Ch 25.2 Stellar Evolution

Objectives:

1. What stage marks the birth of a star?

When the protostar reaches 10 million degrees K and nuclear fusion occurs.  The star is “self-sufficient” and producing its own energy.
2. Why do all stars eventually die?

All stars eventually die because they run out of fuel
3. What stages make up the life cycle of a low, medium, and high mass star?

This chart lists the stages but does not include details you will be expected to know.

Interesting videos

What will happen to the Earth when the sun dies?

Life of a Star:  12 billion years in 6 minutes

When stars go boom

 NASA | Fermi Proves Supernova Remnants Produce Cosmic Rays

Full version Death Stars

http://www.youtube.com/watch?v=hr7gYxghZrg

Life and Death of Stars

http://www.youtube.com/watch?v=mzE7VZMT1z8

Part 1

Part 2

Part 3

Part 4

Part 5

Life cycle of a Medium mass star

Nebula
Cloud of dust and gas

Protostar
A developing star, not yet hot enough for nuclear fusion to occur

Main sequence star
Core temp is at least 10 million K and nuclear fusion occurs
Star is a stable size as gravity pushing in is offset by gas pressure pushing out

Red Giant
All hydrogen in core gets consumed so star collapses causing the temp. to increase
Forms b/c zone of nuclear fusion moves outward

Planetary Neblua
During the collapse from a red giant to a white dwarf, a glowing cloud of gases is emitted

White dwarf
Remains of low and medium mass stars
Extremely small star w/ density greater than any substance on Earth

Black dwarf
A white dwarf that has cooled such that it is no longer emitting light