HR: 1340h
AN: SH13A-0275    [Abstracts]
TI: Solar Arcades as Possible Minimum Dissipative Relaxed States
AU: Bhattacharya, R
EM: ramitendranath.bhattacharya@saha.ac.in
AF: Saha Institute of Nuclear Physics, I/AF Bidhannagar, Calcutta, W.B 700064 India
AU: Janaki, M S
EM: ms.janaki@saha.ac.in
AF: Saha Institute of Nuclear Physics, I/AF Bidhannagar, Calcutta, W.B 700064 India
AU: * Dasgupta, B
EM: dasgupta@ucr.edu
AF: Institute of Geophysics and Planetary Physics, University of California at Riverside, Riverside, CA 92521 United States
AU: Zank, G P
EM: zank@ucr.edu
AF: Institute of Geophysics and Planetary Physics, University of California at Riverside, Riverside, CA 92521 United States
AB: Arcade-type magnetic field structures originating from the photosphere are relevant to the understanding of different types of solar prominences, coronal loops and coronal heating. In most of the existing literature, these loop-like magnetic structures are modelled as force-free fields (FFF) without any plasma flow. The system is assumed to be isolated and non-dissipative. In reality the photospheric plasma hardly qualifies to be isolated in nature and the existence of an external drive in the form of a dynamo field is always possible. Solar prominences are not ideal either since dissipative effects are believed to play a major role in coronal heating. The above observations indicate that a force-free model based on a non-dissipative plasma may not be a suitable candidate to replicate the arcade structures and further investigations are required. In our work, we have proposed the arcade structures as minimum dissipative relaxed states (including both the viscous and resistive channels) pertaining to a two-fluid description of the plasma. The obtained relaxed state is non force-free in nature and appropriate to an open system with external drives. The Euler-Lagrange equations are solved in Cartesian coordinates subject to the existing photospheric boundary conditions. The solutions are seen to support flow-containing arcade like magnetic field configurations with inherent dissipative properties that may play an important role in the coronal heating. An interesting feature observed is the generation of different types of arcades with the variation of a single parameter characterizing the relaxed state. Also, recent observations with the LASCO coronagraph on board the SOHO spacecraft suggest that the helmet streamers originating from the sun may have an internal triple-arcade structure. The two-fluid relaxed state obtained here is also seen to support such structures.
DE: 7509 Corona
DE: 7524 Magnetic fields
DE: 7531 Prominence eruptions
SC: SPA-Solar and Heliospheric Physics [SH]
MN: Fall Meeting 2005