| 1. |
- Noda, C. Quintero, et al.
(författare)
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Chromospheric polarimetry through multiline observations of the 850-nm spectral region - II. A magnetic flux tube scenario
- 2017
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 472:1, s. 727-737
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Tidskriftsartikel (refereegranskat)abstract
- In this publication, we continue the work started in Quintero Noda et al., examining this time a numerical simulation of a magnetic flux tube concentration. Our goal is to study if the physical phenomena that take place in it, in particular, the magnetic pumping, leaves a specific imprint on the examined spectral lines. We find that the profiles from the interior of the flux tube are periodically doppler shifted following an oscillation pattern that is also reflected in the amplitude of the circular polarization signals. In addition, we analyse the properties of the Stokes profiles at the edges of the flux tube discovering the presence of linear polarization signals for the Ca II lines, although they are weak with an amplitude around 0.5 per cent of the continuum intensity. Finally, we compute the response functions to perturbations in the longitudinal field, and we estimate the field strength using the weak-field approximation. Our results indicate that the height of formation of the spectral lines changes during the magnetic pumping process, which makes the interpretation of the inferred magnetic field strength and its evolution more difficult. These results complement those from previous works, demonstrating the capabilities and limitations of the 850-nm spectrum for chromospheric Zeeman polarimetry in a very dynamic and complex atmosphere.
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| 2. |
- Quintero Noda, C., et al.
(författare)
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Chromospheric polarimetry through multiline observations of the 850nm spectral region III : Chromospheric jets driven by twisted magnetic fields
- 2019
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 486:3, s. 4203-4215
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the diagnostic potential of the spectral lines at 850 nm for understanding the magnetism of the lower atmosphere. For that purpose, we use a newly developed 3D simulation of a chromospheric jet to check the sensitivity of the spectral lines to this phenomenon as well as our ability to infer the atmospheric information through spectropolarimetric inversions of noisy synthetic data. We start comparing the benefits of inverting the entire spectrum at 850 nm versus only the Ca II 8542 angstrom spectral line. We found a better match of the input atmosphere for the former case, mainly at lower heights. However, the results at higher layers were not accurate. After several tests, we determined that we need to weight more the chromospheric lines than the photospheric ones in the computation of the goodness of the fit. The new inversion configuration allows us to obtain better fits and consequently more accurate physical parameters. Therefore, to extract the most from multiline inversions, a proper set of weights needs to be estimated. Besides that, we conclude again that the lines at 850 nm, or a similar arrangement with Ca II 8542 angstrom plus Zeeman-sensitive photospheric lines, pose the best-observing configuration for examining the thermal and magnetic properties of the lower solar atmosphere.
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| 3. |
- Socas-Navarro, H., et al.
(författare)
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An open-source, massively parallel code for non-LTE synthesis and inversion of spectral lines and Zeeman-induced Stokes profiles
- 2015
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 577
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Tidskriftsartikel (refereegranskat)abstract
- With the advent of a new generation of solar telescopes and instrumentation, interpreting chromospheric observations (in particular, spectropolarimetry) requires new, suitable diagnostic tools. This paper describes a new code, NICOLE, that has been designed for Stokes non-LTE radiative transfer, for synthesis and inversion of spectral lines and Zeeman-induced polarization profiles, spanning a wide range of atmospheric heights from the photosphere to the chromosphere. The code features a number of unique features and capabilities and has been built from scratch with a powerful parallelization scheme that makes it suitable for application on massive datasets using large supercomputers. The source code is written entirely in Fortran 90/2003 and complies strictly with the ANSI standards to ensure maximum compatibility and portability. It is being publicly released, with the idea of facilitating future branching by other groups to augment its capabilities.
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