Fitting peculiar spectral profiles in He I 10830 Aa absorption features

The new generation of solar instruments provides better spectral, spatial, and temporal resolution for a better understanding of the physical processes that take place on the Sun. Multiple-component profiles are more commonly observed with these instruments. Particularly, the Hei 10830 Aa triplet pr...

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Bibliographic Details
Published in:Astronomische Nachrichten 2016-11, Vol.337 (10), p.1057-1063
Main Authors: Manrique, Gonzalez, Kuckein, C, Pastor Yabar, A, Collados, M, Denker, C, Fischer, CE, Gomory, P, Diercke, A, Bello Gonzalez, N, Schlichenmaier, R, Balthasar, H, Berkefeld, T, Feller, A, Hoch, S, Hofmann, A, Kneer, F, Lagg, A, Nicklas, H, Orozco Suarez, D, Schmidt, D, Schmidt, W, Sigwarth, M, Sobotka, M, Solanki, S K, Soltau, D, Staude, J, Strassmeier, K G, Verma, M, Volkmer, R, von der Luehe, O, Waldmann, T
Format: Article
Language:English
Subjects:
Atmospherics
Doppler effect
Fine structure
Fittings
Inversions
Spectra
Spectrographs
Temporal resolution
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Summary:The new generation of solar instruments provides better spectral, spatial, and temporal resolution for a better understanding of the physical processes that take place on the Sun. Multiple-component profiles are more commonly observed with these instruments. Particularly, the Hei 10830 Aa triplet presents such peculiar spectral profiles, which give information on the velocity and magnetic fine structure of the upper chromosphere. The purpose of this investigation is to describe a technique to efficiently fit the two blended components of the Hei 10830 Aa triplet, which are commonly observed when two atmospheric components are located within the same resolution element. The observations used in this study were taken on 2015 April 17 with the very fast spectroscopic mode of the GREGOR Infrared Spectrograph (GRIS) attached to the 1.5-m GREGOR solar telescope, located at the Observatorio del Teide, Tenerife, Spain. We apply a double-Lorentzian fitting technique using Levenberg-Marquardt least-squares minimization. This technique is very simple and much faster than inversion codes. Line-of-sight Doppler velocities can be inferred for a whole map of pixels within just a few minutes. Our results show sub- and supersonic downflow velocities of up to 32km s super(-1) for the fast component in the vicinity of footpoints of filamentary structures. The slow component presents velocities close to rest. ( copyright 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
ISSN:0004-6337
1521-3994
DOI:10.1002/asna.201512433