Temperature and density structure of hot and cool loops derived from the analysis of trace data

Abstract

We address the plasma structuring both across and along the magnetic field in two sets of solar coronal loops, observed with TRACE in the 17lÅ and 195Å passbands. We derive, after proper background removal, the density stratification and the thermal structure of the plasma in the fibrils forming the loops with two techniques: a) filter ratio diagnostic (195 Å/171 Å) and b) modeling intensity profiles along the fibrils with hydrostatic models. We find evidence of a hot fibril (T ∼ 5·106 K), with temperature and density stratification well-described with a typical non-isothermal hydrostatic loop model, and evidence of rather cold fibrils (T ∼ 2 · 105 K), isothermal and probably in dynamic conditions.