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arXiv · 1105.2157

Observations of the forward scattering Hanle effect in the Ca i 4227 {\AA} line

M. Bianda·R. Ramelli·L. S. Anusha·J. O. Stenflo·K. N. Nagendra·R. Holzreuter·M. Sampoorna·H. Frisch·H. N. Smitha
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Abstract

Chromospheric magnetic fields are notoriously diffcult to measure. The chromospheric lines are broad, while the fields are producing a minuscule Zeeman-effect polarization. A promising diagnostic alternative is provided by the forward-scattering Hanle effect, which can be recorded in chromospheric lines such as the He i 10830 {\AA} and the Ca i 4227 {\AA} lines. We present a set of spectropolarimetric observations of the full Stokes vector obtained near the center of the solar disk in the Ca i 4227 {\AA} line with the ZIMPOL polarimeter at the IRSOL observatory.We detect a number of interesting forward-scattering Hanle effect signatures, which we model successfully using polarized radiative transfer. Here we focus on the observational aspects, while a separate companion paper deals with the theoretical modeling.

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M. Bianda, R. Ramelli, L. S. Anusha, J. O. Stenflo, K. N. Nagendra, R. Holzreuter, M. Sampoorna, H. Frisch, H. N. Smitha. 2011-05-11. Observations of the forward scattering Hanle effect in the Ca i 4227 {\AA} line. https://doi.org/10.1051/0004-6361/201117047

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