1. The HR diagram

2. First, let’s look at temperature on the bottom of the diagram.

3. Temp increases from right to left
The HR Diagram
hot
(blue)
cool
(red)
Temp increases from right to left

4. Next, let’s look at luminosity on the left of the diagram.
Remember…luminosity compares the brightness of stars to the brightness of our sun.

5. Luminosity increases from bottom to top
The HR Diagram
bright
Luminosity increases from bottom to top
dim

6. Now, let’s find our sun on the HR Diagram.

7. The HR Diagram
Our Sun

8. Our sun is an average star in the main sequence stage of its life cycle.

9. The HR Diagram Hottest and brightest Main Sequence Stars Our Sun
Coolest and dimmest

10. As stars move through their life cycle, their temperature changes causing them to move around the HR Diagram.

11. Very bright; not that hot; large in size
The HR Diagram
Supergiants
Very bright; not that hot; large in size
Our Sun

12. Less bright; similar temp to supergiants; smaller in size
The HR Diagram
Red Giants
Less bright; similar temp to supergiants; smaller in size
Our Sun

13. The HR Diagram
Our Sun
White Dwarfs
Very hot; dim; small

14. Last, but not least, let’s color our HR Diagram to match the temperature.

15. The HR Diagram