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MOHAMMAD JAVAD KALAEE
Articles written in Journal of Astrophysics and Astronomy
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Volume 41 All articles Published: 20 February 2020 Article ID 0002
MHD shock waves and discontinuities are often observed in the solar wind. We studied a strong shock wave event on 7 June 2014, during a solar maximum. The properties of forward shock are investigated and all physical parameters of interplanetary shock are analyzed. The upstream parameters, such as Alfvenvelocity and sound speed are calculated, and the angle ($\theta$) between the upstream magnetic field direction and the shock normal is estimated. To determine the propagation speed of the shock, a full numerical solution ofshock adiabatic equation is carried out. The thermal pressure for electrons and ions are calculated and also the pressure ratio and the entropy change across the shock are estimated. The results show that the shock strengthis about 3.88 with $\theta \approx 72^{\circ}$ (a quasi-perpendicular case), and shock propagation velocity is about 678 km/s. The increase in the specific entropy is also evaluated.
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Volume 42 All articles Published: 25 May 2021 Article ID 0018
A computational study of the Langmuir wave instability event in the solar wind during solar maximum
Several kinds of instabilities are often observed in the solar wind. Langmuir waves have been observed using wideband plasma wave measurements on several spacecrafts such as the Galileo spacecraft. We studied the Langmuir wave instability event in the solar wind on 10 December 1990, during a solarmaximum. On this date, highly structured bursts and Langmuir waves have been observed by the Galileo spacecraft. We used the dispersion relation in hot magnetized plasma to calculate the Langmuir wave instability properties. The properties of Langmuir wave instability are investigated and all physicalparameters of interplanetary in around 1 AU are analyzed. The instability parameters, such as wave frequency, the thermal velocity and the damping rate are calculated. The results show that the damping rate of Langmuir waves increases with increasing the frequency of Langmuir waves. Also, the lowest damping rate decreases with increase in the wave normal angle. The results show that a good agreement between computational results and Langmuir waves has been observed by the Galileo spacecraft on 10 December 1990.
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Journal of Astrophysics and Astronomy
Volume 42, 2021
All articles
Continuous Article Publishing mode
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Journal of Astrophysics and Astronomy | News
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Continuous Article Publication
Posted on January 27, 2016Since January 2016, the Journal of Astrophysics and Astronomy has moved to Continuous Article Publishing (CAP) mode. This means that each accepted article is being published immediately online with DOI and article citation ID with starting page number 1. Articles are also visible in Web of Science immediately. All these have helped shorten the publication time and have improved the visibility of the articles.
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Editorial Note on Continuous Article Publication
Posted on July 25, 2019Click here for Editorial Note on CAP Mode
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