Formation and enhancement of coronal rain induced by a large-scale coronal wave

Coronal waves and coronal rain are important dynamic phenomena in the solar corona. They play a crucial role in understanding the energy transfer and plasma evolution processes in the solar atmosphere. However, the detailed formation process of coronal rain and its connection to perturbations such as coronal waves, as well as the dynamic and thermodynamic characteristics of coronal loops during this process, still need further observational verification and analysis. This study aims to explore the physical mechanism of coronal rain formation induced by coronal waves, clarify their temporal and spatial correlations, and provide observational evidence for understanding thermal instability, coronal energy transfer, and mass circulation. Using multi-band observational data from SDO/AIA and ASO-S/SDI, combined with differential emission measure (DEM), light curves, and time-distance analysis, this study systematically investigates the coronal waves, coronal loop evolution, and coronal rain events associated with the X5.0-class flare in the active region (AR) 13536 on 2023 December 31. The filament eruption triggers the propagation of coronal waves, which induce loop lifting and damped oscillations (period ∼ 177 s; damping decay time ∼ 526 s). Coronal rain was detected in both SDO/AIA 304 Å and ASO-S/SDI 1216 Å images, with two distinct coronal loop bundles (L1 and L2) showing different evolution features: L1 exhibits an enhanced intensity and quantity of coronal rain, while new coronal rain forms along L2 after the eruption. The coronal rain in L2 exhibits a clear north-south asymmetry in its kinematics. Along the northern leg, the rain comprises two regimes: early blobs that fall at high, quasi-constant speeds exceeding 150 km s -1 , and later blobs that descend with an acceleration of 0.052 km s⁻2, reaching a peak speed of 86 km s⁻1. In contrast, along the southern leg, the rain descends steadily at low speeds below 40 km s^ -1 . Analysis of temperature variation using the DEM and response fit (RFit) methods supports the onset of thermal instability in the coronal loops. Our findings demonstrate that coronal waves can trigger thermal instability that drives and enhances coronal rain formation. This study provides direct observational evidence that external fast wave perturbations can play a major role in coronal rain formation. This result can have important implications for the formation of cool plasma in other settings, such as flare-driven rain.