1. Characteristics of Stars

2. Star Definition
Star – A body of gases consisting mainly of hydrogen and helium that gives off a tremendous amount of energy (electromagnetic radiation)

3. Star Color – Depends upon surface temperature
Blue stars – above 30,000 C
White stars – 8, ,000 C
Yellow stars – about 5,550 C (sun)
Orange stars – about 4,000 C
Red stars – about C

4. Star Color

5. Star Size
Vary from dwarf stars (size of the earth) to super giants that are 1000 times bigger than sun

6. Star sizes

7. Brightness of stars (magnitude)
Absolute Magnitude – true brightness of a star – Depends upon temperature and size Apparent magnitude – brightness of a star as viewed from earth. Depends upon temperature, size, and distance to earth

8. Absolute magnitude

9. Classification of Stars – Hertzsprung-Russell (H-R) diagram – Comparison of absolute magnitude and temperature of stars.
Main Sequence -most common star – (sun)
Red Giants - very large, cool bright star
Supergiants - extremely large bright star
White dwarf – small, hot, dim star

10. H-R Diagram