Magnetic twist: a source and property of space weather

Journal of Space Weather and Space Climate

Dhrubaditya Mitra²  Axel Brandenburg¹  Jörn Warnecke¹ 

[1] Department of Astronomy, AlbaNova University Center, Stockholm University,SE-10691 Stockholm,Sweden;Nordita, AlbaNova University Center,Roslagstullsbacken 23,SE-10691 Stockholm,Sweden

关键词: solar wind;    coronal mass ejection (CME);    solar activity;    turbulence;    MHD;   

Others  :  800684
DOI  :  doi:10.1051/swsc/2012011

 received in 2012-03-05, accepted in 2012-07-10,  发布年份 2012

【 摘 要 】

Aim: We present evidence for finite magnetic helicity density in the heliosphere and numerical models thereof, and relate it to the magnetic field properties of the dynamo in the solar convection zone.

【 授权许可】

   
© Owned by the authors, Published by EDP Sciences 2012

【 图 表 】

Fig. 1.

Fig. 2.

Fig. 3.

Fig. 4.

Fig. 5.

Fig. 7.

Fig. 8.

Fig. 9.

Fig. 2.

Fig. 11.

Fig. 12.

【 参考文献 】

• [1]Blackman, E.G., and A. Brandenburg, Dynamic nonlinearity in large scale dynamos with shear, Astrophys. J., 579, 359–373, 2002. [NASA ADS]
• [2]Blackman, E.G., and A. Brandenburg, Doubly helical coronal ejections from dynamos and their role in sustaining the solar cycle, Astrophys. J., 584, L99–L102, 2003. [NASA ADS]
• [3]Bothmer, V., and R. Schwenn, The structure and origin of magnetic clouds in the solar wind, Ann Geophysicae, 16, 1–24, 1998. [NASA ADS]
• [4]Brandenburg, A., The inverse cascade and nonlinear alpha-effect in simulations of isotropic helical hydromagnetic turbulence, Astrophys. J., 550, 824–840, 2001. [NASA ADS]
• [5]Brandenburg, A., S. Candelaresi, and P. Chatterjee, Small-scale magnetic helicity losses from a mean-field dynamo, MNRAS, 398, 1414–1422, 2009. [NASA ADS]
• [6]Brandenburg, A., K. Subramanian, A. Balogh, and M.L. Goldstein, Scale-dependence of magnetic helicity in the solar wind, Astrophys. J., 734, 9, 2011. [NASA ADS]
• [7]Hubbard, A., and A. Brandenburg, Magnetic helicity fluxes in an α2 dynamo embedded in a halo, Geophys. Astrophys. Fluid Dyn., 104, 577–590, 2010. [NASA ADS]
• [8]Käpylä, P.J., M.J. Korpi, A. Brandenburg, D. Mitra, and R. Tavakol, Convective dynamos in spherical wedge geometry, Astron. Nachr., 331, 73–81, 2010. [NASA ADS]
• [9]Käpylä, P.J., M.J. Mantere, and A. Brandenburg, Cyclic magnetic activity due to turbulent convection in spherical wedge geometry, Astrophys. J. Lett., 755, L22, 2012. [NASA ADS]
• [10]Krause, F., and K.-H. Rädler, Mean-Field Magnetohydrodynamics and Dynamo Theory, Pergamon Press, Oxford, 1980.
• [11]Low, B.C., Solar Activity and the Corona, Sol. Phys., 167, 217–265, 1996. [NASA ADS]
• [12]Low, B.C., Coronal mass ejections, magnetic flux ropes, and solar magnetism, J. Geophys. Res., 106, 25141–25163, 2001. [NASA ADS]
• [13]Matthaeus, W.H., M.L. Goldstein, and C. Smith, Evaluation of magnetic helicity in homogeneous turbulence, Phys. Rev. Lett., 48, 1256–1259, 1982. [NASA ADS]
• [14]Mitra, D., S. Candelaresi, P. Chatterjee, R. Tavakol, and A. Brandenburg, Equatorial magnetic helicity flux in simulations with different gauges, Astron Nachr., 331, 130–135, 2010. [NASA ADS]
• [15]Ortolani, S., and D.D. Schnack, Magnetohydrodynamics of Plasma Relaxation, World Scientific, Singapore, 1993.
• [16]Pouquet, A., U. Frisch, and J. Léorat, Strong MHD helical turbulence and the nonlinear dynamo effect, J. Fluid Mech., 77, 321–354, 1976. [NASA ADS]
• [17]Subramanian, K., and A. Brandenburg, Magnetic helicity density and its flux in weakly inhomogeneous turbulence, Astrophys. J., 648, L71–L74, 2006. [NASA ADS]
• [18]Warnecke, J., and A. Brandenburg, Surface appearance of dynamogenerated large-scale fields, A&A, 523, A19, 2010. [NASA ADS]
• [19]Warnecke, J., A. Brandenburg, and D. Mitra, Dynamo-driven plasmoid ejections above a spherical surface, A&A, 534, A11, 2011. [NASA ADS]
• [20]Warnecke, J., P.J. Käpylä, M.J. Mantere, and A. Brandenburg, Sol. Phys., 2012, in press, arXiv:1112.0505.