1. Self-organized magnetic structures in computational astrophysics Axel Brandenburg (Nordita/Stockholm) Kemel+12 Ilonidis+11Brandenburg+13Warnecke+11 Käpylä+12

2. Today 2

3. B-class flares? 3

4. Oct2003 4

5. Flights rerouted 5

6. Rerouted 6

7. 7

8. 6 March 8

9. 7 March 9

10. 8 March 10

11. 11 Magnetic fields from the Sun a)Motions from i.Convection instability ii.Magnetorotational inst. iii.Supernova forcing b)Dynamo instability i.Stretch-twist-fold ii.Turbulent dynamo

12. White light 12 Tips of icebergs: Magnetic flux concentrations in magnetogram!

13. 13 Parker’s (1955) dynamo wave Differential rotation (faster inside) Cyclonic convection; Buoyant flux tubes Equatorward migration New loop    - effect

14. Doppler imaging: distant stars 14

15. II Peg: rapidly rotating binary 15 RS CVn type Canum Venaticorum Kochukhov, Mantere, et al (2013) Saar & Brandenburg (1999)

16. Brun, Brown, Browning, Miesch, Toomre 16

17. 17 Cycle now common! Activity from bottom of CZ but at high latitudes Ghizaru, Charbonneau, Racine, …

18. 18 Dynamo wave from simulations Kapyla et al (2012)

19. 19 Dynamo is one example of self-organization

20. 20 Alternative sunspot origins Theories for shallow spots: (i) Collapse by suppression of turbulent heat flux (ii) Negative pressure effects from vs B i B j Kosovichev et al. (2000)

21. 21 Negative effective magnetic pressure instability Gas+turb. press equil. B increases Turb. press. Decreases Net effect?

22. Self-assembly of a magnetic spot Minimalistic model 2 ingredients: –Stratification & turbulence Extensions –Coupled to dynamo –Compete with rotation –Radiation/ionization 22

23. Mean-field models: different scale separation 23 Varying turbulent diffusivity

24. Bi-polar regions, found by accident 24 Warnecke et al. (2013, submitted)

25. Pencil code Started in Sept. 2001 with Wolfgang Dobler High order (6 th order in space, 3 rd order in time) Cache & memory efficient MPI, can run PacxMPI (across countries!) Maintained/developed by ~80 people (SVN) Automatic validation (over night or any time) 0.0013  s/pt/step at 1024 3, 2048 procs http://pencil-code.googlecode.com Isotropic turbulence –MHD, passive scl, CR Stratified layers –Convection, radiation Shearing box –MRI, dust, interstellar –Self-gravity Sphere embedded in box –Fully convective stars –geodynamo Other applications –Chemistry, combustion –Spherical coordinates

26. 26 Increase of revision number User meetings: 2005 Copenhagen 2006 Copenhagen 2007 Stockholm 2008 Leiden 2009 Heidelberg 2010 New York 2011 Toulouse 2012 Helsinki 2013 Lund 2014 Gottingen

27. Pencil h-index 27 Red line gives the diagonal to see the crossing

28. 28 Automatic validation tests

29. 29 Increase in # of auto tests

30. 30 Online data reduction and visualization non-helically forced turbulence

31. Conclusions Turbulence can possess surprising effects –Large scale dynamos –Magnetic flux concentrations Importance for space weather Run-time data evaluation, etc 31