Three-minute wave enhancement in the solar photosphere

TL;DR

This paper demonstrates that three-minute oscillations are present in the solar photosphere and their amplitude varies with magnetic field strength, providing insights into wave behavior in magnetic regions.

Contribution

It shows that three-minute waves exist at the formation height of the Fe I 617.3 nm line and are confined to magnetic umbral regions, revealing new details about wave-magnetic field interactions.

Findings

Three-minute waves are present at the line formation height.

Wave amplitude depends on magnetic field strength.

Waves are confined within the umbral region.

Abstract

It is a well-known result that the power of five-minute oscillations is progressively reduced by magnetic fields in the solar photosphere. Many authors have pointed out that this fact could be due to a complex interaction of many processes: opacity effects, MHD mode conversion and intrinsic reduced acoustic emissivity in strong magnetic fields. While five-minute oscillations are the dominant component in the photosphere, it has been shown that chromospheric heights are in turn dominated by three-minute oscillations. Two main theories have been proposed to explain their presence based upon resonance filtering in the atmospheric cavity and non linear interactions. In this work we show, through the analysis of IBIS observations of a solar pore in the photospheric Fe I 617.3 nm line, that three-minute waves are already present at the height of formation of this line and that their amplitude depends on the magnetic field strength and is strictly confined in the umbral region.