Novae and Supernovae Test Review

Flashcards for test review

What do Nova and Type Ia Supernova have in common?

Both occur in a binary system and involve the explosion of a white dwarf.

Define Nova.

An explosion of a star.

Define Type Ia Supernova.

When a white dwarf accumulates enough mass from a companion star, creating a thermonuclear reaction that completely destroys the star.

How do Nova and Type Ia Supernova differ?

Nova is an explosion on the surface of a star, while a Type Ia Supernova completely destroys the star.

What is the Chandrasekhar mass?

The amount of mass a dwarf star must accumulate to create a thermonuclear reaction and collapse due to its gravity (~1.4 solar masses).

How do astronomers use Type Ia Supernovae to determine distances of faraway galaxies?

By comparing its luminosity to other stars.

Where does most of the iron in the universe come from?

Supernovas.

Why don't we need to worry about the Sun going supernova?

The sun is not big enough.

How massive do stars have to be to undergo Type II Supernova?

8 solar masses.

What happens in Stage 1 of Massive Stellar Evolution?

A massive star goes off the main sequence and becomes a supergiant.

What happens in Stage 2 of Massive Stellar Evolution?

A helium flash occurs and the star becomes blue.

What happens in Stage 3 of Massive Stellar Evolution?

The core runs out of He and H and becomes a red star again- H and He shells burn.

What happens in Stage 4 of Massive Stellar Evolution?

Carbon in the core fuses and creates iron, magnesium, and neon- bigger metals.

What happens in Stage 5 of Massive Stellar Evolution?

Carbon runs out and fusion stops- carbon shell burning begins.

What happens in Stage 6 of Massive Stellar Evolution?

Oxygen, neon, silicon, and magnesium fuse and all their shells will burn leading to a supernova explosion.

What happens to the iron protons and electrons in the core of a massive star when iron will not fuse?

They combine to form neutrons which create a heave neutron core which creates a neutron star.

What final step causes the massive star to go Type II Supernova?

The core collapses and rebounds off the neutron core.

List the elements that undergo fusion in a massive star in order.

H, He, Carbon, neon, oxygen, silicon, iron.

What is nucleosynthesis?

When high temperatures cause fusion and create heavier metals.

After a massive star goes Type II Supernova, what are the 2 possible remnants and describe what core mass will create them?

A neutron star (under 3 masses): Is composed of neutrons. A black hole (over 3 masses): The core is very dense and collapses into itself.

What is a pulsar?

A young neutron star that spins rapidly and has a strong magnetic field and a lot of mass for being so small.

Give 2 reasons why neutron stars are not always pulsars.

1. Older 2. Don't point radiation towards earth.

Describe the Schwarzschild radius.

The distance of an object where light cannot escape- the center of the blackhole.

Describe the Event Horizon.

The edge of the blackhole.

Describe the Singularity.

The point where the fabric of time bends and the center of the blackhole- the point behind the blackhole.

What type of explosion will occur when stars are 100 times more massive than the Sun?

Pair instability supernova - will explode completely, leaving no remnants.

What was significant about the neutrinos from the 1987 Supernova?

The first supernova where neutrinos were first detected- proving that the core collapsed into itself.

What is spagettification?

If someone were to go into a black hole, their body would be stretched like spaghetti- this applies to any other object.

How are black holes detected?

The emission of radiation (x-rays).