A solar active region loop compared with a 2D MHD model

¹ Research Center of Astronomy and Applied Mathematics, Academy of Athens, Soranou Efessiou 4, 115 27, Athens, Greece e-mail: [cgontik;edara]@cc.uoa.gr
² IASA and Section of Astrophysics, Astronomy and Mechanics, Department of Physics, University of Athens, Panepistimiopolis, 157 84, Athens, Greece e-mail: gpetrie@hao.ucar.edu;tsingan@phys.uoa.gr

Received: 10 May 2004
Accepted: 5 January 2005

Abstract

We analyzed a coronal loop observed with the Normal Incidence Spectrometer (NIS), which is part of the Coronal Diagnostic Spectrometer (CDS) on board the Solar and Heliospheric Observatory (SOHO). The measured Doppler shifts and proper motions along the selected loop strongly indicate unidirectional flows. Analysing the Emission Measure Curves of the observed spectral lines, we estimated that the temperature along the loop was about 380 000 K. We adapted a solution of the ideal MHD steady equations to our set of measurements. The derived energy balance along the loop, as well as the advantages/disadvantages of this MHD model for understanding the characteristics of solar coronal loops are discussed.