الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 32 |  |  |
| | | from | 32 | | |
Abstract
One of the most crucial pieces of information needed in astronomy is the distance to stars and cosmic groups.
A new statistical method for cosmic distances determination was developed. The method depends on the assumption that the members of the group scatter around a mean absolute magnitude in Gaussian distribution. The mean apparent magnitude of the members is then expressed by frequency function to correct for observational incompleteness at the faint end. The problem is reduced to the solution of a highly transcendental equation for a given magnitude parameter (α).Full Computational developments of the method was recently established.
The present thesis is addressed to study three important subjects in the field of astrophysics (galactic structure).
The first subject we present an introduction about the two subjects of present thesis and some importantdefinitions.
The secondsubject is dealing with the distance of stellar groups. For this study we use the same assumptions, and transcendental equation but with new semi analytical solution of the distance, compute the distance of selected stellar groups using developed methods, establish the frequency functions Ф (M) and ψ (m) of absolute and apparent magnitudes for the selected stellar groups, provide some basic descriptive statistical parameters for apparent and absolute magnitudes of some selected stellar groups.
In the third subject the importance of the velocity ellipsoidparameters is due to their connection to the most important mathematical function of stellar astronomy, which is, the phase density function. This function entirely defines the state of the stellar system. If this function is known, all other distribution functions used in stellar astronomy can be mathematically derived from it. In particular the size, shape and motion of the system at any instant can be found. The velocity ellipsoid parameters were treated analytically using vectors and matrices analyses. This method developed a general computational algorithm for the basic parameters from the exact solutions of the equations involved.
In this thesis we determine the velocity ellipsoid parameters of the same stellar groups, study correlations between these kinematical properties for certain stellar groups (i.e. velocity ellipsoid parameters) with their physical ones (e.g. stellar spectral types).
We classify these stars according to their spectral types into five classes(i.e. B, A, F, G, K and M), where these are no O type, we ignore O type where they have 5 and 2 stars, respectively, which have no correct indication with statistics.