The Effect Of Rotation And Turbulent Pressure On The Stellar Evolution Of5M_⊙

The rotation of the stars is ignored in the classic stellar structure and evolution model. Without considering the rotation of the stars, equipotential surface in the stars is the spherically symmetric structure, so the stellar structure and evolution model can be simplified into one-dimensional model. Classic stellar structure and evolution model successfully explained the observation characteristics of most of stars at that time. But with the improvement of observation technology, scientists find that there exist lots of differences between the calculated result of evolution model of the classic stars and the latest observation results in recent decades. These differences indicate that the effect of stars rotation may make materials in the stars transfer outward and some element in stellar surface become super abundant. Although turbulent pressure is omitted generally, its inherent large-scale turbulence on convection region makes turbulent pressure inevitable. Therefore, studying the effect of stars rotation and the influence of turbulent pressure on stars evolution simultaneously has great significance.Considering the effect of rotation, equipotential surface in stars turns into spherically asymmetric structure, which causes stellar structure and evolution model turn into two-dimensional model. Based on the hypothesis of constant-pressure surface, we transfer stellar structure and evolution model into a one-dimensional model, and at the same time, introduce the effect of turbulent pressure. Thereby, the fluid statics balance in stars should be the balance of gravitation, radiation pressure, gas and turbulent pressure. Basted on it, this thesis studies carefully the structure and evolution of the stars ranging from main sequence stars to early AGB stars whose initial mass is5Mo.This paper presents stellar structure and evolution model considering effect of rotation and turbulent pressure. Based on the model, the Kippenhahn’s stellar structure and evolution procedures are corrected and the model is used to calculate the evolution of5Mo star from the main-sequence phase to the end of the early asymptotic giant branch (E-AGB) so as to study the influence of rotation effect and turbulent pressure on stellar structure and evolution. The results of the study are as follows:(1).The angular velocity of rotation varies.(2). Rotation effect has the great influence on star in the former stage of main sequence and in the latter stage of Red Giant through the angular velocity and the change of rotational angular velocity; turbulent pressure in the stage of AGB star.(3). why the stars which are rotating at a low speed approximate to sphericity observationally is explained.Thus, we think the influence of the stellar rotation on evolution of stars may be through the two ways:centrifugal effect on the angular velocity and effect on the rate of change of rotation velocity of the star. For stars rotating at a low speed, the influence on the star’s evolution from centrifugal effect brought about by angular velocity can even be ignored, but that by rate of change of rotation velocity can not. Therefore, to study stellar rotation, its effect could not be ignored on the stellar evolution no matter how small rotation angular velocity.