Iranian Journal of Astronomy and Astrophysics
https://ijaa.du.ac.ir/
Iranian Journal of Astronomy and Astrophysicsendaily1Wed, 03 Apr 2024 00:00:00 +0330Wed, 03 Apr 2024 00:00:00 +0330Space Climate and Solar Energetic Particles
https://ijaa.du.ac.ir/article_397.html
In this paper, we investigate the effect of solar corona magnetic activities during 11-year periods and energetic particles on global warming. According to atmospheric changes during the past years, the relationship between these two issues should be investigated. How the activities of the solar corona affect the average temperature of the Earth and also the increase in its temperature, have been the attention of researchers in recent years. For this purpose, we use the source of data recorded from the momentary position of the Sun in reliable sites, as well as information recorded from the flow of cosmic particles on the surface of the Earth by the GOES (Geostationary Operational Environmental Satellite) detector, which belongs to the NASA space agency. Solar activity affects the Earth's geomagnetic field and creates a geoelectric field on the Earth's surface. This phenomenon can affect technological systems, such as power grids, oil and gas pipelines, and railway systems, leading to damage to power grids, equipment, line breaks, and even blackouts. Results of this study show that there is a significant relationship between the magnetic activities of the Sun in 11-year cycles and the temperature of the Earth, which can be considered an essential parameter in predicting many crises and climate changes on the Earth's surface. Our results also indicated that changes in the number of sunspots and cosmic particles are inversely to each other.Measurement of Atmospheric Neutrino Cross-Sections on Oxygen, Water and Argon using Nuwro Event Generator
https://ijaa.du.ac.ir/article_398.html
Neutrinos were produced immediately after Big-bang. These are the most abundant particles after photons. Neutrinos are literally jam packing the Universe and are associated with some of the deepest mysteries of nature. These are excellent carriers of information from the past of Universe through sources like bursting stars and black holes which we do not have a direct access to. Consequently, there has been a surge in the study of neutrinos and their interaction with matter. However, since neutrinos are very weakly interacting particles, these have feeble cross-sections. Nonetheless, cross-section measurement is the basic ingredient for any higher order neutrino studies. Therefore, in this work we report the cross-section measurements of neutrino interactions with three atmospheric gases viz; Oxygen, Water and Argon. This study is done using NuWro event generator. Nuwro is a Polish code developed by some eminent researchers at Wroclaw University of Poland. It is configured using well known physical models of neutrino interaction. The cross-section measurements are taken in an energy interval of hundreds of MeV to a few GeV,which is also best suited to study neutrino oscillations. We also try a novel way to define the scattering potential for neutrino interactions as a function of initial neutrino flux.Analytical Expression of the Beam-Plasma Particles Distribution Function Effect on the Electromagnetic Instability Growth Rate in Strongly Coupled Plasmas
https://ijaa.du.ac.ir/article_408.html
The beam-plasma particles distribution function is one of the parameters which plays an important role in the energy-traveling mechanism of the relativistic electrons generated by the laser-plasma interaction in the Inertial Confinement Fusion Plasma. This paper investigates an analytical expression of the beam-plasma particles distribution function effect such as the Kappa, Semi-relativistic Maxwellian and bi-Maxwell distributions on the Weibel electromagnetic instability growth rate in strongly coupled plasmas under the low-frequency wave condition. The obtained results show that the maximum growth rate of the beam- plasma particles with semi-Maxwell distribution function is based on the temperature anisotropy parameter, density gradient, quantum and relativistic parameters has the highest possible value compared to the other two beam-plasma particles distribution functions. Also, the bi-Maxwellian distribution function has a more stable growth rate than the Kappa and the semi-Maxwell distribution functions.Quark Stars in Generalized Hybrid Metric-Palatini Gravity
https://ijaa.du.ac.ir/article_409.html
We investigate the physical properties of quark stars with two different equations of state in generalized hybrid metric-Palatini gravity. This theory corresponds to a bi-scalar gravitational theory with two non-minimally-coupled scalar fields.The field equations of the metric tensor and scalar fields are derived by varying the action with respect to the dynamical fields. We obtain the field equations for static spherically symmetric geometry interior of compact objects. The numerical solutions for two types of quark stars, the MIT bag and CFL model are studied. The solutions reveal the structure of the compact objects. The solutions are obtained for different values of the model parameters. All considered cases show that compact objects are more massive than their general relativity counterpart. The surface redshift and compactness are also obtained which shows that the generalized hybrid metric-Palatini quark stars have higher surface redshift and are more compact than general relativity quark stars.Spatial Variations in the Characteristics of Oscillated and Non-Oscillated Solar Bright Points in Active Regions and Coronal Holes
https://ijaa.du.ac.ir/article_410.html
In this study, researchers investigated the properties of oscillated and non-oscillated bright points (BPs) in different regions of the Sun, including active regions (ARs) and coronal holes (CHs). The findings revealed both differences and similarities among these BPs across the various regions. Firstly, the study observed that internetwork BPs in ARs exhibited higher damping times compared to network BPs. Additionally, internetwork BPs in ARs displayed wider ranges of maximum Doppler velocities in comparison to network BPs. Although both forms of BPs had comparable damping times, internetwork BPs demonstrated greater maximum Doppler velocities than network BPs. Moreover, the study provided insights into the damping behavior of BPs in different regions. Specifically, it was noted that the majority of network BPs in ARs exhibited overdamping, indicating that the damping effects were dominant. On the other hand, in CHs, internetwork BPs displayed overdamping behavior, suggesting a similar dominance of damping effects. In contrast, oscillated network BPs in CHs exhibited critical damping behavior, implying a balance between damping and driving forces. It is important to emphasize that the physical principles underlying BP damping may vary depending on the local plasma conditions and magnetic surroundings. Overall, this study highlights the diverse characteristics of BPs in different solar regions, shedding light on their damping times, maximum Doppler velocities, and damping behaviors. These findings contribute to our understanding of the intricate dynamics and plasma conditions occurring in different areas of the Sun, providing valuable insights into the complex nature of solar phenomena.