An Investigation of the Loop Oscillations after a Solar Flare

We study the loop oscillations after a solar flare on 19 January 2023, in the active region N11E40 3196, which is well observed by the SDO/AIA. After tracing the loop position and fitting, we find that the loop oscillations have a period between 3 and 9 min at various locations, such as from the leg to the top or from the inner to the outer loop. Their oscillating amplitudes decrease with time. Two loops display the position oscillation simultaneously with their brightness oscillation. After the analysis of the differential emission measure (DEM), we find that two of their loop position oscillations resulted from the plasma density fluctuation. Meanwhile, it is interesting that the brightness of these two position oscillations displays a typical period of about 4 min, similar to that of the position oscillation. This is possible due to both the plasma density and temperature fluctuation there. Our findings provide the physical clues for studying and understanding the mechanism of the loop position and brightness oscillations.