UVU Astronomy 1040-004 Exam 3

Accretion is stuff that spins around a Black Hole.

GLOBULAR STAR CLUSTERS are all of these.

There may be Super-Massive Black Holes in the centers of some galaxies.

Conservation of Angular Momentum is why there is such a difference in rotation.

Supernova 1987A blew up 160,000 years prior.

Jets are all of these.

Nuclear Fusion is what makes a star a star.

The Lighthouse Model

As a star burns helium into carbon

Nature forbids gravity to get whatever it wants. It has to expel stuff back out into space. Expelled by JETS.

Before a star collapses to a Neutron Star it probably rotates about once every 25 days.

White Dwarf Supernova - occur in binary systems in which one is a white dwarf.

Stars can then become unstable and turn into Pulsating Stars like RR Lyrae Variables or Cephied Variables.

When the temperature reaches 10,000,000 K in the core all of these things happen.

Supernova: a stellar explosion that marks the end of a star's evolution.

In about 2 billion years our Sun will

Stars similar to our sun start to die when they start to run out of Helium.

Iron is so incredibly stable that once a High Mass Star gets to iron in its core it blows up.

Once carbon is created it is "one foot in the ground".

After a Supernova the exposed core is seen as a Neutron Star or if more than 3_☉ the core becomes a Black Hole.

OPEN STAR CLUSTERS are all of these.

The core pressure then surges & lifts the outer layers from the star in a titanic explosion - a SUPERNOVA!

Black Holes

Star Clusters are useful to astronomers because the clusters contain stars that are

Dr. Haisch studies this phase. (Protostars forming.)

A Neutron Star can possibly become a Black Hole.

Large Mass Stars do NOT become White Dwarves, only Neutrons or Black Holes.

High Mass Stars stay on the main-sequence for about 10 million years or so.

Pulsars are all of these.

Spagettification is what happens to you if you get sucked into a Black Hole. RIP.

Conservation of Angular Momentum is the smaller something gets the faster it spins.

You can't put Step 1 on an H-R Diagram because..

The iron core collapses due to reduced pressure converting the core into mostly neutrons.

Distance is the most fundamental thing you can know about a star otherwise you will get everything else wrong.

The material that makes up our Sun was once part of

The star then becomes a Red SUPER Giant after millions of years of helium fusion.

As a star evolves into a Red Giant

What keeps a star stable?

When a High Mass Star exhausts the Hydrogen fuel in its core

Nucleosynthesis is the cosmic formation of atoms more complex than the hydrogen atom.

When you introduce mass into space it bends.

A star with an iron core is

Neutron stars that appear to us as Pulsars rotate about once every second.

Our Sun began its life like all stars do. As a molecular hydrogen cloud.

Low Mass Stars like our Sun remain on the main-sequence for about 10 billion years or longer.

Pulsars were discovered on August 6,1967 by Jocelyn Bell Burnell.

Neutron Stars are all of these.

Our Sun will become a White Dwarf when it dies. It will NOT explode.

Star formation begins in relatively small molecular clouds called Dense Cores.

After most of the hydrogen is fused into helium in a small star,helium fusion begins in an event called the Helium Flash

Brown Dwarfs are all of these.

In about 1 million years a small, hot, dense Protostar forms.

A Protostar is a very young star that is still gathering mass from its parent molecular cloud.

More about White Dwarfs:

When helium is depleted, fusion of heavier elements begins in a process called Nucleosynthesis.

Forces the hold collapsing stars together:

Singularity is all of these.

Pulsars provide the most precise natural cosmic clocks known to date. 

Helium is compressed & heats up & expands into a Red Giant.

If you get sucked into a Black Hole you go to Singularity.

M _☉ = Solar Mass

On July 4, 1054 Astronomers in China witnessed a Supernova within our own galaxy.

Helium Flash is a very brief thermal runaway nuclear fusion of large amounts of helium into carbon.

Nova: Stellar explosion - always involves a white dwarf.

The evolution of High Mass Stars is the same as Small Mass stars first 5 steps.

Angular Momentum does 2 important things:

After creating a planetary nebula it leaves an exposed core called a White Dwarf.

White Dwarfs also

Bigger mass stars do this a lot faster.

What important event occurred when our Sun was in its outflow phase?

The Chandrasekhar limit (about 1.4 M☉) is the maximum mass of a stable white dwarf star.

This cloud collapses due to gravity and breaks up into many Dense Cores.

If space had no mass it would be flat.

Jets are important because they stop the building process.

Bigger mass stars are born faster because..

If stellar core has more than 3 solar masses after Supernova, then no known force can halt the collapse.

Hydrogen fusion begins in a shell around the core & the star expands into a Red Giant.