HR: 1330h
AN: SH13C-08    [Abstracts]
TI: Dynamics of the Magnetic Network on the Sun
AU: * Hasan, S
EM: hasan@vsnl.com
AF: Indian Institute of Astrophysics, Koramangala, Bangalore, 560034 India
AU: van Ballegoiijen, A
EM: vanballe@cfa.harvard.edu
AF: Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 United States
AU: Kalkofen, W
EM: wolf@cfa.harvard.edu
AF: Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 United States
AU: Steiner, O
EM: steiner@smtp.kis.uni-freiburg.de
AF: Kiepenheuer Institut fur Sonnenphysik, Schoneckstr. 6, Freiburg, 7800 Germany
AB: Observations have revealed the presence of a rich spectrum of waves with different periods in regions of the solar atmosphere called the "magnetic network" that are dominated by strong magnetic fields. This network is believed to be heated by dissipation of magnetohydrodynamic (MHD) waves, but the MHD processes involved in wave generation, propagation and dissipation are poorly understood. In this work we attempt to identify some of the processes that occur in the network and which contribute to its dynamics and heating. We model the network as consisting of individual magnetic elements or flux tubes, rooted in intergranular lanes, with a typical horizontal size of 100 km. They expand upward and merge with their neighbors at a height of about 600 km. Above this height the magnetic field becomes uniform. An equilibrium configuration based on the above model is constructed by solving the magnetostatic equations in 2-D. Waves are generated in this medium by means of motions at the lower boundary. We focus on transverse driving which generates fast waves within the flux tubes and acoustic waves at the interface of the tubes and the field-free medium, but not otherwise in the field-free gas. The acoustic waves at the interface are due to compression of the gas on one side of the flux tube and expansion on the other. These waves travel upward along the two sides of the (2D) flux tube and enter it, where they become longitudinal waves. For impulsive excitation with a time constant of 120 s, we find that a dominant feature is the creation of vortical motions that propagate upwards. We have identified a new and efficient mechanism for the generation of longitudinal waves and shock formation in the chromosphere. We examine the observational implications of our results and their broad applications to chromospheric heating and activity.
DE: 7507 Chromosphere
DE: 7524 Magnetic fields
DE: 7529 Photosphere
SC: SPA-Solar and Heliospheric Physics [SH]
MN: 2005 Joint Assembly