中文摘要：

目前，对大质量恒星形成的初始条件不很清楚，特别是大质量恒星是否形成于星团中心仍有争议．有人从时标上考虑，认为嵌埋星团的质量分层现象意味着大质量恒星只能在星团中心诞生．利用Monte Carlo方法对嵌埋星团的动力学演化进行了数值模拟，并与观测进行了比较．假设初始时刻大质量恒星随机分布，一定比例的嵌埋星团因为大质量恒星的随机运动，在演化的某个时刻会呈现暂态质量分层，其中一部分相当明显．这说明，大质量恒星在中心形成并非嵌埋星团质量分层现象的唯一解释．此外，气体的动力学摩擦能有效地减小动力学质量分层的时标，从而增大暂态质量分层的概率．

英文摘要：

The initial condition of massive star formation is still a mystery. Especially, it is a matter of dispute whether massive stars are formed in the center of embedded clusters. In view of the short time-scale of embedded clusters, some people argue that mass segregation in embedded clusters serves as the key evidence that massive stars are formed in the center. We use Monte Carlo method to investigate the evolution of embedded clusters. Initially, all stars are distributed as n o〈 r-2. We find that, during their dynamical evolu- tion, many clusters will present temporary mass segregation because of the random motion of massive stars. Some of them show quite apparent mass segregation that is possible to be observed. This result suggests that mass segregation does not necessarily mean that massive stars form in the center of embedded clusters. Dynamical friction can effectively shorten the time-scale of mass segregation and increase the probability of temporary mass segregation in a certain period.