Automatic detection technique for solar filament oscillations in GONG data

TL;DR

This paper presents an automated spectral technique using FFT to detect and analyze solar filament oscillations in GONG H-alpha data, demonstrating reliability and agreement with previous methods.

Contribution

The work introduces a novel automated method for detecting filament oscillations in solar data, improving efficiency and reliability over manual or less systematic approaches.

Findings

Method successfully detects oscillations consistent with previous studies.

The technique identifies oscillations in filaments with high confidence.

Automated detection can be applied to large datasets for solar cycle studies.

Abstract

Solar filament oscillations have been known for decades. Now thanks to the new capabilities of the new telescopes, these periodic motions are routinely observed. Oscillations in filaments show key aspects of their structure. A systematic study of filament oscillations over the solar cycle can shed light on the evolution of the prominences. This work is a proof of concept that aims to automatically detect and parameterise such oscillations using H$\alpha$ data from the GONG network of telescopes. The proposed technique studies the periodic fluctuations of every pixel of the H$\alpha$ data cubes. Using the FFT we compute the power spectral density (PSD). We define a criterion to consider whether it is a real oscillation or whether it is a spurious fluctuation. This consists in considering that the peak in the PSD must be greater than several times the background noise with a confidence level of 95\%. The background noise is well fitted to a combination of red and white noise. We applied the method to several observations already reported in the literature to determine its reliability. We also applied the method to a test case, which is a data set in which the oscillations of the filaments were not known a priori. The method shows that there are areas in the filaments with PSD above the threshold value. The periodicities obtained are in general agreement with the values obtained by other methods. In the test case, the method detects oscillations in several filaments. We conclude that the proposed spectral technique is a powerful tool to automatically detect oscillations in prominences using H$\alpha$ data.