Petrova, E. ; Van Doorsselaere, T. ; van Noort, M. ; Berghmans, D. ; Castellanos Durán, J. S.

published in Astronomy & Astrophysics, 697 issue id.A168 (2025)

Abstract: Context. Fine-scale structures of the solar chromosphere, particularly fibrils, are known to host various types of magnetohydrodynamic (MHD) waves that can transport energy to the corona. In particular, absorption features observed in the Hα channel have been widely detected that exhibit transverse oscillations. Aims. We aimed to detect a high-frequency transverse oscillation in fibrils. Methods. We conducted a case study on a high-frequency transverse oscillation in a chromospheric fibril. A chromospheric fibril was observed on 24 August 2018, in the Hα spectral line, with the prototype Microlensed Hyperspectral Imager (MiHI) at the Swedish 1-meter Solar Telescope. The MiHI instrument is an integral field spectrograph capable of achieving ultra-high resolution simultaneously in the spatial, temporal, and spectral domains. Results. The detected oscillation characteristics include a period of 15 s and a displacement amplitude of 42 km. Using the bisector method, we derived Doppler velocities and determined that the polarisation of the oscillation was elliptical. Conclusions. The energy contained in the oscillation ranges from 390 to 2300 W/m2, which is not sufficient to balance radiative losses of the chromosphere.

Keyword(s): transverse waves ; chromosphere ; Microlensed Hyperspectral Imager ; SST
DOI: 10.1051/0004-6361/202452925
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