對於分子雲裡的雙星系統，我們提出兩種模型去描述雲 (或雲核) 的擴散。我 們發現當初始半徑和初速越大或雲氣質量越大，系統傾向為自由狀態。擴散時間對 系統的作用依照不同的環境密度會有不同的影響，當環境密度較小時，擴散時間對 系統有很大的影響，對於環境密度較大時，不同的擴散時間會讓此系統處於束縛和 自由間轉換。;We study the dynamics of a binary system under different mass loss scenarios. We are particularly interested in the conditions under which the system remains bound or not when the mass loss process is stopped. We study two cases. The first one is the binary system is an isolated system and one of the stars change its mass for a finite time. The second one is the binary system is embedded in molecular cloud (or cloud core) and the cloud (or cloud core) is dispersing or losing mass.
For the isolated binary system, we consider three different systems. (1) The host star is much heavier than the companion star, and we study mass loss by (a) host star (b) companion star. (2) Both stars has similar mass, and mass loss by one star (3) the total mass is unchanged, mass transfer from one star to the other. Most of them have similar results. For example, the system is more likely to be unbound if the mass loss is large. Also there is a general trend that for a fix mass loss, the longer is the time interval of mass loss, the more likely is the system remains bound. However, this trend is not necessary monotonic. It may happen that the system may alternate between bound and unbound destiny when the time interval of mass loss increases within a certain range.
For embedded the binary system, we propose two models for cloud dispersion. We find that the binary system is more likely to be unbound if the initial position is larger, or initial velocity is faster, or the mass of cloud is larger. The dependence of dispersion time is complicated. When the density of interstellar medium is small, the time of dispersion has a great impact on system. When the density of interstellar medium is large, the increase in dispersion time may cause the system to alternate between bound and unbound destiny
