Models for solar magnetic loops. III. Dynamic models and coronal diagnostic spectrometer observations

In the present work SOHO Coronal Diagnostic Spectrometer (CDS) observations of a quiescent active region loop are compared to a steady state, dynamic loop model. Three different heating functions are adopted: uniform, concentrated at the top, and concentrated at the footpoints. Predicted temperature and density profiles of the selected loop are compared with those obtained from CDS observations using line ratios and an emission measure analysis. The latter method also allows us to measure the loop filling factor. The space of parameters of the model is investigated in an effort to achieve agreement with observations. The effects of uncertainties and of CDS instrumental limitations on the results are assessed. We find that no agreement can be found between model predictions and observations. Possible causes of the disagreement and areas of further investigation are discussed. This work also demonstrates the potential of high-resolution spectroscopy in loop studies, even in the presence of moderate spatial resolution.