The Researches Of Mass Loss Rates In Stellar Evolution

The Stellar Wind is common in every kind of stars, and has a great impact on Stellar Evolution, Interstellar Medium, and so on. The Stellar Wind can bring out mass loss in the evolutional process. The Mass Loss Rates is one of most important characteristics of describing the Stellar Wind. Many kind of mass loss formulas were raised by previous authors. Researchers have to choose which one to be used in their stellar evolution calculation. In2000Catelan suggested that "using several different mass loss formulae constitutes a better approach than relying in a single one." In order to use different mass loss formulae, the stellar evolution process was divided into different evolution stages. Although Scholars has begun to adopt different mass loss rate formula in their research, no one has focused on those problems concerning to mass loss rate formula roundly and carefully.The inner structure of star is very complicated and varied in different evolutional stages. Therefore, the mass loss rate formula is a consecutive piecewise function in the stellar evolution calculations according to evolutional stages of star. We calculated the stellar evolution of stars whose mass range from3M⊙to9M⊙. By studying the variety of inner structure of stars, an attitude that different demarcation point of stellar evolutional stages can affects the evolutionary track in the Hertzsprung-Russell diagram is developed, based on mass loss rate is a consecutive piecewise function in the stellar evolution calculations. After that,2evolutional models with different demarcation point have been computed; a conclusion was provided that it is more suitable to choose the lowest luminosity in the Hayashi line as the demarcation point as the demarcation point between the evolution stage1and2than to choose the moment which abundance of Hydrogen of core equal to zero, according to the continuity of mass loss rate function.Furthermore, by studying the variety of evolutionary track and evolution of the central values of temperature and density, we found that choosing different mass loss rate formula has significant impact on evolutionary track. The more the star’s mass, the more significant of the impact. A conclusion was provided that mass loss rate formula of Schroder and Cuntz is better than any other4traditional formulae, by studying variety of the curves of mass loss rate along time. The mass loss rate predicted by their formula is Increasing function in the evolutionary stage2, which corresponds with observation.Finally, a formula set and a demarcation point which were applied to stellar evolution calculation were provided. Reimers’Law was adopted in the evolutionary stage1. The formula of Schroder and Cuntz was used in the evolutionary stage2. The demarcation point between evolutionary stage1and2is the lowest luminosity in the Hayashi line.