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). 

Bildet kan inneholde: klær, hår, øyenbryn, hake, panne.

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.

Moss region observed in (left) corona by Solar Dynamics Observatory & (right) transition region by Interface Region Imaging Spectrograph. Credits: Nancy Narang (Narang et al. 2019, Frontiers in Astronomy & Space Sciences)

Please join via Zoom at

Meeting ID: 648 0201 3686
Passcode: 703162

Attendees will be muted during the colloquium, but will have the opportunity to ask questions at the end by clicking on the "raise hand” button (or send a request to me via chat).

Publisert 19. mars 2020 07:00 - Sist endret 30. okt. 2020 10:23