Stationary quasi-periodic pulsations in 20-second cadence TESS flares

Context. Quasi-periodic pulsations (QPPs) are an inherent feature of solar and stellar flares. However, the mechanism behind them is debated hence it is necessary to further study them to obtain a complete picture of flares and their contribution to coronal heating. Aims. We analyze 20-second cadence TESS light curves from sectors 27 to 80 to detect stellar flares and QPPs. Methods. Stellar flare detection was carried out using an automated detection routine based on autoregressive integrated moving average models. QPPs were detected using a Fourier model comparison test (AFINO). Results. We detected 3878 flares across 1285 flaring stars. Notably, 61.2% of flares had a duration of less than 10 min. 61 QPPs were detected across 57 stars significantly expanding the current stellar QPP catalog. The detected periods of the QPPs were in the range of 42 to 193 seconds. In the diagram showing QPP periods against the flare duration a branch emerges. It shows a positive correlation with the flare duration, meaning longer duration flares host longer period QPPs. Conclusion. Our study detected short-period and sub-minute QPPs in stellar flares that have rarely been explored in other works. We find similar scaling laws between solar and stellar QPPs which indicates that QPPs in stellar flares might be analogous to the ones in solar flares as both show evidence of scaling with flare duration.