1. A Practical Introduction to Stellar Nonradial Oscillations (i) Rich Townsend University of Delaware ESO Chile ̶ November 2006 TexPoint fonts used in EMF. Read the TexPoint manual before you delete this box.: A AAA

2. Overview Historical Perspective –Radial pulsators –Nonradial pulsators Waves in stars Global oscillations Surface variations Rotation effects Driving mechanisms

3. p-mode Surface Variations

4. g-mode Surface Variations

5. p modes vs. g modes

6. Carnot Cycle

7. Excitation Mechanisms Add heat when temperature is high Remove heat when temperature is low Mechanisms: –κ : opacity –ε : nuclear energy –δ : superadiabatic stratification –γ : ionization

8. OPAL / OP Opacities

9. 5 M ¯ model

10. WN model

11. Brown Dwarf model

12. Asteroseismology Compare observations against models –Frequencies –Multi-color light curve Amplitudes Phases –Spectroscopy Line-profile variations Mean profiles

13. Frequencies

14. Photometric Amplitudes ℓ = 1 ℓ = 2 ℓ = 3

15. Line-Profile Variations

16. lpv: Time-Series

17. Modeling Photometric –Semi-analytical Spectroscopic –Semi-analytical Moments TVS –Numerical BRUCE/KYLIE PULSTAR

18. Photometric Modeling Stamford & Watson (1981) Semi-analytical formula for flux changes

19. Photometry of SPB stars

20. Spectroscopic Modeling Represent stellar surface with mesh Perturb mesh with pulsation(s) Rasterize mesh Synthesize spectra for each pixel Combine spectra

25. Spectral Synthesis For each pixel: –Teff –log g –V –  Interpolate spectrum in intensity grid

30. Pulsation & Rotation Coriolis force becomes significant when Ω/ω > 0.5 Pulsation confined within equatorial waveguide New formula –Townsend (2003) –Extends Dziembowski (1977) –Low-frequency (SPBs)

31. Effects of Rotation Townsend (2003)