Distribution of plasma flow velocity field at the base of chromospheric jets

Authors

1 M.Sc. Student, Department of Physics, Payame Noor University, zanjan, Iran

2 Associate Professor, Department of Physics, Payame Noor University, Tehran, Iran

3 Assistant Professor, Department of Physics, Tabriz Branch, Islamic Azad University, Tabriz, Iran

Abstract

The sun is constantly throwing ionized particles out of its surface and causing solar storms. Various investigations have been carried out for finding out the origin of these storms for 50 years, in the photosphere, corona, and chromosphere. Large-scale coronal holes are usually areas that are definitely accepted for origin of the storms. However, research is still being done in other areas. Network jets are one of the issues that we have tried to investigate the distribution of their velocity field and their structures and also their role in plasma flows. Oscillations and transverse displacement of the jet axis can be interpreted as the presence of transverse waves along their axis. The two types of waves responsible for these fluctuations are magneto-hydrodynamic waves and alfvenic waves. In this paper, we studied the transverse displacement of the network jet axis, with the FLCT algorithm under IDL. The FLCT method is widely used to obtain the speed of moving features. The observed area is so large that we can identify many of the network jets. After choosing the coordinates of the item using the FLCT algorithm, we intend to obtain the Alfven velocity of the desired coordinates. The FLCT algorithm is a mathematical program used to construct a two-dimensional velocity field of connected images. The calculation of speed in this method depends on three factors: 1. Isolate the point on the image, 2- Calculation of correlation function between two images, 3. Peak location of the mutual correlation function, calculated for each pixel of the velocity. The FLCT algorithm uses interpolation to eliminate the complexity of the fixed angle on the center of the images. In results we can see the images analyzed in the IDL program, using MATLAB software to show the speed vectors that are torsional and indicate the speed of the alphabet. The images are in pixels and each pixel are is 0.3 sec. We estimated the chromosphere mass velocity of about 20 kms-1 using FLCT. Some of the network jets in the images seem to be other than the second type solar spicules sticks. However, we noticed that the speed of the jets is generally twice as large as the second type of sticks, which indicates the high contribution of these jets to the mass and energy of the solar atmosphere. We have noticed that network jets are important regardless of their relationship with second-generation sticks. A bunch of network jets is considered as an example of a jet. The network jet mechanism demonstrates the dynamics of the jets with high speeds (close to the speed of the Alfven in the interface area), which allows magnetic reconnection between the small magnetic rings and the background. Based on observational findings, several theoretical models and numerical simulations have been developed to describe the mechanism of these structures. Of course, unlike the remarkable improvements created by very accurate observations and the expansion of numerical theories and simulations, it is still unclear and their mutual relationship, their physical parameters, the definition of their formation mechanism and their possible role in the solar corona heat is unknown. These ambiguities are mainly due to the difference in the appearance of these phenomena when viewed in a variety of spectral lines.

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Journal of the Earth and Space Physics
Volume 44, Issue 3
November 2018
Pages 671-677

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