| Issue |
A&A
Volume 673, May 2023
|
|
|---|---|---|
| Article Number | A19 | |
| Number of page(s) | 12 | |
| Section | The Sun and the Heliosphere | |
| DOI | https://doi.org/10.1051/0004-6361/202245612 | |
| Published online | 26 April 2023 | |
The IAG spectral atlas of the spatially resolved Sun: Centre-to-limb observations⋆
Institut für Astrophysik und Geophysik, Georg-August Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
e-mail: momo.ellwarth@uni-goettingen.de
Received:
2
December
2022
Accepted:
2
March
2023
Context. Solar surface magneto-convection appears as granulation pattern that impacts spectral lines in terms of both shape and wavelength. Such induced effects also tend to vary over the observed solar disc because of the changing observation angle and, thus, the changing observation height as well. Centre-to-limb observations of the resolved Sun offer an insight into the variable spectral behaviour across different heliocentric observing positions, providing crucial information about limb darkening, convective velocities, and line profile variability relevant to radial velocity (RV) calculations. Thus, RV measurements and exoplanet transit spectroscopy depend on precise reference templates.
Aims. We want to provide a spectroscopic centre-to-limb solar atlas at high spectral resolution and high-frequency accuracy. The atlas shall help improve the understanding of the solar atmosphere and convection processes.
Methods. We performed high-resolution observations of the resolved quiet Sun with a Fourier transform spectrograph at the Institut für Astrophysik und Geophysik in Göttingen. Our dataset contains a wavelength range from 4200 Å to 8000 Å. We obtained 165 spectra in total, with a spectral resolution of Δν = 0.024 cm−1, corresponding to a resolving power R of 700 000 at ∼6000 Å.
Results. We present a centre-to-limb solar atlas containing 14 heliocentric positions. To check for consistency, we investigated the Fe I 6175 Å absorption line and compared our line profiles with previous centre-to-limb observations and also with simulations. The line profile and also the bisector profiles are generally consistent with previous observations, but we have identified differences to model line profiles, especially close to the solar limb.
Key words: methods: observational / standards / line: profiles / techniques: spectroscopic
Data and electronic version of atlas are available at https://www.astro.physik.uni-goettingen.de/research/solar-lib and at the CDS via anonymous ftp to cdsarc.cds.unistra.fr (130.79.128.5) or via https://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/673/A19
© The Authors 2023
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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