Spectropolarimetry of Atomic and Molecular Lines near 4135nm

TL;DR

This study presents new spectropolarimetric observations of atomic and molecular lines near 4135nm in sunspots, revealing magnetic properties and line splittings that enhance understanding of solar magnetic fields.

Contribution

The paper provides the first spatially scanned spectropolarimetry data near 4135nm and demonstrates the magnetic sensitivity of the Fe I line at 4137nm, which is significantly higher than the 1565nm line.

Findings

Atomic line splittings agree with theoretical calculations.

The Fe I 4137nm line shows large splitting and multiple Stokes V components.

The 4137nm line is a highly sensitive probe of quiet Sun magnetic fields.

Abstract

New spatially scanned spectropolarimetry sunspot observations are made of photospheric atomic and molecular absorption lines near 4135nm. The relative splittings among several atomic lines are measured and shown to agree with values calculated with configuration interaction and intermediate coupling. Large splitting is seen in a line identified with Fe I at 4137nm, showing multiple Stokes V components and an unusual linear polarization. This line will be a sensitive probe of quiet Sun magnetic fields, with a magnetic sensitivity of 2.5 times larger than that of the well-known 1565nm Fe I line.