Association of mid-infrared solar plages with Calcium K line emissions and magnetic structures

TL;DR

This study demonstrates that mid-infrared solar observations can effectively identify plage structures associated with magnetic activity and calcium line emissions, revealing thermal and magnetic correlations in active regions.

Contribution

It introduces a new optical setup for mid-IR solar imaging and establishes the spatial association between mid-IR plages, calcium K line emissions, and magnetic structures.

Findings

Mid-IR plages are about 140 K hotter than surrounding regions.

Mid-IR bright plages closely match CaII K1v line plages.

Mid-IR observations correlate with magnetic field structures.

Abstract

Solar mid-IR observations in the 8-15 micrometer band continuum with moderate angular resolution (18 arcseconds) reveal the presence of bright structures surrounding sunspots. These plage-like features present good association with calcium CaII K1v plages and active region magnetograms. We describe a new optical setup with reflecting mirrors to produce solar images on the focal plane array of uncooled bolometers of a commercial camera preceded by germanium optics. First observations of a sunspot on September 11, 2006 show a mid-IR continuum plage exhibiting spatial distribution closely associated with CaII K1v line plage and magnetogram structures. The mid-IR continuum bright plage is about 140 K hotter than the neighboring photospheric regions, consistent with hot plasma confined by the magnetic spatial structures in and above the active region