孤立和多重星前系统中星前盘的性质
The Properties of Prestellar Discs in Isolated and Multiple Prestellar Systems
摘要：
我们提出了高分辨率的三维光滑粒子流体动力学模拟的形成和演化的原恒星盘在湍流分子云。使用分段多方状态方程，我们进行了两组模拟。在这两种情况下，我们发现，孤立系经历了一个根本不同的演化比二元或多元系统的成员。当形成时，孤立系必须增加质量并增加其特定的角动量，导致形成大质量的扩展盘，这些盘经历强烈的引力不稳定性并容易受到盘碎片的影响。在我们的模拟中产生了初始质量为5.5 Mjup，7.4 Mjup和12 Mjup的碎片。在双星和小星系团，我们观察到，由于从母核的材料竞争，成员不吸积显着数量的高比角动量气体相对于孤立系。我们发现，在多个系统中的光盘是强烈的自引力，但他们是稳定的，对碎片由于光盘截断和质量剖面陡峭的潮汐，吸积高比角动量气体的其他成员，和角动量被重定向到成员的轨道。一般来说，我们预计磁盘碎片不太可能在集群和更多的孤立系的功能。
英文摘要：
We present high-resolution 3D smoothed particle hydrodynamics simulations of the formation and evolution of protostellar discs in a turbulent molecular cloud. Using a piecewise polytropic equation of state, we perform two sets of simulations. In both cases we find that isolated systems undergo a fundamentally different evolution than members of binary or multiple systems. When formed, isolated systems must accrete mass and increase their specific angular momentum, leading to the formation of massive, extended discs, which undergo strong gravitational instabilities and are susceptible to disc fragmentation. Fragments with initial masses of 5.5 M_jup, 7.4 M_jup and 12 M_jup are produced in our simulations. In binaries and small clusters, we observe that due to competition for material from the parent core, members do not accrete significant amounts of high specific angular momentum gas relative to isolated systems. We find that discs in multiple systems are strongly self-gravitating but that they are stable against fragmentation due to disc truncation and mass profile steeping by tides, accretion of high specific angular momentum gas by other members, and angular momentum being redirected into members' orbits. In general, we expect disc fragmentation to be less likely in clusters and to be more a feature of isolated systems.
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