1. All about Stars
Sections 9.2 & 9.4

2. Star Brightness
Stars are giant balls of hot gases that produce and emit energy (much In the form of visible light)
The total amount of energy produced by a star per second is called luminosity.
Things appear brighter when they are closer.

3. Star Colour & Temperature
The colour gives scientists an indication of the temperature.

4. The Mass of a Star
The sun has a mass of 2.0 x kg and this is one solar mass
Star masses range from approx. 0.1 to 120 solar masses!

5. Life Cycle of a star

6. Star beginnings
A star has its beginning deep inside a massive cloud of interstellar gases (mainly hydrogen) and dust called a nebula.
A star is formed when parts of the nebula collapse on themselves

7. protostars
Massive concentration of gas and dust thought to eventually develop into a star after the nebula collapses.
Overtime a protostar becomes a tightly packed sphere of matter which increases its gravity. This allows nuclear fusion to begin.

8. Nuclear Fusion Occurs at 15 million c
Hydrogen atoms “fuse” to make helium atoms

9. The Death of A star Medium Stars (SUN) red giant  White Dwarf
When H runs out the flow of energy slow. The core contracts and gets hotter forming a red giant.
When nuclear fusion stops the outer layers of the star drift away and the core is the only part left (white dwarf)

10. Large Stars  Supernovas
When fusion stops the star collapses under its own gravity.
The explosion sends out shockwaves when it explodes (supernova)
Neutron Star – dense star made of neurons (initial star solar masses)
Black Hole – dense quantity of matter in space from which no light or matter can escape (initial star greater than 30 solar masses)

11. A Summary

12. Today’s Tasks
Pg. 373 #1, 3, 7, 9
Pg. 382 #6