Slow Magneto-acoustic Waves Observed above Quiet-Sun Region in a Dark Cavity

TL;DR

This study reports the detection of slow magneto-acoustic waves with unusually short periods (~50 s) in a dark cavity above a quiet-Sun region, expanding understanding of wave phenomena in the solar corona.

Contribution

It presents the first observation of short-period slow MA waves in a quiet-Sun cavity, differing from typical longer-period waves seen in active regions.

Findings

Detected slow MA wave trains with ~50 s period.

Wave properties similar to known slow MA waves, except for shorter period.

Waves observed in a dark cavity above quiet-Sun region.

Abstract

Waves play a crucial role in diagnosing the plasma properties of various structures in the solar corona and coronal heating. Slow magneto-acoustic (MA) waves are one of the important magnetohydrodynamic waves. In past decades, numerous slow MA waves were detected above the active regions and coronal holes, but rarely found elsewhere. Here, we investigate a `tornado'-like structure consisting of quasi-periodic streaks within a dark cavity at about 40--110 Mm above the quiet-Sun region on 2011 September 25. Our analysis reveals that these streaks are actually slow MA wave trains. The properties of these wave trains, including the phase speed, compression ratio, kinetic energy density, etc., are similar to those of the reported slow MA waves, except that the period of these waves is about 50 s, much shorter than the typical reported values (3--5 minutes).