Fredagskollokvium: What causes high-frequency oscillations in active region moss: Waves or/and Reconnection?
Nancy Narang, Rosseland Centre for Solar Physics, Institute of Theoretical Astrophysics (UiO).
Dr. Nancy Narang, Postdoctoral fellow of Rosseland Centre for Solar Physics (UiO). Photo: Daniel E. Nóbrega Siverio /UiO
The high temporal, spatial and spectral resolution of Interface Region Imaging Spectrograph (IRIS) has provided new insights into the understanding of different small-scale processes occurring at the chromospheric and transition region heights. I will present a study of the dynamics of high-frequency oscillations of an active region (AR 2376) moss as recorded by simultaneous imaging and spectral data of IRIS. Wavelet transformations and power maps from slit-jaw images in Si IV 1400 Å passband, and sit-and-stare spectroscopic observations of Si IV 1403 Å spectral line reveal the presence of high-frequency oscillations with ~1-2 minutes periods in the bright moss regions. The presence of such low periodicities is further confirmed by intrinsic mode functions (IMFs) as obtained by empirical mode decomposition (EMD) technique. I will show the evidence of the presence of slow waves and reconnection-like events, and that together they cause the high-frequency oscillations in the bright moss regions.