1 Explain how knowledge of Stefan-Boltzmann law leads to understanding of temperatures and radii of stars. Summarize the circumstances under which objects produce thermal (continuous), emission line, or absorption line spectra. Explain what is meant by the spectral sequence of stars. Learning Goals....

2 How does the Stefan-Boltzmann law lead to our understanding of temperatures and radii of stars? Summarize the circumstances under which objects produce thermal (continuous), emission line, or absorption line spectra. Explain what is meant by the spectral sequence of stars.

3 Explain how knowledge of Stefan-Boltzmann law leads to understanding of temperatures and radii of stars. Stefan-Boltzmann Law

4 1.Between A and C (large and warm, small and warm), which one will boil water first? 2.Between A and B, which one will boil water first? 3.Between B and D (large and medium, small and hot), which one will boil water first? A B C D Coils of same color have same Temperature A B C D

5 AB C D

6 Applying to stars We have ways of finding L (luminosity).

7 How does the Stefan-Boltzmann law lead to our understanding of temperatures and radii of stars?

8

9 Explain how knowledge of Stefan-Boltzmann law leads to understanding of temperatures and radii of stars. Summarize the circumstances under which objects produce thermal, emission line, or absorption line spectra. Explain what is meant by the spectral sequence of stars.

10 Kirchhoff’s Laws

11 Production of an emission line spectrum Production of a continuous spectrum Illustrating the geometry needed to view each of the kinds of spectra

12 Where is the “cooler, lower-density cloud” in a star? ? Core: 17,000,000 K “Surface”: 6,000 K “Absorption Layer”: 4,000 K

13 Putting filters to practical use:

14 Putting Kirchhoff’s laws to practical use when observing Helix nebula: 1.Absorption 2.Emission 3.Continuous A. White Dwarf B. Diffuse Gas C. Distant star behind cooler gas

15 Summarize the circumstances under which objects produce thermal, emission line, or absorption line spectra.

16 Explain how knowledge of Stefan-Boltzmann law leads to understanding of temperatures and radii of stars. Summarize the circumstances under which objects produce thermal (continuous), emission line, or absorption line spectra. Explain what is meant by the spectral sequence of stars. O B A F G K M L T

17 Universe is full of things that look like stars! Pluto & Charon

18 One of these things is not like the others....

19  Explain what is meant by the spectral sequence of stars

20  Explain what is meant by the spectral sequence of stars

21 Cause for confusion: what about how the spectra looked different because of chemical abundances, such as we learned about in the spectral analysis lab?

 Explain what is meant by the spectral sequence of stars

23  Explain what is meant by the spectral sequence of stars

24 Explain what is meant by the spectral sequence of stars. O B A F G K M L T