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

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 Å, as well as ten of the most commonly observed spectral lines at the SST (Ca II H & K, H$\beta$, Mg I 5173 Å, C I 5380 Å, Fe I 6173 Å, Fe I 6301 Å, H$\alpha$, O I 7772 Å, and Ca II 8542 Å). 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.

Published in A&A. CLV data is available in the CDS

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Cited by in corpus (13)

• A comparative study of two X2.2 and X9.3 solar flares observed with HARPS-N: Reconciling Sun-as-a-star spectroscopy and high-spatial resolution solar observations in the context of the solar-stellar connection
• Solar oxygen abundance using SST/CRISP center-to-limb observations of the O I 7772 Å line
• Combined analysis of stellar and planetary absorption lines via global forward-transit simulations
• Convective characteristics of Fe I lines across the solar disc
• Comparison of chromospheric diagnostics in a 3D model atmosphere: H$\alpha$ linewidth and mm continua
• On the center-to-limb variations of the He I 10 830 Å triplet
• Variations of the Ca II K Line Profile Parameters with Solar Latitude and Time Observed from Kodaikanal Solar Observatory
• Automatic detection of Ellerman bombs in the H$\alpha$ line
• The calm before the storm: High spatial resolution mosaic of active region NOAA 14274 at the onset of an X1.2 flare
• High-spectral Resolution, Multi-wavelength Center-to-limb Observations of the Sun
• Solar Flux Atlases: The new HARPS-N Quiet Sun Benchmark and Ca II H & K Lines Continuum Normalisation
• EMISSA: Exploring millimetre indicators of solar-stellar activity III. Comparison of Ca II indices and millimetre continua in a 3D model atmosphere
• An Hα Transit of HD 189733b to Assess Stellar Activity Across the Transit Chord Close to JWST Observations