Coronal Heating and Seismology: Constraints from Multi‑Wavelength Observations Across Loops of Different Active Regions

The solar corona, with its million-degree temperatures, represents a classical problem: how does energy transfer from the photosphere Corona with its million degrees temperatures is an example of classical problem of physics – how the energy transfer occurs from photosphere in order to keep such high level of heating? This work presents a state-of-the-art review of coronal seismology, incorporating recent observational data that constrain competing heating theories through multi-wavelength measurements in active regions. MHD waves and oscillations (kink, slow and sausage modes) observed in the loops of the corona are considered in detail. Special emphasis is given to the EUV imaging (SDO/AIA, Solar Orbiter/EUI) and spectroscopic (IRIS, Hinode/EIS) observations, which give significant contribution to the seismology inversion technique. In this context, the of the loops is probed, which demonstrates that neglecting temperature and density structure introduces systematic errors in magnetic field estimates derived from period ratios. Phase delay between the observations in hot (94 Å) and cool (171 Å) channels shows thermal and radiative oscillations, which give us information about the heating/cooling time-scales and effective polytropic index. The comparison of flaring (AR 11283) and non-flaring (AR 12194) active regions shows that flaring loops have a wider differential emission measure (DEM) distribution, higher-amplitude oscillations with greater damping, indicating a dynamic and intermittent heating process.