Recovering the Line-Of-Sight Magnetic Field in the Chromosphere from Ca II IR Spectra

TL;DR

This paper introduces a hybrid method combining center-of-gravity and bisector techniques to accurately measure the line-of-sight magnetic field in the solar chromosphere using Ca II IR spectra, validated with simulations and applied to real observations.

Contribution

A novel hybrid technique for deriving chromospheric magnetic fields from Ca II IR spectra, integrating established methods for improved accuracy.

Findings

Validated with magneto-static simulations of flux tubes.

Successfully applied to IBIS observations at Dunn Solar Telescope.

Revealed chromospheric magnetic structures linked to photospheric flux.

Abstract

We propose a method to derive the line-of-sight magnetic flux density from measurements in the chromospheric Ca II IR line at 854.2 nm. The method combines two well-understood techniques, the center-of-gravity and bisector methods, in a single hybrid technique. The technique is tested with magneto-static simulations of a flux tube. We apply the method to observations with the Interferometric Bidimensional Spectrometer (IBIS) installed at the Dunn Solar Telescope of the NSO/SP to investigate the morphology of the lower chromosphere, with focus on the chromospheric counterparts to the underlying photospheric magnetic flux elements.