Solar Physics Division Meeting 2000, June 19-22
Session 2. Corona, Solar Wind, Flares, CMEs, Solar-stellar, Instrumentation, Other
Display, Chair: J. Krall, Monday-Thursday, June 19, 2000, 8:00am-6:00pm, Forum Ballroom

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[2.11] Multi-Thread Modeling of Coronal Loops with TRACE Data

R. W. Nightingale, M. J. Aschwanden, D. Alexander (LMSAL), F. Reale, G. Peres (Univ. Palermo)

The temperature Te(s) and density structure ne(s) of active region loops in EUV observed with TRACE is modeled with a multi-thread model. The model loops are synthesized from the summed emission of many loop threads that have a distribution of maximum temperatures and that satisfy the steady-state Rosner-Tucker-Vaiana (RTV) scaling law, modified by Serio et al. for gravitational stratification (RTVSp). From model-fitting of the 171 and 195 Åfluxes of 41 loops, which have loop half lengths in the range of L=4-320 Mm, we find: (1) The EUV loops can be explained by near-isothermal loop threads in the temperature range of Te ~0.8-1.6 MK with substantially smaller temperature gradients than predicted by the RTVSp model, (2) the loop base pressure, p0 ~0.3±0.1 dyne cm-2, is independent of the loop length L, it agrees with the RTVSp model for the shortest loops, but exceeds the RTVSp model up to a factor of 35 for the largest loops, and (3) the pressure scale height is consistent with hydrostatic equilibrium for the shortest loops, but exceeds the temperature scale height up to a factor of ~3 for the largest loops. This work was supported by the TRACE project at LMSAL (contract NAS5-38099).

Ref.: Aschwanden,M.J., Nightingale,R.W., Alexander,D., Reale,F., and Peres,G. 2000, ApJ, subm., ``Evidence for Nonuniform Heating of Coronal Loops Inferred from Multi-Thread Modeling of TRACE Data'',


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