| Authors : | Kartika Sangal 1 , P. Kayshap 2 , Abhinav Prasad 1 , A.K. Srivastava 1
1. Department of Physics, Indian Institute of Technology (BHU), Varanasi-221005, India
2. Vellore Institute of Technology, Kotri Kalan, Ashta, Near, Indore Road, Bhopal, Madhya
Pradesh ,46611 |
| Abstract : | Using the Interface Region Imaging Spectrograph (IRIS) sit and stare observations of the
quiet sun , we shed new light on the physical nature of the solar transition region (TR)
oscillations. For this investigation, we utilize Si IV 1393 angstrom spectral line. We study
the oscillations in the transition region by examining the statistical distribution of power and
associated significant periodicities in different regions, such as above the bright magnetic
network and dark non-magnetic regions. We use a wavelet analysis tool (e.g., power,
cross power, coherence, and phase difference) combined with the generic noise model
(i.e., power-law + constant) to detect the nature of oscillations at these locations. We
provide the detailed period distribution of the observed significant periods in the bright
region and dark region. At the bright locations, we find that the mean period is 6 min in
intensity and 7 min in the velocity histograms, respectively. These distributions are
consistent with each other in the 1-sigma limit. The phase between intensity and velocity is
distributed between -180° and 180° in the bright locations, with three peaks at -120°, 30°,
and 100°. At the dark locations, the mean period is 6 min in the intensity and 5 min in the
velocity histograms, respectively. The phase between intensity and velocity is distributed
between -180° and 180° in the dark locations, with three peaks at -160°, 0°, and 180°. We
interpret these observations as an evolution of the slow magnetoacoustic oscillations in the
localized non-ideal solar atmosphere, and their signature in the TR layer. |
