1. SUN COURSE - SLIDE SHOW 7
Today: waves

2. (i) Waves in penumbra of sunspot
Waves on Sun - 4 exs
(i) Waves in penumbra of sunspot

3. Image enhanced

4. (ii) Wave from Flare
In photosphere (MDI)
(8-100 km/s
70 mins)

5. (iii) ? Structure of Solar Interior
Guitar string can oscillate in different normal modes
Sun too
Recently SOHO discovered several million !!
3D Schematic

6. Different modes

7. Sound waves - trapped in convection zone -reflected at top/
refracted at bottom
i.e., wave turns !!

8. Wave paths

9. SOHO MDI - Line of sight velocity

10. Close-up

11. SOHO -- MDI Deduces frequencies:
Measures velocity of Sun's surface at million pts/min
Deduces frequencies:
Deduced T(r) -- agrees with model to < 1%

12. Power spectrum from MDI
Variation of sound speed
with depth.

13. --> Sun’s Internal Rotation Rate
At surface:
* Faster at equator --
Expect:
* const. on cylinders
* B generated throughout conv. zone
Surprise:
-- const on radial lines
-- intense shear layer ? site dynamo

14. The Sun’s Internal Rotation Rate
Angular velocity constant on radial lines
in the convection zone.
Radiative interior in solid body rotation.
Thin layer of strong radial shear at the base of the convection zone – tachocline.

15. See below sunspot by t-distance seismology
Wave speed slower - cooler
Wave speed higher - B

17. (iv) Possibly Important for Heating Corona to few MK
2 mechanisms:
Reconnection or Waves
Originally suggested sound waves - >
generate by turbulence - propagate up - shocks
But - not observed
- magnetic regions hotter
?? Magnetic waves

18. From TRACE discovered waves after eruption

19. Wave initiated by a flare

20. Numerical experiment

21. (v) Chromosphere/T.R are not static plane layers !
MHD Simulation
Corona
t. region
Chromor
Photor light/
dense.
Chromosphere pervaded by waves
Mode conversions where Cs=Ca

22. That’s why we have developed a theory forSo
That’s why we have developed a theory for
Magnetic Waves
? Waves heat atmosphere
Not corona -- amplitude of waves much too low
Chromosphere ?? --
wave power factor 10 too small (Fossum & Carlsson, 2005)
But wave theory important for new field of “Coronal Seismology”
-- deduce properties of corona