2025年7月25日（金）　

氏名　内藤 由浩

自己紹介: 

総合研究大学院大学D2

Penetrating waves along spicules to the corona

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概要： Alfvénic waves, observed as the transverse motion of spicules (jets extending along magnetic field lines) in the chromosphere, are among the most promising candidates for heating the solar corona and accelerating the solar wind in polar coronal holes.  Here, we conducted a statistical study of Alfvénic waves along spicules in polar coronal holes using Si IV spectra observed by the Interface Region Imaging Spectrograph (IRIS) to determine whether sufficient wave energy can penetrate into the corona, even considering wave reflection at the transition region. We developed a technique for wave detection, wave-mode identification, and energy flux estimation for each detected wave using the line-of-sight (LOS) velocity and intensity. 120 waves were detected, including 65 ascending Alfvénic waves, 43 descending Alfvénic waves, 6 ascending slow-mode waves, and 6 descending slow-mode waves. Taking into account the random orientation of transverse motions relative to the LOS direction, the average energy fluxes of ascending and descending Alfvénic waves were estimated to be 2.1 × 105 erg cm^−2 s^−1 and 1.1 × 105 erg cm^−2 s^−1, respectively. Assuming that a fraction of ascending Alfvénic waves are reflected at the transition region and then observed as descending Alfvénic waves, the energy flux penetrating into the corona is 1.0 × 105 erg cm^−2 s^−1. We also identified multiple velocity components in the observed spectra, suggesting that the energy flux may be underestimated by a factor of 4 to 9. This study presents the first observational estimates of the energy flux of Alfvénic waves that penetrate into the corona. Our results demonstrate that Alfvénic waves carry sufficient energy for the coronal heating and the solar wind acceleration, even considering the wave reflection at the transition region.