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

¹ Udaipur Solar Observatory, Physical Research Laboratory, Udaipur- 313001, India
² Indian Institute of Technology, Gandhinagar, Gujarat- 382355 India
³ Rosseland Centre for Solar Physics, University of Oslo, PO Box 1029 Blindern, 0315 Oslo, Norway
⁴ Institute of Theoretical Astrophysics, University of Oslo, PO Box 1029, Blindern, 0315 Oslo, Norway

^★ Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 14 April 2026
Accepted: 24 June 2026

Abstract

Context. Solar spicules are highly dynamic chromospheric jets that play an important role in the mass and energy balance of the solar atmosphere, even though their connection to the transition region and corona remains unclear.

Aims. We investigated the dynamical and multi-thermal properties of spicules, their connection to higher atmospheric layers, and their transverse oscillations and associated energy flux.

Methods. We analyzed coordinated high-resolution observations from the Swedish 1-m Solar Telescope in Hα, the Interface Region Imaging Spectrograph in Si IV 1400 Å, and the Solar Dynamics Observatory/Atmospheric Imaging Assembly coronal channels. Space-time diagrams, spectral analysis, and wavelet techniques were used to study temporal evolution, Doppler velocities, and oscillatory properties. Transverse displacements of spicules were tracked to estimate wave properties and energy flux.

Results. 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 Hα and Si IV show opposite signs, indicating multi-thermal plasma flows. Wavelet analysis reveals frequently dominant ~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 ± 0.78) × 10³ W m⁻².

Conclusions. These results demonstrate that spicules are multi-thermal dynamic structures connected to the transition region and corona and that transverse waves carry substantial energy, highlighting their role in coronal heating.