DKIST resolves sub-arcsec photospheric scattering polarization

Abstract

Scattering polarization signals offer a unique diagnostics of the physical conditions in the solar atmosphere, in particular magnetic fields via the Hanle effect. However, their spatial structure remains poorly constrained due to the difficulty of achieving high spatial resolution and polarimetric sensitivity simultaneously. We present the first direct observation of sub-arcsecond structuring in the linear scattering polarization of the photospheric Sr i 4607 Å\, line near the solar disk center ($\mu$ = 0.74), obtained with the Visible Spectro- Polarimeter (ViSP) at the Daniel K. Inouye Solar Telescope (DKIST). The data achieve about 0".2 resolution with 30 s integration and sufficient sensitivity to detect fine-scale patterns in the total linear polarization, which are evident in Sr i but absent in a nearby Fe i line that is simultaneously observed. Since this Fe i line is more Zeeman-sensitive than the Sr i 4607 Å\, this disparity confirms that the signals in the Sr i 4607 Å\, line arise from scattering. These data provide the first spatially resolved two-dimensional maps of photospheric scattering polarization at sub-arcsecond scales, enabled by the capabilities of a 4-meter solar telescope.

Accepted for publication in Astronomy & Astrophysics, 4 pages and 3 figures

References in corpus (13)

• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• Array Programming with NumPy
• The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
• A Substantial Amount of Hidden Magnetic Energy in the Quiet Sun
• Numerical simulations of quiet Sun magnetism: On the contribution from a small-scale dynamo
• A solar surface dynamo
• The Visible Spectro-Polarimeter of the Daniel K. Inouye Solar Telescope
• Three-dimensional Radiative Transfer Modeling of the Polarization of the Sun's Continuous Spectrum
• The Scattering Polarization of the Sr I 4607 ÅLine at the Diffraction Limit Resolution of a 1-m Telescope
• SPIRITS 16tn in NGC 3556: A heavily obscured and low-luminosity supernova at 8.8 Mpc
• Solar disk center shows scattering polarization in the Sr I 4607 Å line
• Mapping the hidden magnetic field of the quiet Sun
• The impact of limited time resolution on the forward-scattering polarization in the solar Sr I 4607 Å line

Cited by in corpus (1)

• Observational insights into Sr I 4607 Å scattering polarization with DKIST/ViSP