Analysis of spatially deconvolved polar faculae

TL;DR

This study investigates the magnetic and thermal properties of solar polar faculae by analyzing their vertical stratification using Hinode/SP data, revealing their hot plasma nature and magnetic field orientation.

Contribution

It provides new insights into the magnetic and thermal structure of polar faculae through detailed inversions and analysis of their stratification at different heights.

Findings

Polar faculae consist of hot plasma with low line of sight velocities.

Magnetic fields in polar faculae are nearly perpendicular to the solar surface.

Magnetic field locations are slightly shifted towards the disc centre due to the hot wall effect.

Abstract

Polar faculae are bright features that can be detected in solar limb observations and they are related to magnetic field concentrations. Although there is a large number of works studying them, some questions about their nature as their magnetic properties at different heights are still open. Thus, we aim to improve the understanding of solar polar faculae. In that sense, we infer the vertical stratification of the temperature, gas pressure, line of sight velocity and magnetic field vector of polar faculae regions. We performed inversions of the Stokes profiles observed with Hinode/SP after removing the stray light contamination produced by the spatial point spread function of the telescope. Moreover, after solving the azimuth ambiguity, we transform the magnetic field vector to local solar coordinates. The obtained results reveal that the polar faculae are constituted by hot plasma with low line of sight velocities and single polarity magnetic fields in the kilogauss range that are nearly perpendicular to the solar surface. We also found that the spatial location of these magnetic fields is slightly shifted respect to the continuum observations towards the disc centre. We believe that this is due to the hot wall effect that allows detecting photons that come from deeper layers located closer to the solar limb.