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arXiv · 2212.03991

Center-to-limb variation of spectral lines and continua observed with SST/CRISP and SST/CHROMIS

A. G. M. Pietrow·D. Kiselman·O. Andriienko·D. J. M. Petit dit de la Roche·C. J. Díaz Baso·F. Calvo
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Abstract

Observations of center-to-limb variations (CLV) of spectral lines and continua provide a good test for the accuracy of models of solar and stellar atmospheric structure and spectral-line formation. They are also widely used to constrain elemental abundances and are becoming increasingly important in atmospheric studies of exoplanets. However, only a few such data sets exist for chromospheric lines. We aim to create a set of standard profiles by means of mosaics made with the CRISP and CHROMIS instruments of the Swedish 1-m Solar Telescope (SST), as well as to explore the robustness of said profiles obtained using this method. For each spectral line we use a mosaic that ranges from the center to the limb. Each of these mosaics are averaged down to 50 individual spectral profiles, spaced by 0.02 in the $\mu$ scale. These profiles are corrected for p-mode oscillations, and their line parameters (equivalent width, line shift, full-width at half-maximum, and line depth) are then compared against literature values where possible. We present a set of 50 average profiles that are spaced equidistantly along the cosine of the heliocentric angle ($\mu$) by steps of 0.02 for five continuum points between 4001 and 7772 \AA, as well as ten of the most commonly observed spectral lines at the SST (Ca II H & K, H$\beta$, Mg I 5173 \AA, C I 5380 \AA, Fe I 6173 \AA, Fe I 6301 \AA, H$\alpha$, O I 7772 \AA, and Ca II 8542 \AA). Center-to-limb variation of line profiles and continua are shared in the CDS as machine-readable tables; providing a quantitative constraint on theoretical models that aim to model stellar atmospheres.

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A. G. M. Pietrow, D. Kiselman, O. Andriienko, D. J. M. Petit dit de la Roche, C. J. Díaz Baso, F. Calvo. 2022-12-07. Center-to-limb variation of spectral lines and continua observed with SST/CRISP and SST/CHROMIS. https://doi.org/10.1051/0004-6361%2F202244811

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