Astrophysics and Space Sciences Transactions www.astrophys-space-sci-trans.net 1810-6528 1810-6536 3 1 2007 10.5194/astra-3-29-2007 http://www.astrophys-space-sci-trans.net/3/29/2007/ http://www.astrophys-space-sci-trans.net/3/29/2007/astra-3-29-2007.html http://www.astrophys-space-sci-trans.net/3/29/2007/astra-3-29-2007.pdf 29 33 2007-12-04 MHD simulation of electric currents in the solar atmosphere caused by photospheric plasma motion J. C. Santos J. Büchner Max-Planck Institute for Solar System Research, Katlenburg-Lindau, Germany Photospheric plasma motion may cause the build-up of electric currents in the solar atmosphere. These electric currents may then dissipate and heat the corona, cause EUV and X-ray Bright Points (BPs) and trigger flares. In this work we use a 'data driven' 3D MHD model to study the generation of electric currents in the solar atmosphere by photospheric plasma motion. The model was applied to photospheric measurements below an observed EUV-BP. The observed photospheric magnetic field and the derived horizontal plasma motion were used as initial and boundary conditions of a simulation. The horizontal motion gave rise to electric currents in the chromosphere, transition region and lower corona. The currents formed in the area where the motion was applied and above the main concentrations of the photospheric magnetic field. Alfvén, H.: Granulation, magneto-Hydrodynamic waves and the heating of the solar corona, Mon. Not. Roy. Astron. Soc., 107, 211–219, 1947. Büchner, J.: Locating current sheets in the solar corona, Space Sci. Rev., 122, 149–160, 2006. Büchner, J. and Daughton, W.: Reconnection of Magnetic Fields: Magnetohydrodynamics, Collisionless Theory and Observations, edited by J. Birn and E. R. Priest, Cambridge: Cambridge University Press, 144-153, 2007. Büchner, J. and Elkina, N.: Vlasov code simulation of anomalous resistivity, Space Sci. Rev., 121, 237–252, 2005. Büchner, J. and Elkina, N.: Anomalous resistivity of current-driven isothermal plasmas due to phase space structuring, Phys. Plasmas, 13, 2304–2313, 2006. Büchner, J., Nikutowski, B., and Otto, A.: Magnetic coupling of photosphere and corona: MHD simulation for multi-wavelenght observations, in Multi-Wavelength Investigations of Solar Activity, Proc. IAU Symp., 223, 353–356, 2004. Büchner, J., Nikutowski, B., and Otto, A.: Coronal heating by\vadjust transition region reconnection, Proc. SOHO 15 Workshop, Coronal Heating, St. Andrews, Scotland, 6–9 September 2004, ESA SP-575, 2004. Büchner, J., Nikutowski, B., and Otto, A.: Plasma acceleration due to transition region reconnection, Particle acceleration in astrophysical plasmas: Geospace and beyond, edited by D. Gallagher, AGU monograph, Washington, 161–170, 2005. Démoulin, P. and Berger, M. A.: Magnetic energy and helicity fluxes at the photospheric level, Solar Physics, 215, 203–215, 2003. Longcope, D W.: A model for current sheets and reconnection in x-ray bright points, Astrophys. J., 507, 433–442, 1998. Madjarska, M S., Doyle, J G., Teriaca, L., and Banerjee, D.: An EUV bright point as seen by SUMER, CDS, MDI and EIT on-board SoHO, Astron. Astrophys., 398, 775–784, 2003. November, L J. and Simon, G W.: Precise proper-motion measurement of solar granulation, Astrophys. J., 333, 427–442, 1988. Otto,~A., Büchner, J., and Nikutowski, B.: Force-free magnetic field extrapolation for MHD boundary conditions in simulations of the solar atmosphere, Astron. Astrophys., 468, 313–321, 2007. Parker, E N.: Topological dissipation and the small-scale fields in turbulent gases, Astrophys. J., 174, 499–510, 1972. Parnell, C E., Priest, E R, and Titov, V S.: A model for x-ray bright points due to unequal cancelling flux sources, Solar Physics, 153, 217–235, 1994. Priest, E R., Parnell, C E., and Martin, S F.: A converging flux model of an x-ray bright point and an associated canceling magnetic feature, Astrophys. J., 427, 459–474, 1994. von Rekowski, B., Parnell, C E., and Priest, E R.: Solar coronal heating by magnetic cancellation - II. Disconnected and unequal bipoles, Mon. Not. Roy. Astron. Soc., 369, 43–56, 2006. Roussev, I., Galsgaard, K., and Judge, P G.: Physical consequences of the inclusion of anomalous resistivity in the dynamics of 2D magnetic reconnection, Astron. Astrophys., 382, 639–649, 2002. Seehafer, N.: Determination of constant α force-free solar magnetic fields from magnetograph data, Solar Physics, 58, 215–223, 1978.