Cluster Formation in Protostellar Outflow-driven Turbulence
Cluster Formation in Protostellar Outflow-driven Turbulence
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DOI：
10.1086/503419
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发表时间：
2005-12
期刊：
影响因子：
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通讯作者：
Zhi-Yun Li;F. Nakamura
中科院分区：
文献类型：
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作者：
Zhi-Yun Li;F. Nakamura
大多数，也许是所有的恒星在形成过程中都会经历一个剧烈的外流阶段。我们研究，通过三维MHD模拟，原恒星外流对集群形成的影响。我们发现，在集群形成区域中的初始湍流很快被外流产生的运动所取代。原恒星外流驱动的湍流（简称“原恒星湍流”）可以在初始湍流衰减后很长时间内保持该区域接近维里平衡。我们认为，有两种类型的湍流在恒星形成的云：原始（或“星际”）湍流和原恒星湍流，前者转化为后者主要是在嵌入式集群，如NGC 1333。由于大多数恒星被认为是在星团中形成的，这意味着恒星的初始质量函数在很大程度上是由恒星本身决定的，通过外流，单独限制了形成恒星的质量吸积，并共同塑造了大多数星团成员形成的环境（密度结构和速度场）。我们推测，大规模的星团形成的团块支持的原恒星湍流逐渐演变成一个高度集中的“枢纽”状态，最终在快速形成的大质量恒星的致密部分通过吸积。
Most, perhaps all, stars go through a phase of vigorous outflow during formation. We examine, through three-dimensional MHD simulation, the effects of protostellar outflows on cluster formation. We find that the initial turbulence in the cluster-forming region is quickly replaced by motions generated by outflows. The protostellar outflow-driven turbulence ("protostellar turbulence" for short) can keep the region close to a virial equilibrium long after the initial turbulence has decayed away. We argue that there exist two types of turbulence in star-forming clouds: a primordial (or "interstellar") turbulence and a protostellar turbulence, with the former transformed into the latter mostly in embedded clusters such as NGC 1333. Since the majority of stars are thought to form in clusters, an implication is that the stellar initial mass function is determined to a large extent by the stars themselves, through outflows that individually limit the mass accretion onto forming stars and collectively shape the environments (density structure and velocity field) in which most cluster members form. We speculate that massive cluster-forming clumps supported by protostellar turbulence gradually evolve toward a highly centrally condensed "pivotal" state, culminating in rapid formation of massive stars in the densest part through accretion.