Helioseismology

1. Helioseismology 周定一 Dean-Yi Chou 台灣清華大學，物理系 (2010.08, 北京)

2. 1. Solar Oscillations • 2. Global and Local Helioseismology • Probing magnetic fields and flows in the solar convection zone with helioseismology • 4. Solar acoustic energy in magnetic regions • 5. Possible future developments

3. Solar Oscillations Helioseismology (I) 周定一 Dean-Yi Chou 台灣清華大學，物理系 (2010.08, 北京)

4. Helioseismolgy Using solar p-mode oscillations (waves) measured on the solar surface to probe the solar interior.

5. Solar oscillation was discovered by Leighton et al. (1962). • Ulrich & Leibacher (1972?) proposed the p-mode waves. • Deubner (1976?) confirmed p-mode waves with k-ω diagrams.

6. Basic Acoustic Wave Equations

7. Basic Acoustic Wave Equations (cont.) Wave equation

8. Basic Acoustic Wave Equations (cont.) short-wavelength (WKB) approximation dispersion relation pure acoustic wave

9. Mode Analysis dispersion relation

11. angular dependence ( l , m )

12. Radial dependence (p modes)

13. Radial dependence (g modes)

14. Basic Principle to probe Solar Interiors Different modes penetrate into different depths.

15. Observations in Helioseismology Using solar p-mode oscillations (waves) measured on the solar surface to probe the solar interior. Observations setr = R But it still gives the same dispersion relation:

16. k - ω ( l - ν) Diagram

17. Helioseismolgy Instruments Ground-Based Networks • BISON (UK, 1980?): one-pixel, velocity, 7 stations • IRIS (France, 1988): one-pixel, velocity, 7 stations • TON (Taiwan, 1994): 1080 x 1080 intensity image, 4 stations • GONG (USA, 1996): 1024 x 1024 velocity image, 6 stations • LOWL (USA, 1998): 256 x 256 velocity image, 2 stations • SOHO (1996): 192 x 192 & 1024 x 1024, velocity and intensity • Solar B (2006) • SDO (2009) Space

18. Taiwan Oscillation Network (TON)

19. Examples of Important Achievements in Helioseismology • Confirm and refine the standard model • Differential rotation pattern • Wave excitation mechanism • Local helioseismology

20. The End