Multi-thermal dynamics and transverse oscillations of solar spicules revealed by coordinated SST, IRIS, and SDO observations

Abstract

% context heading (optional) {Solar spicules are highly dynamic chromospheric jets that play an important role in the mass and energy balance of the solar atmosphere, though their connection to the transition region and corona remains unclear.} % aims heading (mandatory) {We investigate the dynamical and multi-thermal properties of spicules, their connection to higher atmospheric layers, and their transverse oscillations and associated energy flux.} % methods heading (mandatory) {We analyse coordinated high-resolution observations from the Swedish 1-m Solar Telescope (SST) in H$α$, the Interface Region Imaging Spectrograph (IRIS) in \ion{Si}{iv} 1400~Å, and the Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA) coronal channels. Space-time diagrams, spectral analysis, and wavelet techniques are used to study temporal evolution, Doppler velocities, and oscillatory properties. Transverse displacements of spicules are tracked to estimate wave properties and energy flux.} % results heading {Space-time analysis reveals a clear correspondence between chromospheric spicules and coronal emission in AIA 171~Å, evolving coherently with spicule extension. Doppler velocities from H$α$ and \ion{Si}{iv} show opposite signs, indicating multi-thermal plasma flows. Wavelet analysis reveals frequently dominant $\sim$3-minute oscillations, along with high-frequency transverse oscillations (65--270~s) with velocity amplitudes of 3.3--9.9~km~s$^{-1}$ and a mean energy flux of $(2.14 \pm 0.78)\times10^{3}$~W~m$^{-2}$.} % conclusions heading (optional) {These results demonstrate that spicules are multithermal, dynamic structures connected to the transition region and corona, and that transverse waves carry substantial energy, highlighting their role in coronal heating.}