论文标题
质量有限的非常年轻的恒星簇中最庞大的恒星：证据有利于恒星形成过程中的显着自我调节
The most massive stars in very young star clusters with a limited mass: Evidence favours significant self-regulation in the star formation processes
论文作者
论文摘要
恒星初始质量函数（IMF）通常被解释为一种比例不变的概率密度分布函数（PDF），因此许多小簇产生的IMF与一个相同数量的恒星相同的IMF。对全球范围内的IMF的观察挑战了这一点，因为矮星系并不像预期的那样多大的恒星。这表明一个高度自我调节的恒星形成过程，其中恒星质量不是从IMF中随机取样的，而与恒星形成的环境有关。在这里，使用恒星集群中最大的恒星与其父母恒星群集质量（$ m _ {\ rm max} $ - $ m _ {\ rm ecl} $关系）。如果从IMF随机采样恒星，则认为这种关系是一种统计效应。通过比较观察到的$ m _ {\ rm max} $ - $ m _ {\ rm ecl} $与合成星形群集和随随机取样的恒星群众的分布，我们发现模拟观察的预期分散比观察到的分散分散。假设$ m _ {\ rm max} $和$ m _ {\ rm ecl} $不确定性是正确的，那么我们的测试拒绝了以下假设：IMF是PDF，pdf是PDF的$4.5σ$置信度。另外，我们提供了一个确定性的恒星质量抽样工具，该工具可复制观察到的$ M _ {\ rm max} $ - $ m _ {\ rm ecl} $分布，并与恒星形成分子团的亮度进行了很好的比较。此外，我们发现$ m _ {\ rm max} $ - $ m _ {\ rm ecl} $关系有显着的扁平化。这可能表明，明星的强烈反馈比$ 13〜m_ \ odot $和/或从质量范围63到$ 400〜m_ \ odot $中的最大恒星弹出可能是形成簇的重要物理过程。
The stellar initial mass function (IMF) is commonly interpreted to be a scale-invariant probability density distribution function (PDF) such that many small clusters yield the same IMF as one massive cluster of the same combined number of stars. Observations of the galaxy-wide IMF challenge this as dwarf galaxies do not form as many massive stars as expected. This indicates a highly self-regulated star formation process in which stellar masses are not stochastically sampled from the IMF and are instead related to the environment of star formation. Here, the nature of star formation is studied using the relation between the most massive star born in a star cluster and its parental stellar cluster mass (the $m_{\rm max}$--$M_{\rm ecl}$ relation). This relation has been argued to be a statistical effect if stars are sampled randomly from the IMF. By comparing the tightness of the observed $m_{\rm max}$--$M_{\rm ecl}$ distribution with synthetic star clusters with stochastically sampled stellar masses, we find that the expected dispersion of the mock observations is much larger than the observed dispersion. Assuming that $m_{\rm max}$ and $M_{\rm ecl}$ uncertainties from the literature are correct, our test rejects the hypothesis that the IMF is a PDF at a more than $4.5σ$ confidence level. Alternatively, we provide a deterministic stellar mass sampling tool which reproduces the observed $m_{\rm max}$--$M_{\rm ecl}$ distribution and compares well with the luminosities of star-forming molecular clumps. In addition, we find that there is a significant flattening of the $m_{\rm max}$--$M_{\rm ecl}$ relation near $m_{\rm max}=13~M_\odot$. This may suggest strong feedback of stars more massive than about $13~M_\odot$ and/or the ejections of the most massive stars from young clusters in the mass range 63 to $400~M_\odot$ to be likely important physical processes in forming clusters.
