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Plasma parameters and geometry of cool and warm active region loops View all abstracts by submitter

Maria Madjarska   Submitted: 2017-05-09 16:57

How the solar corona is heated to high temperatures remains an unsolved mystery in solar physics. In the present study we analyse observations of 50 whole active-region loops taken with the Extreme-ultraviolet Imaging Spectrometer (EIS) on board the Hinode satellite. Eleven loops were classified as cool (<1 MK) and 39 as warm (1-2 MK) loops. We study their plasma parameters such as densities, temperatures, filling factors, non-thermal velocities and Doppler velocities. We combine spectroscopic analysis with linear force-free magnetic-field extrapolation to derive the three-dimensional structure and positioning of the loops, their lengths and heights as well as the magnetic field strength along the loops. We use density-sensitive line pairs from Fe XII, Fe XIII, Si X and Mg VII ions to obtain electron densities by taking special care of intensity background-subtraction. The emission-measure loci method is used to obtain the loop temperatures. We find that the loops are nearly isothermal along the line-of-sight. Their filling factors are between 8% and 89%. We also compare the observed parameters with the theoretical RTV scaling law. We find that most of the loops are in an overpressure state relative to the RTV predictions. In a followup study, we will report a heating model of a parallel-cascade-based mechanism and will compare the model parameters with the loop plasma and structural parameters derived here.

Authors: Haixia Xie, Maria S. Madjarska, Bo Li, Zhenghua Huang, Lidong Xia, Thomas Wiegelmann, Hui Fu, Chaozhou Mou
Projects: Hinode/EIS

Publication Status: ApJ, accepted for publication
Last Modified: 2017-05-10 09:18
Go to main E-Print page  Propagation of Torsional Alfv?n Waves from the Photosphere to the Corona: Reflection, Transmission, and Heating in Expanding Flux Tubes  Explosive chromospheric evaporation driven by nonthermal electrons around one footpoint of a solar flare loop  Edit Entry  Download Preprint  Delete Entry 

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