1. STARS
Mrs. Anton

2. Similarity - human and stars life cycle

3. Star Facts Our sun – nearest star Gases, gives of heat and light
Billions of stars
Look like points because far away
Stars different colors
Rigel – blue
Betelgeuse – red
Our sun - yellow

4. Birth of a Star Most stars – hydrogen and helium Steps towards birth
1. Nebula - spinning gas and dust
2. Gravity causes it to shrink until a disk
3. Protostar - center of disk, becomes star
4. Shrinks and heat increases
5. When temp. high enough – gives off light
and becomes a star when hydrogen changes to helium

5. After Birth
Lets Review: Protostar becomes a real star when it is hot enough for hydrogen to change to helium and give off light THEN Enter 2nd stage – Main Sequence Star Leaves this stage when all fuel (gas) is used up Shrinks AND temperature increases Helium changes to carbon

6. Look at this while studying the next slide

7. Protostar-Massive Star
Nebula
Protostar-Massive Star
Main Sequence
Red Supergiant
Supernova
Neutron Star Black Hole
Medium Size Star Nebula Protostar -Average star Main Sequence Red Giant Planetary Nebula White Dwarf

8. Magnitude Magnitude – measure of star brightness
Apparent Magnitude – Brightness as seen from earth
Absolute Magnitude – Actual brightness as if all the stars are the same distance away

9. Shows relationship between absolute magnitude and temperature
Shows relationship between absolute magnitude and temperature .Remember color changes when temperature changes.
A star’s place on diagram depends on temperature and absolute magnitude.
Most stars fall in a band that runs from the upper left to the lower right of the diagram – called the main sequence stars
H-R Diagram

10. Practice reading the HR Diagram on your worksheet 18-4 “How are Stars Classified?”