Document Details

Document Type : Thesis 
Document Title :
Simulation models for Star Formation, newly-born Stars, and in Stars in Final Evolutionally Stage
نماذج محاكاة لتكوين النجوم والنجوم حديثة الولادة والنجوم في مرحلة تطويرها النهائي
 
Subject : Astronomy 
Document Language : Arabic 
Abstract : Polytropic models are vital for two classes of theoretical astrophysics: stellar structure and cosmic dynamics .In fact, the polytrope representation of stars models, is a method that today still lends valuable technique and insights to the internal structure of stars .It is also proven to be most versatile in examination of a variety of situations, including the analysis of isothermal cores, convective stellar interiors and fully degenerate stellar configurations. In cosmic dynamics, the Lane-Emden equation of the polytropic equilibrium configurations is considered as generating function of potential models for flattened galactic systems; upon such potentials the forces and the star orbits in these systems could be determined. Moreover, the effects of a positive cosmological constant on astrophysical and cosmological configurations described by polytrobic equation of state. In brief great efforts has been devoted up to now, and is being devoted at present to express some characteristic physical parameters related to ploytrobic models. In the present thesis, two problems are established: First, literal analytical expressions in power series forms are established for the physical characteristics of ploytrobic stellar models and most of them are illustrated by three dimensional and contour plots. The importance of these expressions is due to some factors of these are: (i) their analytical forms, offer in general much deeper insight into the nature of the physical characteristics to which they refer. (ii)These expressions are general in the sense that they could be used for any polytropic index ( n so they can suit many of the applications. (iii)The coefficients of each of these expressions have been found directly without the use of recurrence formulae. Second, homogeneous stellar models are established using two composite polytropes, one polytrope for the convective core, while the other polytropes for the outer radiative zone. The observed mass-luminosity relation and the place of the Zero Age Main Sequence are sufficiently well reproduced by our models. The differ¬ences in the effective temperature and the luminosity between our models and the professional models then nearly vanish for most of the masses considered. Finally, I succeed to set up to the first time six new analytical relations for the homogeneous stellar models between: 1- Mass-Luminosity ( . 2-Radius- Luminosity ( . 3- Radius-Effective Temperature ( ). 4- Luminosity ( -Effective Temperature ( ) [place in HR-diagram]. 5- Radius- Mass. 6- Mass- Effective Temperature ( ). These relations are extremely accurate as indicated in the error analysis report of each relation. 
Supervisor : Prof. Mohammed Adel Sharaf 
Thesis Type : Master Thesis 
Publishing Year : 1430 AH
2009 AD 
Co-Supervisor : Dr. Majdy Al-Saftawy 
Added Date : Saturday, December 4, 2010 

Researchers

Researcher Name (Arabic)Researcher Name (English)Researcher TypeDr GradeEmail
العنود عبدالله العموديAL-AMODI, ALANOUD ABDULLAHResearcherMaster 

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