7 results on '"Zeighami, Sima"'
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2. Waves propagation in network and inter-network bright points channels between the chromosphere and transition regions with IRIS observations
- Author
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Zeighami, Sima, Tavabi, Ehsan, and Amirkhanlou, Elnaz
- Published
- 2020
- Full Text
- View/download PDF
3. Space Climate and Solar Energetic Particles.
- Author
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Tavabi, Ehsan, Zeighami, Sima, and Kharaghani, Yones
- Subjects
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SOLAR energetic particles , *GLOBAL warming , *CLIMATE change , *SOLAR activity ,MAGNETIC fields in the solar corona - Abstract
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. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
4. Review of Fast Solar Jets and Coronal Mass Ejections.
- Author
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Zeighami, Sima and Tavabi, Ehsan
- Subjects
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SOLAR activity , *CORONAL mass ejections , *MAGNETIC energy storage , *HELIOSPHERE , *SOLAR corona , *SUN - Abstract
The Sun is a magnetically active star. It has a powerful magnetic field that shifts slightly from year to year until it reverses about every eleven years. The sun's magnetic field has many effects, the collection of which is called solar activity such as, sunspots, solar ares, and coronal mass ejections (CMEs). Currently, it is only possible to predict a magnetic storm 30 to 60 minutes before it occurs, which is a very short time. Solar ares and CMEs, massive eruptions of superheated plasma, are the two most energetic phenomenon which impulsively ejected and accelerated by releasing magnetic energy in the solar corona. Heliosphere, space weather, and the Earth are affected from trans-porting coronal plasma. Following the occurrence of these phenomenon in the Sun, the solar wind blows with greater speed and intensity and sends energetic charged particles into the space of the solar system. When these particles reach the Earth, their radiating electromagnetic waves interact with magnetic field of the Earth. Then various effects are observed, as shock waves and massive geomagnetic storms that disrupt satellites and power grids. Today, using the advancements of ground and space technology, the solar surface can be easily observed. Therefore, observation and prediction of solar storm will be possible more than in the past. In this paper, we review papers intended to collect comprehensive information about what has already been researched about fast solar jets and CMEs made by ground and space instruments over the last decades. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
5. Correlation of the Flux of Energetic Rays and Particles with the Solar Cycle.
- Author
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Tavabi, Ehsan, Zeighami, Sima, and Aleali, Ali
- Subjects
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SOLAR cycle , *SOLAR corona , *X-rays , *MAGNETIC fields , *ELECTRONS - Abstract
A solar flare is a sudden flash that occurs near the solar surface. This results in the emission of an extensive range of energy from the surface of the Sun. These giant explosions generally contain X-rays and energy that tend to travel in all directions at the speed of light. Coronal mass ejections (CMEs) are types of explosions that occur on the solar surface. A CMEs releases a large amount of plasma and magnetic field. Our main goal in this research is to prove that the reason for the release of charged particles, protons, electrons and X-ray radiation, followed by the release of solar winds, is the occurrence of flares and CMEs. The occurrence of this phenomenon is related to other phenomena, such as the magnetic field of the Sun's surface, the cycle of the Sun's activity, sunspots, the emission of charged particles of electrons and protons from the solar corona, the rate of occurrence of CMEs from the corona, the average and maximum speed of CME and X-ray radiation in the category Class X, which is the highest energy category for X-ray radiation, is directly and closely related. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
6. Chromosphere Activity Relation with Solar Dynamo Magnetic Activity Cycle.
- Author
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Tavabi, Ehsan, Rajabi, Mina, and Zeighami, Sima
- Subjects
SUNSPOTS ,SOLAR chromosphere ,TELESCOPES ,WAVELENGTHS - Abstract
In this article, we analyzed the abnormal thickness of the chromosphere above the coronal holes (CH) at the poles of the Sun for 13 years (2010-2022), on the 15th of every month, by using AIA/SDO telescope data. We used the light emitted from helium-2 (He II) at a wavelength of 304 Å at about 50,000 K to investigate the solar holes in its north and south poles. This light is emitted from the chromosphere and the transition region. According to the values of the graphs obtained by the MATLAB program and the comparison between solar cycles during the 2010-2022 years, it was seen that the Full width of the intensity curves at half maximum (FWHM) in the poles, and as a result the magnetic activity of the sun and especially the activity of coronal cavities as the main source of the solar dipole magnetic field before cycle 25 is significantly greater than this thickness before cycle 24. According to the relationship between the number of sunspots and the solar activity in the coronal holes at the solar poles with a time delay of 2 to 5 years, we expect the maximum increasing in the number of sunspots around the year 2025. As a result, in terms of the number of sunspots, the height of the solar cycle 25 is probably higher than the cycle 24, which was a low sunspot number cycle. We also concluded that the thickness of the chromosphere has an inverse relationship with solar dynamo magnetic activity cycle. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
7. Chromospheric Jets and Their Properties.
- Author
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Tavabi, Ehsan and Zeighami, Sima
- Subjects
- *
SOLAR chromosphere , *OSCILLATIONS , *IMAGE processing , *SOLAR wind , *ENERGY transfer - Abstract
In this study, we review solar chromospheric jets and characteristics of them. The chromosphere and transition region are the interface between the solar photosphere and the corona, which plays a key role in the formation and acceleration of the solar wind. In recent years, scientists have made great efforts to understand the mechanism of energy transfer in the solar chromosphere and corona. The researchers suggest that the key to solving this problem may lie in understanding the nature of the small-scale transient events that are distributed across the surface of the Sun. Of these, solar spicules are the most prominent small-scale dynamical phenomena in the chromospheric regions that drive relatively cold material from the lower chromosphere to the corona. Spicules can heat the corona both by ejecting hot plasma and by energy transfer by magnetohydrodynamic (MHD) waves. These dynamical structures are formed when photospheric oscillations and convective ow along the magnetic field lines penetrate into the chromosphere. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
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