1. Coronal Mass Ejections - the exhaust of modern dynamos Examples: systematic swirl (helicity) Measuring it quantitatively Connection with the dynamo Axel Brandenburg (Nordita, Stockholm)

2. 2 Examples of helical exhaust

3. 3 Sigmoidal structures: North/South dependence south

4. 4 Sigmoidal filaments (from S. Gibson)

5. 5

6. 6 Magnetic helicity

7. 7 Flux crossings J. Chae (2000, ApJ) + + ++- -

8. 8 It’s a popular logo too…

9. 9 Magnetic helicity from crossings J. Chae (2000, ApJ) ++- -

10. 10 Current helicity and magn. hel. Flux Bao & Zhang (1998), neg. in north, plus in south (also Seehafer 1990) Berger & Ruzmaikin (2000) S N DeVore (2000) (for BR & CME)

11. 11 Helicity in Magnetic Clouds From fits to a linear force-free field Lynch et al. (2005)

12. 12 Helicity from time series Matthaeus et al. (1982)

13. 13

14. 14 Nindos et al. (2003)

15. 15 Nindos & Andrews (2004)

16. 16 Magnetic helicity conservation How J diverges as   0 Ideal limit and ideal case similar!

17. 17 No helicity production by flows but segragation in space: H<0 H>0 Generates toroidal from poloidal field Poloidal field regenerated by tilting (Coriolis force)

18. 18 Twisting an existing tube: segragation in spectral space

19. 19 Cancelling magn helicity introduced in single tube  

20. 20  -effect dynamos (large scale) Differential rotation (prehelioseism: faster inside) Cyclonic convection; Buoyant flux tubes Equatorward migration New loop    - effect ?need meridional circulation

21. 21 Tilt  pol. field regeneration N-shaped (north) S-shaped (south) standard dynamo picture  internal twist as dynamo feedback

22. 22 Production of LS helicity forcing produces and Yousef & Brandenburg A&A 407, 7 (2003) But no net helicity production therefore:  alpha effect

23. 23 Problems with  -effect Catastrophic quenching?? –  ~ R m -1,  t ~ R m -1 –Field strength vanishingly small!?! Something wrong with simulations –so let’s ignore the problem Possible reasons: –Suppression of lagrangian chaos? –Suffocation from small scale magnetic helicity?

24. 24 Connection with  effect: writhe with internal twist as by-product  clockwise tilt (right handed)  left handed internal twist both for thermal/magnetic buoyancy  effect produces helical field

25. 25 Simulations: forced turbulence w/shear Negative current helicity: net production in northern hemisphere 10 46 Mx 2 /cycle Brandenburg & Sandin (2004, A&A 427, 13) Helicity fluxes from shear: Vishniac & Cho (2001, ApJ 550, 752) Subramanian & Brandenburg (2004, PRL 93, 20500)

26. 26 Saturation: 50% energy in large scales geometry here relevant to the sun no helicity, e.g. azimuthally averaged neg helicity (northern hem.) Rogachevskii & Kleeorin (2003, 2004)

27. 27 Conclusion 11 yr cycle Dyamo (SS vs LS) Problems –  -quenching – slow saturation Solution –Modern  -effect theory –j.b contribution –Magnetic helicity fluxes Location of dynamo –Distrubtion, shaped by –near-surface shear 10 46 Mx 2 /cycle