The Elementary Structure of Coronal Loops
Abstract
There is the question whether the plasma of coronal loops consists of unresolved strands or not, given the best spatial resolution of <1" we have today with EUV telescopes such as TRACE. Since the hypothetical loop strands would be thermally insulated from each other, due to the inhibited cross-field diffusion in the coronal plasma that has a plasma-beta parameter significantly smaller than unity, we expect that loop strands have arbitrarily different heating rates and temperatures. Consequently, both resolved as well as unresolved loop strands are expected not to be co-spatial in different temperature filters. We present the results of a triple-filter analysis of a larger number of coronal loop structures observed with TRACE in the 171, 195, and 284 A filters, where we measure the cospatiality of loop substructures with sub-arcsecond accuracy in near-simultaneous measurements with triple filters. In virtually all loop structures we identify multiple resolved substructures that are not cospatial in triple temperature filters, but are cospatial in dual temperature filters and consistent with a single temperatures over partial loop length segments. From these results we conclude that the cross-section of heated loop strands is resolved on ~1" spatial scale, but no thermal equilibrium is achieved over the entire length of coronal loops, and thus loops are always asymmetric in their temperature and density structure.
- Publication:
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AGU Spring Meeting Abstracts
- Pub Date:
- May 2005
- Bibcode:
- 2005AGUSMSP13B..02A
- Keywords:
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- 7509 Corona