FEEDBACK EFFECTS ON LOW-MASS STAR FORMATION
FEEDBACK EFFECTS ON LOW-MASS STAR FORMATION
复制标题
对低质量恒星形成的反馈效应
DOI：
10.1088/0004-637x/747/1/22
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发表时间：
2012
期刊：
影响因子：
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通讯作者：
R. Fisher
中科院分区：
文献类型：
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作者：
Charles E. Hansen;R. Klein;C. McKee;R. Fisher
原恒星的反馈，辐射和双极流出，显着影响的碎片和质量吸积从恒星形成的核心。我们使用ORION，一个自适应网格细化重力辐射流体动力学代码，模拟低质量星星形成的湍流分子云中存在的原恒星反馈。我们提出的第一个模拟的恒星形成集群，包括辐射传输和原恒星外流的结果。我们运行了四个模拟，以隔离辐射反馈和流出反馈的单独影响以及两者的组合。我们发现，外流减少原恒星的质量和吸积率分别由三个因素，因此减少原恒星的光度由一个数量级。这意味着，虽然辐射反馈抑制碎片，流出使原恒星辐射在很大程度上无关的低质量星星形成以上的质量标度为0.05 M。我们发现我们的云的初始碎片是全球牛仔裤长度的一半，大约0.1pc。由于没有足够的原恒星辐射来阻止它，这些0.1pc的核心不断分裂，通常每个核心形成10颗恒星。在这些恒星的吸积率与质量的规模从核心吸积模型，包括热和湍流运动的预测，吸积率似乎并不符合无论是竞争性吸积或吸积从等温球。我们发现，原恒星外流并没有显着影响整体云动力学，在磁场的情况下，由于其小的开度角和不良的耦合致密气体。流出物使核心的质量减少2/3，使核心达到星星效率，使核心的质量减少1/3。模拟还能够再现许多对局部恒星形成区域的观测。我们的模拟与辐射和外流再现所观察到的原恒星光度函数。所有的模拟都能再现观测到的核心质量函数，尽管我们发现它们对望远镜分辨率很敏感。我们还重现了这些观察到的核心的两点相关函数。最后，我们重现初始质量函数本身，包括低质量端，当流出。
Protostellar feedback, both radiation and bipolar outflows, dramatically affects the fragmentation and mass accretion from star-forming cores. We use ORION, an adaptive mesh refinement gravito-radiation-hydrodynamics code, to simulate low-mass star formation in a turbulent molecular cloud in the presence of protostellar feedback. We present results of the first simulations of a star-forming cluster that include both radiative transfer and protostellar outflows. We run four simulations to isolate the individual effects of radiation feedback and outflow feedback as well as the combination of the two. We find that outflows reduce protostellar masses and accretion rates each by a factor of three and therefore reduce protostellar luminosities by an order of magnitude. This means that, while radiation feedback suppresses fragmentation, outflows render protostellar radiation largely irrelevant for low-mass star formation above a mass scale of 0.05 M☉. We find initial fragmentation of our cloud at half the global Jeans length, around 0.1 pc. With insufficient protostellar radiation to stop it, these 0.1 pc cores fragment repeatedly, forming typically 10 stars each. The accretion rate in these stars scales with mass as predicted from core accretion models that include both thermal and turbulent motions; the accretion rate does not appear to be consistent with either competitive accretion or accretion from an isothermal sphere. We find that protostellar outflows do not significantly affect the overall cloud dynamics, in the absence of magnetic fields, due to their small opening angles and poor coupling to the dense gas. The outflows reduce the mass from the cores by 2/3, giving a core to star efficiency, ϵcore ≃ 1/3. The simulations are also able to reproduce many observation of local star-forming regions. Our simulation with radiation and outflows reproduces the observed protostellar luminosity function. All of the simulations can reproduce observed core mass functions, though we find they are sensitive to telescope resolution. We also reproduce the two-point correlation function of these observed cores. Lastly, we reproduce the initial mass function itself, including the low-mass end, when outflows are included.