Characterization of intensity and spatial variations along coronal loops

II. A TRACE case study

Instituto de Astronomía y Física del Espacio, CONICET, Argentina e-mail: costa@iafe.uba.ar

Received: 1 November 2004
Accepted: 30 May 2005

Abstract

We describe dynamical features and evolutionary characteristics of brightening coronal loops. We describe intensity variations, both in space and time, along a coarse grain loop structure, confirming high speed velocity scenarios. We apply the method to TRACE space-born images that show a compound of several magnetic threads. MICA ground-based images display a unique non-resolved loop structure. We confirm that a coherent behavior of the intensity along neighboring magnetic tubes occurs, i.e. we obtain a similar pattern from both telescopes: each has two branches, suggesting the sliding down of plasma in both directions from a given position on the loop structure. The apparent sliding down occurs in approximately 12 min. After the first appearance, TRACE registers two reiterations of the phenomenon suggesting a wave-based explanation. The feasibility of wave-based and flow-based models is analyzed. In either case, in order to explain the coherent coronal behavior the scenario of apparently non-interacting coronal threads requires theoretical explanations that consider uniform chromospheric conditions covering the footpoints of all the related magnetic tubes. We suggest a characteristic longitude of coherence.