AST 112 - Chapter 23 - Week 5

Spring 2025 | Exam 2

What is the maximum mass that a White Dwarf star can have before it collapses?

1.44 solar masses

What principle prevents electrons in a White Dwarf from occupying the same space?

the Pauli Exclusion Principle

How does the mass of a White Dwarf affect its radius?

the radius decreases as the mass increases

What is the ultimate fate of a White Dwarf if it’s left to its own devices?

It cools and dims nearly indefinitely

What prevents the core of a low mass star from collapsing further once it has stopped fusing Carbon?

Electron degeneracy pressure

What is the minimum mass a star must have for its core to reach temperatures sufficient to fuse Carbon without becoming electron degenerate?

Eight solar masses

What phenomenon occurs when protons and electrons combine during the collapse of stars below twenty solar masses?

Neutrons are produced

Why does the core of a massive star eventually collapse?

Fusing iron costs energy, this leads to no energy production to replace what is lost

How is the energy that is required to blow up a star in a supernova explosion generated?

The collapse releases gravitational potential energy

What is the significance of supernova in the context of galactic evolution?

They contribute to nucleosynthesis

What objects are generally left behind by stars after their deaths? (except a particular class of extremely massive stars)

Compact objects

What are the three types of Compact objects?

White dwarfs, neutron stars, and black holes

Who discovered Pulsars? In what year?

Jocelyn Bell; 1967

What is unique about the Type 1a Supernova regarding the White Dwarf?

The Carbon and Oxygen in the White Dwarf are entirely burned, completely destroying the star

What is a Pulsar?

A rapidly rotating neutron star that emits radio waves

Novae differ from dwarf novae in that…

Novae involve explosive hydrogen fusion on the surface of a White Dwarf