HR: 1340h
AN: SH53A-1251    [Abstracts]
TI: Self-focusing of Shocks and Hydrodynamic Cumulation in the Solar Atmosphere
AU: Tarbell, T
EM: tarbell@lmsal.com
AF: Lockheed Martin Advanced Technology Center, 3251 Hanover Street, Palo Alto, CA 94304 United States
AU: * Ryutova, M
EM: ryutova1@llnl.gov
AF: Lawrence Livermore National Laboratory/IGPP, LLNL/IGPP, L-413, Livermore, CA 94550 United States
AB: Network magnetic field in the solar atmosphere is concentrated in isolated non-collinear thin flux tubes embedded in almost non-magnetic environment with plasma beta β=8π p_ext/B_ext²>> 1. Brought together by convective motions flux tubes collide and reconnect. Post-reconnection dynamics of the photospheric magnetic flux tubes is radically different from a low beta coronal plasma. Here the reconnection does not give in situ heating, but it sets the system in a highly unsteady state. After reconnection, the strongly curved flux tubes behave as elastic bands: straightening they create a sling-shot effect which generates complex 3D shock waves with the curved surface. Self-focusing of these shocks occurs as they propagate upward in the stratified atmosphere, producing a strong cumulative effects. Depending on the geometry of the shock conversion, highly concentrated energy may be either converted entirely into heat or into strong jets, or be distributed between the two. These processes have been observed in simultaneous observations of the solar atmosphere from its surface to the corona obtained with the Solar and Heliospheric Observatory (SOHO) and Transition Region and Coronal Explorer (TRACE) showing a ubiquitous sequence of events that start from cancellation of photospheric magnetic fields, pass through shock formation and result in the transition region supersonic jets and microflares (Ryutova & Tarbell, 2003, Physical Review Letters, 90, 191101). We also find that lateral shocks produced by the reconnection of the same polarity non-collinear magnetic flux tubes may cause the ubiquitous bright points observed in sunspots and their environment. The mechanisms of energy flow and release in the solar atmosphere involve fundamental physical processes that are commonplace throughout astrophysics and laboratory plasma physics. The advances in the coordinated observations with SOHO and TRACE provide a unique opportunity to check the theoretical models, and shed light on the general mechanisms of energy production, transfer and release in stellar atmospheres and other astrophysical objects.
DE: 7509 Corona
DE: 7524 Magnetic fields
DE: 7529 Photosphere
DE: 7836 MHD waves and instabilities (2149, 2752, 6050)
DE: 7851 Shock waves (4455)
SC: SPA-Solar and Heliospheric Physics [SH]
MN: Fall Meeting 2005