A spectral approach to the origin and propagation of magnetoacoustics oscillations in the network and internetwork areas of solar granules

Document Type : Research Article


1 Associate Professor, Department of Physics, Payame Noor University (PNU), Tehran, Iran

2 M.Sc. Student, Department of Physics, Payame Noor University (PNU), Tehran, Iran


In this paper, a spectral approach to the origin and propagation of magnetoacoustic oscillations in the network and internetwork areas of solar granules is performed. The data used in this study are mostly from Interface Region Imaging Spectrometer (IRIS). Slit Jaw Images (SJIs) data of IRIS at wavelengths of 1400 angstroms related to Si IV and 2796 angstroms related to Mg II h / k and 2832 angstroms related to Mg II w s, are used to select network and internetwork areas. The data of the Mg II k spectrum with a wavelength of 2796 angstroms and a temperature of 10,000 Kelvin have been used to construct the temporal profile of the intensity at the peaks of h3, k3, h2r, h2v, k2r and k2v, and the prospective profile of intensity temperature. One of the common methods for temporal and frequential characteristics analysis is the use of wavelet analysis. This method seems to be a practical method due to the variety and flexibility of wavelet types for different types of analysis. Wavelets and their convolution with waves lead to the extraction of time, frequency and power data. It should be noted that due to the uncertainty principle, resolution of time and frequency interact and its need to select optimum limit of the time and frequency resolution. One of the reasons for choosing Morlet Wavelet for the analysis of this study is the lack of a sharp edge, which reduces the ripple and improves the accuracy of detect the fluctuations properties. Another and one of the most important reasons for using the Morlet wavelet is that it does not change the temporal resolution of the wave. For these reasons, Morlett 5 was the most sensible and reliable choice for high-temporal and frequency-specific results for this study. Using wavelet analysis, the oscillation characteristics of the intensity are obtained in the network areas and internetwork areas. By Investigation of the intensity profiles in h and k peaks, it was found that the general behavior in them was the same and the only difference was in the intensities of these peaks and therefore their temperatures. In the case of intensity temperature profiles, the general behavior for intensity temperature profiles extracted from h and k peaks, also seems to be the same. By investigation of the wavelet analysis results, it appears that the oscillating behavior at the h and k peaks is almost similar. Using the results of wavelet analysis, in this study, the periods of oscillations in the intensities of bright points in the network and internetwork have been obtained. According to their values, it seems that the bright points of the internetwork have a photospheric origin and the bright points of the network have a chromospheric origin. Another result of the wavelet analysis of this study was the intensity of oscillations with a period of about 64 seconds. This high frequency differs from the solar researchers’ observations of photosphere and chromosphere oscillations, so it cannot be related to those oscillations. It seems that this is the first time that this type of high frequency oscillations has been reported. It seems that these high frequency oscillations can play an important role in heating the TR. For this reason, Accurate study of these high frequency oscillations is necessary to understand the causes and heating mechanisms of TR. These high frequency oscillations have been seen in almost all data and areas under study, so far there is no strong evidence of the origin and cause of these high frequency oscillations, and we hope that with more detailed and extensive studies we can better understand the properties and reason of these oscillations.


Main Subjects

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