Mapping the hidden magnetic field of the quiet Sun

Abstract

The Sun is the only star where we can resolve the intricate magnetism that all convective stars harbor. Yet, more than 99% of its visible surface along the solar cycle (the so-called quiet Sun) is filled with a tangled, unresolved magnetism. These "hidden" fields are thought to store enough magnetic energy to play a role in the heating of the Sun's outer atmosphere, but its field strength is still not constrained. Previous investigations based on the Hanle effect in atomic lines claim a strong magnetization of about 100 G, while the same effect in molecules show a factor of 10 weaker fields. The discrepancy disappears if the magnetic field strength of the hidden is not homogeneous in the solar surface. In this letter, we prove using magnetohydrodynamical simulations that it is possible to infer the average field strength of the hidden quiet Sun magnetic fields using multi-line inversions of intensity profiles in the Zeeman regime. Using this technique with 15 spectral lines in the 1.5 $\mu$m spectral range, we reveal that the spatial distribution of the hidden field is strongly correlated with convection motions, and that the average magnetization is about 46 G. Reconciling our findings with the Hanle ones is not obvious and will require future work on both sides, since it implies an increase of the field strength with height, something that is physically questionable.

arXiv comment9 pages, 5 figures

References in corpus (20)

• A Substantial Amount of Hidden Magnetic Energy in the Quiet Sun
• Inversion of the radiative transfer equation for polarized light
• Spatially coupled inversion of spectro-polarimetric image data I: Method and first results
• Magneto-acoustic waves in sunspots: first results from a new 3D nonlinear magnetohydrodynamic code
• Hidden magnetic fields of young suns
• Strategy for the inversion of Hinode spectropolarimetric measurements in the quiet Sun
• Returning magnetic flux in sunspot penumbrae
• PCA detection and denoising of Zeeman signatures in stellar polarised spectra
• Stray-light contamination and spatial deconvolution of slit-spectrograph observations
• A novel investigation of the small-scale magnetic activity of the quiet Sun via the Hanle effect in the Sr I 4607 Å line
• Numerical simulations of quiet Sun magnetic fields seeded by Biermann battery
• Probing deep photospheric layers of the quiet Sun with high magnetic sensitivity
• Image restoration of solar spectra
• The potential of many-line inversions of photospheric spectropolarimetric data in the visible and near UV
• Evidence for collisional depolarization in the MgH lines of the second solar spectrum
• Solar disk center shows scattering polarization in the Sr I 4607 Å line
• Empirical determination of atomic line parameters of the 1.5 $\mu$m spectral region
• Observations on spatial variations of the Sr~{\sc i} 4607~Å~scattering polarization signals at different limb distances with ZIMPOL
• Detection of spatially structured scattering polarization of Sr I $4607.3$ Å\ with the Fast Solar Polarimeter
• A meta-analysis of the magnetic line broadening in the solar atmosphere

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• DKIST resolves sub-arcsec photospheric scattering polarization
• An iterative OLA method for inversion of solar spectropolarimetric data: I. Single and multiple variable inversions of thermodynamic quantities
• Observational insights into Sr I 4607 Å scattering polarization with DKIST/ViSP