Abstract

One big puzzle in Solar Physics is why coronal loops tracing the magnetic field lines are observed in EUV emission? In other words, what is the thermodynamic evolution of coronal loops? To tackle this issue, we use a 1D hydrodynamic model describing a loop as an amalgamation of strands evolving independently. The energy input is prescribed by the Parker model of nanoflare heating: discrete distribution of short bursts releasing energy (about 10^24 erg) along the loop. We first show that the model can reproduce the main observed features, especially focusing on the ubiquitous existence of blue-shifts in spectral observations. The modelled Doppler-shifts are a consequence of condensation at the foot-points of the loop inducing cool plasma moving downwards, and of evaporation generating outflows of hot material. The second step is to study the cooling of a previously heated loop, and to answer the following questions: what is the characteristic time-scale of cooling? what are the signatures of cooling in different pass-bands?