1. Hertzsprung - Russell Diagram
Luminosity vs Temperature

2. Hertzsprung -Russell Diagram
HR diagram
Shows the relationship between absolute magnitude and temperature of stars
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3. In general…
As brightness decreases, so does temperature

4. 3 distinct areas of the HR diagram
Main Sequence Stars
Giants
Dwarfs

5. Main Sequence Stars 90% of stars are main sequence stars
Hot = Bright = Big
Cool = Dim = Small
Sun is average

6. Some are not main sequence stars
Giant
Dwarfs

7. Red Giants
Giants are brighter and more massive than main sequence stars of the same temperature

8. Betelgeuse in Orion

9. Arcturus in Bootes

10. Antares in Scorpius

11. White Dwarfs
Smaller and dimmer than main sequence stars of the same temperature