THE EFFECT OF ISOTOPIC SPLITTING ON THE BISECTOR AND INVERSIONS OF THE SOLAR Ca II 854.2 nm LINE

Leenaarts, Jorrit; Carlsson, Mats; Kochukhov, Oleg

doi:10.1088/2041-8205/784/1/L17

Title: THE EFFECT OF ISOTOPIC SPLITTING ON THE BISECTOR AND INVERSIONS OF THE SOLAR Ca II 854.2 nm LINE

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Abstract

The Ca II 854.2 nm spectral line is a common diagnostic of the solar chromosphere. The average line profile shows an asymmetric core, and its bisector shows a characteristic inverse-C shape. The line actually consists of six components with slightly different wavelengths depending on the isotope of calcium. This isotopic splitting of the line has been taken into account in studies of non-solar stars, but never for the Sun. We performed non-LTE radiative transfer computations from three models of the solar atmosphere and show that the line-core asymmetry and inverse C-shape of the bisector of the 854.2 nm line can be explained by isotopic splitting. We confirm this finding by analyzing observations and showing that the line asymmetry is present irrespective of conditions in the solar atmosphere. Finally, we show that inversions based on the Ca II 854.2 nm line should take the isotopic splitting into account, otherwise the inferred atmospheres will contain erroneous velocity gradients and temperatures.

Authors:

Leenaarts, Jorrit; Carlsson, Mats ^[1]; Kochukhov, Oleg ^[2]

Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029 Blindern, N-0315 Oslo (Norway)
Department of Physics and Astronomy, Uppsala University, Box 516, SE-75120 Uppsala (Sweden)

Publication Date:: Thu Mar 20 00:00:00 EDT 2014

OSTI Identifier:: 22365959

Resource Type:: Journal Article

Journal Name:: Astrophysical Journal Letters

Additional Journal Information:: Journal Volume: 784; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 2041-8205

Country of Publication:: United States

Language:: English

Subject:: 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASYMMETRY; CALCIUM IONS; CALCULATION METHODS; CHROMOSPHERE; LTE; RADIANT HEAT TRANSFER; STAR MODELS; SUN; VELOCITY; WAVELENGTHS

Citation Formats


                    Leenaarts, Jorrit, Carlsson, Mats, De la Cruz Rodríguez, Jaime, and Kochukhov, Oleg. THE EFFECT OF ISOTOPIC SPLITTING ON THE BISECTOR AND INVERSIONS OF THE SOLAR Ca II 854.2 nm LINE.  United States: N. p., 2014. 
        Web.  doi:10.1088/2041-8205/784/1/L17.

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                    Leenaarts, Jorrit, Carlsson, Mats, De la Cruz Rodríguez, Jaime, & Kochukhov, Oleg. THE EFFECT OF ISOTOPIC SPLITTING ON THE BISECTOR AND INVERSIONS OF THE SOLAR Ca II 854.2 nm LINE.  United States.  https://doi.org/10.1088/2041-8205/784/1/L17

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                    Leenaarts, Jorrit, Carlsson, Mats, De la Cruz Rodríguez, Jaime, and Kochukhov, Oleg. 2014.  
        "THE EFFECT OF ISOTOPIC SPLITTING ON THE BISECTOR AND INVERSIONS OF THE SOLAR Ca II 854.2 nm LINE".  United States.  https://doi.org/10.1088/2041-8205/784/1/L17.

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@article{osti_22365959,

  title        = {THE EFFECT OF ISOTOPIC SPLITTING ON THE BISECTOR AND INVERSIONS OF THE SOLAR Ca II 854.2 nm LINE},

  author       = {Leenaarts, Jorrit and Carlsson, Mats and De la Cruz Rodríguez, Jaime and Kochukhov, Oleg},

  abstractNote = {The Ca II 854.2 nm spectral line is a common diagnostic of the solar chromosphere. The average line profile shows an asymmetric core, and its bisector shows a characteristic inverse-C shape. The line actually consists of six components with slightly different wavelengths depending on the isotope of calcium. This isotopic splitting of the line has been taken into account in studies of non-solar stars, but never for the Sun. We performed non-LTE radiative transfer computations from three models of the solar atmosphere and show that the line-core asymmetry and inverse C-shape of the bisector of the 854.2 nm line can be explained by isotopic splitting. We confirm this finding by analyzing observations and showing that the line asymmetry is present irrespective of conditions in the solar atmosphere. Finally, we show that inversions based on the Ca II 854.2 nm line should take the isotopic splitting into account, otherwise the inferred atmospheres will contain erroneous velocity gradients and temperatures.},

  doi          = {10.1088/2041-8205/784/1/L17},

  url          = {https://www.osti.gov/biblio/22365959},
  journal      = {Astrophysical Journal Letters},

  issn         = {2041-8205},

  number       = 1,

  volume       = 784,

  place        = {United States},

  year         = {Thu Mar 20 00:00:00 EDT 2014},

  month        = {Thu Mar 20 00:00:00 EDT 2014}

}

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