| Presentation Title: | Investigation of Quasi-periodic pulsations (QPPs) in solar flares |
| Author(s): | Sargam Mulay, Lyndsay Fletcher, Rahul Sharma |
Abstract:
Solar flares are explosive energetic events that produce radiative signatures at all layers of the solar atmosphere. Quasi-periodic pulsations (QPPs) are the most commonly observed phenomena in solar flares exhibiting periodic fluctuations in the observed radiation. Our research aims to carry out a systematic investigation of quasi-periodic pulsations in M7.3 class solar flare ribbons and study their height-wise distribution using various low and high-temperature UV spectral lines observed by the Interface Region Imaging Spectrograph (IRIS). The time series analysis of GOES soft X-rays and RHESSI hard X-rays revealed multiple conspicuous oscillatory patterns during the impulsive phase of the flare. At the same time, the IRIS UV spectral images showed sawtooth pattern intensity fluctuations in space as the ribbon sweeps the slit with time. Small-scale substructures at various locations within the ribbon are tracked in Slit-Jaw images and the time series analysis showed the oscillatory patterns with characteristic periods. The non-linear and non-stationary properties of QPPs observed along the flare ribbons in various time series were studied thoroughly using the Empirical Mode Decomposition (EMD) and the results confirmed the existence of multi-periodic regimes. Combining data from various observatories facilitated us to study the role of QPPs in flare energy release at various heights in the solar atmosphere and study their relationship with the plasma properties such as Doppler and Non-thermal velocities obtained for the stationary and moving components of spectral lines.