This is how most stars with close companions live.
What is like isolated stars?
100
The white dwarf limit.
What is 1.4 M(Sun)? No white dwarf can be more massive than this because electrons would have to reach the speed of light.
100
A pulsar.
What is a neutron star left behind by a supernova that is rapidly spinning (because of conservation of angular momentum) whose magnetic fields direct beams of radiation out along magnetic poles as they rotate (like a lighthouse)?
100
Event horizon.
What is the boundary between the inside of a black hole and the universe; the point of no return where escape velocity equals the speed of light?
200
The kind of force that two stars in a close binary exert on one another.
What is tidal force?
200
Composition, density, and size of a white dwarf.
What is...composition reflects products of star's final nuclear-burning stage, density is very high, and more massive white dwarf means smaller size?
200
X-ray binary.
What is a binary system that contains an accreting neutron star? (The accretion is hotter and more luminous and so it radiates X rays)
200
Einstein's GTR tells us that what we perceive as gravity arises from this.
What is the curvature of spacetime?
300
This is what happens when the more massive companion star runs out of hydrogen.
What is it stars expanding and gas from its outer layers spills over to its companion?
300
This is what can happen to a white dwarf in a close binary system.
What is it can gain mass from its companion if it's main sequence or a giant? This mass has a small orbital velocity that grows so it forms an accretion disk that can provide the white dwarf with a new source of energy if it keeps going.
300
X-ray burst.
What is an eruption of an accreting neutron star caused by the sudden ignition of helium fusion on the neutron star at 100 million K?
300
Schwarzschild radius. (Interesting fact: this means like "black shield" in German which I know because Schildkroete means turtle but literally translates to "ugly frog with a shield" or something and I used to have a pet turtle that I had to write about in German class)
What is the radius of the event horizon that only depends on mass? (larger mass = larger radius)
400
This is when mass exchange occurs.
What is when the giant grows so large that its tidally distorted outer layers succumb to the gravitational contraction of the smaller companion star
400
White dwarf novae.
What is when white dwarf's gravity compresses the accreted material enough that it reaches 10 million K and hydrogen fusion suddenly ignites? This generates heat and pressure that ejects most of the accreted material which expands outward and creates a nova remnant.
400
X-ray burster.
What is a binary system that produces X-ray bursts?
400
How black holes are formed.
What is when degeneracy pressure supporting iron core doesn't succeed in blowing away all of the outer layers and matter falls onto the neutron star, bringing it past the neutron star mass limit between 2-3 M(Sun), so gravity crushes it and nothing can stop it?
500
The ___ star gains mass at the ___ expense.
What is the smaller companion star and the giant's?
500
White dwarf supernova.
What is when the white dwarf accretes so much mass that it approaches the white dwarf limit and the temperature gets high enough for carbon fusion to ignite, denotating a white dwarf supernova explosion?
500
The dominant pressure in a neutron star.
What is neutron degeneracy pressure?
500
Where supermassive black holes are theoretically located.