2D non-LTE modelling of a filament observed in the H_alpha line with the DST/IBIS spectropolarimeter. (arXiv:1910.03607v1 [astro-ph.SR])

2D non-LTE modelling of a filament observed in the H_alpha line with the DST/IBIS spectropolarimeter. (arXiv:1910.03607v1 [astro-ph.SR])
<a href="http://arxiv.org/find/astro-ph/1/au:+Schwartz_P/0/1/0/all/0/1">P. Schwartz</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Gunar_S/0/1/0/all/0/1">S. Gunar</a> (2), <a href="http://arxiv.org/find/astro-ph/1/au:+Jenkins_J/0/1/0/all/0/1">J. M. Jenkins</a> (3), <a href="http://arxiv.org/find/astro-ph/1/au:+Long_D/0/1/0/all/0/1">D. M. Long</a> (3), <a href="http://arxiv.org/find/astro-ph/1/au:+Heinzel_P/0/1/0/all/0/1">P. Heinzel</a> (2), <a href="http://arxiv.org/find/astro-ph/1/au:+Choudhary_D/0/1/0/all/0/1">D. P. Choudhary</a> (4) ((1) Astronomical Institute of Slovak Academy of Sciences, Slovak Republic, (2) Astronomical Institute, The Czech Academy of Sciences, Czech Republic, (3) UCL-Mullard Space Science Laboratory, Holmbury St. Mary, Surrey, UK, (4) Department of Physics &amp; Astronomy, California State University, CA, USA)

We study a fragment of a large quiescent filament observed on May 29, 2017 by
the Interferometric BIdimensional Spectropolarimeter (IBIS) mounted at the Dunn
Solar Telescope. We focus on its quiescent stage prior to its eruption. We
analyse the spectral observations obtained in the H$alpha$ line to derive the
thermodynamic properties of the plasma of the observed fragment of the
filament. We used a 2D filament model employing radiative transfer computations
under conditions that depart from the local thermodynamic equilibrium. We
employed a forward modelling technique in which we used the 2D model to
producesynthetic H_alpha line profiles that we compared with the observations.
We then found the set of model input parameters, which produces synthetic
spectra with the best agreement with observations. Our analysis shows that one
part of the observed fragment of the filament is cooler, denser, and more
dynamic than its other part that is hotter, less dense, and more quiescent. The
derived temperatures in the first part range from 6,000 K to 10,000$ K and in
the latter part from 11,000 K to 14,000 K. The gas pressure is 0.2-0.4
dyn/cm}^{2} in the first part and around 0.15 dyn/cm}^{2} in the latter part.
The more dynamic nature of the first part is characterised by the line-of-sight
velocities with absolute values of 6-7 km/s and microturbulent velocities of
8-9 km/s. On the other hand, the latter part exhibits line-of-sight velocities
with absolute values 0-2.5 km/s and microturbulent velocities of 4-6 km/s.

We study a fragment of a large quiescent filament observed on May 29, 2017 by
the Interferometric BIdimensional Spectropolarimeter (IBIS) mounted at the Dunn
Solar Telescope. We focus on its quiescent stage prior to its eruption. We
analyse the spectral observations obtained in the H$alpha$ line to derive the
thermodynamic properties of the plasma of the observed fragment of the
filament. We used a 2D filament model employing radiative transfer computations
under conditions that depart from the local thermodynamic equilibrium. We
employed a forward modelling technique in which we used the 2D model to
producesynthetic H_alpha line profiles that we compared with the observations.
We then found the set of model input parameters, which produces synthetic
spectra with the best agreement with observations. Our analysis shows that one
part of the observed fragment of the filament is cooler, denser, and more
dynamic than its other part that is hotter, less dense, and more quiescent. The
derived temperatures in the first part range from 6,000 K to 10,000$ K and in
the latter part from 11,000 K to 14,000 K. The gas pressure is 0.2-0.4
dyn/cm}^{2} in the first part and around 0.15 dyn/cm}^{2} in the latter part.
The more dynamic nature of the first part is characterised by the line-of-sight
velocities with absolute values of 6-7 km/s and microturbulent velocities of
8-9 km/s. On the other hand, the latter part exhibits line-of-sight velocities
with absolute values 0-2.5 km/s and microturbulent velocities of 4-6 km/s.

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