Stellar and substellar initial mass function: a model that implements gravoturbulent fragmentation and accretion
Stellar and substellar initial mass function: a model that implements gravoturbulent fragmentation and accretion
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DOI：
10.1111/j.1365-2966.2010.17681.x
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发表时间：
2010-10
影响因子：
4.8
通讯作者：
T. Veltchev;R. Klessen;P. Clark
中科院分区：
文献类型：
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作者：
T. Veltchev;R. Klessen;P. Clark
在这项工作中，我们从致密核的质量分布叠加得到恒星初始质量函数(IMF)，致密核是通过分子云(MC)中不稳定团块的重力湍流碎裂而产生的，并通过竞争吸积而增长。MCS是由星际介质中的湍流级联形成的，尺度从L 100pc到∼0.1pc。它们的内部湍流本质上是超音速的，并产生密度为对数正态分布的团块。我们的模型基于团团质量和团块密度之间的幂函数关系的假设：N∝Mx，其中x是无标度参数。引力不稳定的团块被假定经历等温碎裂，并产生质量呈对数正态分布的原恒星核心，中心位于团块Jeans质量周围。然后，假设单个岩心的质量会通过竞争吸积进一步增长，直到团块内的其余气体耗尽。当选择x=0.25时，特征恒星形成时间尺度为∼5Myr，低恒星形成效率为∼10%时，观测到的国际货币基金组织是最好的再现。
In this work, we derive the stellar initial mass function (IMF) from the superposition of mass distributions of dense cores, generated through gravoturbulent fragmentation of unstable clumps in molecular clouds (MCs) and growing through competitive accretion. MCs are formed by the turbulent cascade in the interstellar medium at scales L from 100 down to ∼0.1 pc. Their internal turbulence is essentially supersonic and creates clumps with a lognormal distribution of densities n. Our model is based on the assumption of a power-law relationship between clump mass and clump density: n∝mx, where x is a scale-free parameter. Gravitationally unstable clumps are assumed to undergo isothermal fragmentation and produce protostellar cores with a lognormal mass distribution, centred around the clump Jeans mass. Masses of individual cores are then assumed to grow further through competitive accretion until the rest of the gas within the clump is being exhausted. The observed IMF is best reproduced for a choice of x= 0.25, for a characteristic star formation time-scale of ∼5 Myr and for a low star formation efficiency of ∼10 per cent.