StarsThe life and death of stars in our universe

What are stars?

• A massive ball of plasma and gas fueled by nuclear fusion: Hydrogen Helium Carbon …

What are stars?

• Astronomers learn about stars using the star’s luminosity, color, and motion through space

• Luminosity = energy/time

• Color = light waves emitted from the star (depicts what elements the star is made of).

How are Stars Made?

1. Protostar – A large cloud of dust and particles that begins to contract on itself

How are Stars Made?

2. Main Sequence – A star will fall on the main sequence, depending on its temperature and luminosity.

Life Cycle of a Star

But First…Let’s Get Some Perspective…

But First…Let’s Get Some Perspective…

But First…Let’s Get Some Perspective…

But First…Let’s Get Some Perspective…

But First…Let’s Get Some Perspective…

But First…Let’s Get Some Perspective…

But First…Let’s Get Some Perspective…

The Known Universe

How are Stars Made?Yellow Star Red Giant

• High luminosity• “Smaller” in size

How are Stars Made? Red Giants

• Core gets extremely hot and collapses in on itself, while the outer layers expand

How are Stars Made? Red Giants Planetary Nebula• Red Giants

continue to eject its outer layers.

• Planetary Nebula is an expanding, glowing shell of ionized gas

How are Stars Made? Planetary Nebula White

Dwarfs• The star continues

to eject its outer layers until the core is exposed.

• The core is dead, but still very hot.

• This core is called a White Dwarf.

How are Stars Made?White Dwarfs

• White Dwarfs may become Novae

Life Cycle of a Star

How are Stars Made?Blue Star Red Supergiant

• High luminosity• Large in size

How are Stars Made?Red Supergiant

• High luminosity• Core gets

extremely hot and collapses in on itself, while the outer layers expand

How Are Stars Made?Red Supergiant Supernova• Red Supergiants

run out of fuel (energy) and the core collapses

• This results in a giant explosion

How Are Stars Made? Supernova Neutron Star

• The supernova core becomes more dense as it continues to collapse - fusing protons and electrons into neutrons

How are Stars Made?Neutron Star Black Hole

• Eventually, the neutron star’s core collapses completely

• Black hole = an infinitely dense object whose gravity is so strong, nothing can escape it’s immediate proximity (not even light)