Examination of Magnetic Helicity and Plasma Oscillation Periods in the Active Region NOAA12353 Prior to Three C-Class Flares.

This work aims to investigate the long-period oscillations of NOAA12353 prior to a series of C-class flares and to correlate the findings with the 3-5 minute oscillations that were previously studied in the same active region. The objective of this work is to elucidate the presence of various oscillations with long periods in the lower solar atmosphere both before and after the flare events. Understanding the relationship between oscillations in solar active regions and their solar eruption activity is essential. To detect long-period oscillations the emergence, shearing, and total magnetic helicity flux components were assessed from the photosphere to the top of the chromosphere. To analyse the magnetic helicity flux in the lower solar atmosphere, linear force-free field extrapolation was used to construct a model of the magnetic field structure of the active region. Subsequently, the location of long-period oscillations in the active region was probed by examining the spectral energy density of the measured intensity signal in the 1700Å, 1600Å, and 304Å channels of the Atmospheric Imaging Assembly (AIA) of the Solar Dynamics Observatory (SDO). Significant periods of oscillations were determined by means of wavelet analysis. Based on the evolution of the three magnetic helicity flux components, 3-8 hour periods were found both before and after the flare events, spanning from the photosphere to the chromosphere. These 3-8 hour periods were also evident throughout the active region in the photosphere in the 1700Å channel. Observations of AIA 1600Å and 304Å channels, which cover the chromosphere to the transition region, revealed oscillations lasting 3-8 hours near the region where the flare occurred. The spatial distribution of the measured long-period oscillations mirror the previously reported distribution of 3-5 minute oscillations in NOAA12353, seen both before and after the flares. This case study suggest that varying oscillation properties in a solar active region could be indicative of future flaring activity.