2D non-LTE modelling of a filament observed in the Hα line with the DST/IBIS spectropolarimeter
Authors:
P. Schwartz, S. Gunar, J. M. Jenkins, D.M. Long, P. Heinzel, D. P. Choudhary
Image & caption:
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Image caption::
Map of the integrated intensities in the H_alpha line core with marked six positions located along the observed filament fragment. Profiles from these six positions were used in the filament plasma diagnostics by means of the modelling. By each of the six positions, results of the modelling are listed.
Description:
We studied a fragment of large quiescent filament observed on 29 May 2017 in the H_alpha spectral line by the Interferometric BIdimensional Spectropolarimeter (IBIS) mounted on the Dunn Solar Telescope. The filament was in the state of activation and it erupted approximately 24 hours later. We used model of filament based on radiative transfer in hydrogen plasma in the two-dimensional geometry calculated under departure from the local thermodynamical equilibrium. Synthetic profiles of H_alpha calculated by the model were compared with the observed ones for diagnostics of the filament plasma. Results of the modelling showed that while one part of the filament is cooler, denser and more dynamic (temperatures from 6000 K to 10000 K, densities between 3E-13 g/cm^3 and 8×E-13 g/cm^3 and line-of-sight velocities oriented in direction to the observer of 6-7 km/s), its other part is hotter, less dense (temperatures from 11000 to 14000 K and densities around 1E-13 g/cm^3) and almost without any dynamics. These results indicate that filaments are activated non-uniformly before their eruptions.
Reference:
Astronomy & Astrophysics 631, article No. A146, pp. 1-12.
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