Analysis of the Temperature and Emission Measure of Solar Coronal Arcades and Test of a Scaling Law of Flare/Arcade Loop Length
Abstract
We analyze 17 arcades to study the relations between solar flares and arcades. Soft X-ray images taken with Yohkoh's soft X-ray telescope are used to derive T0, EM0, and temporal variation of Tarc and EMarc, where Tarc and T0 are the temperatures of an arcade and prearcade region and EMarc and EM0 are the volume emission measures of an arcade and prearcade region. It is found that T0~2 MK and Tarc~4 MK. We also estimate prearcade coronal electron density n0 and arcade electron density narc to find that narc is comparable to n0 (narc~n0~108 cm-3). Using these observed EM, T, and n0, we calculate the theoretical loop length Ltheor based on the scaling law for solar and stellar flares derived by Shibata & Yokoyama and compare it with observed flare/arcade loop length Lobs. The result shows a good correlation between them (Ltheor~Lobs) and indicates the need of plasma β for the scaling law (Ltheor~EM3/5T-8/5n- 2/50β-6/5). This supports the theory of the scaling law and is indirect evidence that flares and arcades are heated by the same magnetic reconnection mechanism.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- November 2002
- DOI:
- 10.1086/345076
- Bibcode:
- 2002ApJ...579L..45Y
- Keywords:
-
- Sun: Corona;
- Sun: Flares;
- Sun: X-Rays;
- Gamma Rays