Spatial variations of the Sr I 4607 ˚A scattering polarization signals at subgranular scale observed with ZIMPOL at the GREGOR telescope

Dhara, Sajal Kumar and Capozzi, Emilia and Gisler, Daniel and Bianda, Michele and Ramelli, Renzo and Berdyugina, Svetlana and Alsina, Ernest and Belluzzi, Luca (2019) Spatial variations of the Sr I 4607 ˚A scattering polarization signals at subgranular scale observed with ZIMPOL at the GREGOR telescope. Il nuovo cimento C, 42 (1). pp. 1-4. ISSN 1826-9885

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Abstract

Sr I 4607 ˚A spectral line shows one of the strongest scattering polarization signals in the visible solar spectrum. The amplitudes of these signals are expected to vary at granular spatial scales. This variation can be due to changes in the magnetic field intensity and orientation (Hanle effect) as well as due to spatial and temporal variations in the plasma properties. Measuring the spatial variation of such polarization signal are challenging since both high spatial resolution and high spectropolarimetric sensitivity are required at the same time. To the aim of measuring these spatial variations at granular scale, we carried out a spectropolarimetric measurement with the Zurich IMaging POLarimeter (ZIMPOL), at the GREGOR solar telescope at different limb distances on solar disk. Our results show a spatial variation of scattering linear polarization signals in Sr I 4607 ˚A line at the granular scale at every μ, starting from 0.2 to 0.8. The correlation between the scattering linear polarization signal amplitude and the continuum intensity imply statistically that the scattering polarization is higher at the granular regions than in the intergranular lanes.

Item Type: Article
Subjects: 500 Scienze naturali e Matematica > 530 Fisica
Depositing User: Marina Spanti
Date Deposited: 27 Nov 2020 09:48
Last Modified: 27 Nov 2020 09:48
URI: http://eprints.bice.rm.cnr.it/id/eprint/20369

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