwarfs similar? How do they differ?

Both eventually cease to shine. Both are compact objects. Both are faint and difficult to detect. Both are produced by dying stars. White dwarfs are produced by the final gravitational contraction of the cores of low- to medium-mass stars. Neutron stars are produced from the collapsing core of a massive star as it undergoes a supernova explosion.

What changes would occur if the sun were replaced with a one-solar-mass black hole?

Earth's orbit would not change and the planets would disappear from view.

______ -mass stars end their lives as neutron stars.

Intermediate

Which of the following is an accurate description of the Schwarzschild radius?

It is the radius to which an object must shrink to become a black hole and is the radius of the event horizon surrounding a black hole singularity.

The most important factor that determines how a star will end its life is

Mass

How does the lighthouse model explain pulsars? The lighthouse model explains pulsars as spinning ______ that emit beams of radiation from their______. As they spin, they sweep the beams around the sky like lighthouses.

Neutron stars; magnetic poles

What observational evidence do we have that stellar-mass black holes really exist?

Some X-ray binaries have unseen objects with masses greater than 3 solar masses.

Why do neutron stars have an upper mass limit?

There is a maximum mass that can be supported against gravity by the outward pressure of degenerate neutrons.

Scientists predicted the existence of neutron stars and found evidence that they exist. Based on what you know about neutron stars, select all of the correct statements from the following list.

When a supernova explodes, the core of the star collapses. Pulsars are spinning neutron stars. Planets have been found orbiting a neutron star. Neutron stars are very small and spin very fast.

If you have weights on both ends of a spinning rod, the spin rate of the rod will _______ as you move the weights closer to the center. This is a consequence of __________ .

increase; conservation of angular momentum