Quasi-periodic pulsations in solar and stellar flares: an overview of recent results

TL;DR

This review summarizes recent observational and modeling advances in understanding quasi-periodic pulsations (QPPs) in solar and stellar flares, highlighting their prevalence, multiple periods, and unresolved mechanisms.

Contribution

It provides an updated overview of QPP observations, modeling efforts, and the current challenges in identifying their triggering mechanisms in both solar and stellar contexts.

Findings

QPPs are an inherent feature of nearly all solar flares.

Multiple periods are commonly observed in QPPs.

High-quality Kepler data enables systematic study of stellar QPPs.

Abstract

Quasi-periodic pulsations (or QPPs) are periodic intensity variations in the flare emission, across all wavelength bands. In this paper, we review the observational and modelling achievements since the previous review on this topic by Nakariakov & Melnikov (2009). In recent years, it has become clear that QPPs are an inherent feature of solar flares, because almost all flares exhibit QPPs. Moreover, it is now firmly established that QPPs often show multiple periods. We also review possible mechanisms for generating QPPs. Up to now, it has not been possible to conclusively identify the triggering mechanism or cause of QPPs. The lack of this identification currently hampers possible seismological inferences of flare plasma parameters. QPPs in stellar flares have been detected for a long time, and the high quality data of the Kepler mission allows to study the QPP more systematically. However, it has not been conclusively shown whether the time scales of stellar QPPs are different or the same as those in solar flares.