SIRIUS project. III. Star-by-star simulations of star cluster formation using a direct <i> <b>N</b> </i>-body integrator with stellar feedback
SIRIUS project. III. Star-by-star simulations of star cluster formation using a direct <i> <b>N</b> </i>-body integrator with stellar feedback
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天狼星项目。
DOI：
10.1093/pasj/psab061
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发表时间：
2021
影响因子：
2.3
通讯作者：
Wang Long
中科院分区：
文献类型：
--
作者：
Fujii Michiko S;Saitoh Takayuki R;Hirai Yutaka;Wang Long
星团形成模拟的计算挑战之一是解析单个恒星并模拟质量超过104M⊙的大质量星团，而不存在重力软化。结合直接体代码和光滑粒子流体动力学（SPH）代码，我们开发了一个新的代码，ASURA+BRIDGE，我们可以在不软化的情况下整合恒星粒子。我们在此代码中添加了Hiiregions的反馈模型，其中在Strömgren半径内给出了热和动量反馈。我们进行了星团形成的n -body/SPH模拟。在没有软化的情况下，一部分大质量恒星会从形成的星团中喷射出来。因此，恒星反馈作用于星团之外。这增强/抑制了最初亚病毒/超级病毒云中恒星的形成。我们发现形成的星团比目前观测到的疏散星团密度大，但质量-密度关系与估计的初始星团密度一致甚至更高。我们还发现，由于它们的分层结构，一些星团的恒星年龄分布有多个峰值。不考虑分子云的维里比，大约三分之一的恒星在气体排出后仍留在星团中。
One of the computational challenges of cluster formation simulations is resolving individual stars and simulating massive clusters with masses of more than 104M⊙without gravitational softening. Combining a directN-body code with smoothed-particle hydrodynamics (SPH) code, we have developed a new code, ASURA+BRIDGE, in which we can integrate stellar particles without softening. We add a feedback model for Hiiregions into this code, in which thermal and momentum feedback is given within the Strömgren radius. We performN-body/SPH simulations of star cluster formation. Without softening, a portion of massive stars are ejected from the forming clusters. As a result, the stellar feedback works outside the clusters. This enhances/suppresses the star formation in initially sub-virial/super-virial clouds. We find that the formed star clusters are denser than currently observed open clusters, but the mass–density relation is consistent with or even higher than that which is estimated as an initial cluster density. We also find that some clusters have multiple peaks in their stellar age distribution as a consequence of their hierarchical formation. Irrespective of the virial ratio of molecular clouds, approximately one-third of stars remain in the star clusters after gas expulsion.