What can we learn from classifying stars? In the second and third activities, you looked at two ways that astronomers classify stars: by the strength of their hydrogen lines and by their temperatures. Let’s compare these two ways to see how they are related.
Explore 6. Look back to the tables you created in Explore exercises 3, 4, 5, and 6. In the first row of the table below, list the stars (1-7) in order of decreasing Hα line strength (strongest on the left, weakest on the right.) In the second row, list the stars in order of decreasing temperature (hottest on the left, coolest on the right).
| Strongest Hα Line | Weakest Hα Line | |||||||
| Hottest Temperature | Coolest Temperature |
Are these two classification schemes the same?
Explore 7. Now, look back at the classification scheme you created for stars in Explore 2, with the letters A through O. Using the star numbers you wrote in Explore 6 as a guide, fill in the table below using the classes A through O rather than the star numbers.
| Strongest Hα Line | Weakest Hα Line | |||||||
| Hottest Temperature | Coolest Temperature |
Did you write the same letters in the same order in the two rows? Are these two classification schemes the same?
On the next page, you will answer questions about this classification scheme, to see what it can tell you about stars.