High polarization lines of the second solar spectrum of the Solar limb

TL;DR

This paper provides a high-resolution dataset of polarized solar spectra near the limb, revealing polarization levels in various spectral lines, and makes the data publicly available for further research.

Contribution

It introduces a comprehensive, high-resolution dataset of the second solar spectrum with polarization measurements at different solar limb positions.

Findings

Polarization up to 7% in CaI 4227 Å line at the solar limb.

Polarization of 2% in SrI 4607 Å line.

Polarization of 1.4% in BaII 4554 Å line.

Abstract

We present a dataset of high resolution spectra of the Sun of many strongly polarized lines belonging to the second solar spectrum, i.e. the spectrum near the limb in linear polarization (scattering polarization). These solar spectra were obtained in full Stokes polarimetry (I, Q/I, U/I, V/I) in the quiet Sun at various distances from the limb, and at disk centre for comparison, with the ground based CNRS THEMIS telescope. Polarization rates Q/I up to 7% are obtained in CaI 4227 {\AA} line at $\mu$ = cos$\theta$ = 0, while 2% is reached in SrI 4607 {\AA} line and 1.4% in BaII 4554 {\AA}. The spectra shown here are freely available in FITS format to the research community.