Allison Thompson Chapter 13 Quiz

1. What is a white dwarf?

 White dwarfs are the remaining cores of dead stars. Electron degeneracy pressure supports them against gravity. White dwarfs cool off and grow dimmer with time. White dwarfs with the same mass as the sun are the same size of Earth. Higher mass white dwarfs are smaller. Quantum mechanics says that electrons must move faster as they are squeezed into a very small space. As a white dwarfs mass approaches 1.4m its electrons must move at nearly the speed of light. Because nothing can move faster than light a white dwarf cannot be more massive than 1.4.

1. What can happen to a white dwarf in a close binary system?

 A star started with less mass gains mass from its companion. Mass falling toward a white dwarf from its close because. has Some angular motion. The matter therefore orbits the white dwarf in an acceleration disk.

 

1. What is a neutron star?

 A neutron star is the ball of neutrons left behind by a massive star supernova.

1. How were neutron stars discovered?

 Using a radon telescope in 1967 Jocelyn Bell noticed a regular pulse.

1. What can happen to a neutron star in a close binary system?

 Matter falling toward a neutron star forms an acceleration disk.

1. What is a black hole?

 A black hole is an object that’s so powerful that not even light can escape.

1. What would it be like to visit a black hole?

 Time passes more slowly near the event horizon

1. Do black holes really exist?

 Needs to measure mass. use orbital properties of companion measure velocity and distance of orbiting gas.

1. What causes gamma ray bursts?

 Brief bursts of gamma rays coming from space were first detects in the 1960s.

1. What did Jocelyn Bell discover?

Neutron Stars