1. Lecture 14…What spectroscopy tells us about the nature of the stars
The Solar Spectrum
A beautiful example of Kirchoff’s Laws

3. But first, an illustration of how m (apparent magnitude), M (absolute magnitude) , and the relation to distance can tell us something interesting in astronomy: Cepheid variables

4. The prototype….Delta Cephei
Iota (3.52)
delta
Epsilon (4.19) Zeta (3.35) Lambda(5.04)

5. The Importance of Cepheids…the Period-Luminosity Relation

6. Starlight…application of spectroscopy to stars
Continuous spectrum gives surface temperature (Wien’s Law)
Spectral lines give chemical composition, temperature (also), speed of rotation (How?) and other properties
Examples of stellar spectra…what can we say?

7. Spectral classes of stars: O,B,A,F,G,K,M
What can you say about the temperatures of these stars?

8. With information provided by spectroscopy, we can search for correlations between stellar properties

9. What the data show: the Hertzsprung-Russell Diagram
Highest quality data from the Hipparchus spacecraft

10. The Hertzsprung-Russell Diagram and the Types of Stars
See Figure 16.20
Types of stars, important terms
Main Sequence
Giants
Supergiants
White dwarfs
What does it all mean?

11. Hertzsprung-Russell Diagram