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  The potential of many-line inversions of photospheric spectropolarimetric data in the visible and near UV

Riethmüller, T., & Solanki, S. K. (2019). The potential of many-line inversions of photospheric spectropolarimetric data in the visible and near UV. Astronomy and Astrophysics, 622: A36. doi:10.1051/0004-6361/201833379.

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Riethmüller, Tino1, Author           
Solanki, Sami K.1, 2, Author           
1Department Sun and Heliosphere, Max Planck Institute for Solar System Research, Max Planck Society, ou_1832289              
2ERC Advanced Grant: Solar magnetic field and its influence on solar variability and activity (SOLMAG), Max Planck Institute for Solar System Research, Max Planck Society, ou_3164813              


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 Abstract: Our knowledge of the lower solar atmosphere is mainly obtained from spectropolarimetric observations, which are often carried out in the red or infrared spectral range and almost always cover only a single or a few spectral lines. Here we compare the quality of Stokes inversions of only a few spectral lines with many-line inversions. In connection with this, we have also investigated the feasibility of spectropolarimetry in the short-wavelength range, 3000 Å−4300 Å, where the line density but also the photon noise are considerably higher than in the red, so that many-line inversions could be particularly attractive in that wavelength range. This is also timely because this wavelength range will be the focus of a new spectropolarimeter in the third science flight of the balloon-borne solar observatory SUNRISE. For an ensemble of state-of-the-art magneto-hydrodynamical atmospheres we synthesize exemplarily spectral regions around 3140 Å (containing 371 identified spectral lines), around 4080 Å (328 lines), and around 6302 Å (110 lines). The spectral coverage is chosen such that at a spectral resolving power of 150 000 the spectra can be recorded by a 2K × 2K detector. The synthetic Stokes profiles are degraded with a typical photon noise and afterward inverted. The atmospheric parameters of the inversion of noisy profiles are compared with the inversion of noise-free spectra. We find that significantly more information can be obtained from many-line inversions than from a traditionally used inversion of only a few spectral lines. We further find that information on the upper photosphere can be significantly more reliably obtained at short wavelengths. In the mid and lower photosphere, the many-line approach at 4080 Å provides equally good results as the many-line approach at 6302 Å for the magnetic field strength and the line-of-sight (LOS) velocity, while the temperature determination is even more precise by a factor of three. We conclude from our results that many-line spectropolarimetry should be the preferred option in the future, and in particular at short wavelengths it offers a high potential in solar physics.


Language(s): eng - English
 Dates: 2019-01-302019
 Publication Status: Published in print
 Pages: -
 Publishing info: -
 Table of Contents: -
 Rev. Type: Peer
 Identifiers: DOI: 10.1051/0004-6361/201833379
 Degree: -



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Project information

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Project name : ERC-2015-AdG - SOLMAG
Grant ID : 695075
Funding program : Horizon 2020 (H2020)
Funding organization : European Commission (EC)

Source 1

Title: Astronomy and Astrophysics
  Other : Astron. Astrophys.
Source Genre: Journal
Publ. Info: Berlin : Springer-Verlag
Pages: - Volume / Issue: 622 Sequence Number: A36 Start / End Page: - Identifier: ISSN: 0004-6361
CoNE: https://pure.mpg.de/cone/journals/resource/954922828219_1