AFFIRM MASS - Accretion Flows and Feedback In Realistic Models of MASsive Star formation

背景：大质量恒星的形成——特别是在质量上限——预计会受到恒星反馈的影响，甚至受到辐射力和光电离形式的控制。但是数值模拟只在非常罕见的情况下覆盖了bbb100 M⊙区域，并且主要针对原始和现在的恒星形成情况探索了大质量恒星反馈的金属丰度依赖性，而没有对这两种极端情况之间的参数空间进行彻底扫描。方法：为了对大质量恒星的反馈进行模拟，我们将利用我们最近开发的数值框架。这个恒星形成代码是一个独特的工具，因为它能够同时考虑到原恒星流出、辐射力和光电离反馈（以及恒星演化和尘埃演化）。目的：我们提出研究这些反馈效应及其相互作用对形成吸积盘-流出系统的影响，在多物理场数值模型中，从亚au区域的大质量恒星前核心坍缩到大质量恒星形成的最显著特征，即原恒星流出和HII区域。我们将在恒星质量上限范围内确定恒星前核坍缩的恒星形成效率，包括其对金属丰度的依赖。基于分析论证，我们期望从低金属丰度（早期宇宙）的主导光电离反馈过渡到高金属丰度（当前情况）的主导辐射力。我们将通过定量地确定恒星质量上限范围内的反馈效率来测试这些分析驱动的假设。r<s:1>萨姆斯：我们将利用研究小组提出的第6年扩展来研究恒星质量上限制度下的辐射力和光电离反馈，并确定它们对金属丰度的依赖。特别着重于从当前情况下的主导辐射力到原始恒星形成情况下的主导光电离反馈的转变。除了这些直接的任务之外，目前正在进行的项目的后续任务包括将我们最近的数值模型与观测到的磁盘碎片和恒星多样性进行比较，将已经部署的代码的磁流体动力学能力合并到我们的恒星反馈框架中，以及将已经部署的热解离和氢电离模块合并到我们的恒星反馈框架中。

Context: Massive star formation – especially at the upper mass limit – is expected to be influenced or even controlled by stellar feedback in form of radiation forces and photoionization. But numerical simulations have covered the > 100 M⊙ regime only in very rare cases and the metallicity dependence of massive star feedback has been explored mainly for the primordial and present-day star formation case without a thorough scan of the parameter space in between these two extreme cases.Methods: In order to perform simulations of stellar feedback in the regime of the most massive stars, we will utilize our recently developed numerical framework. This star formation code denotes a unique tool in the sense that it is capable of taking into account protostellar outflows, radiation forces, and photoionization feedback simultaneously (along with stellar evolution and dust evolution).Aims: We propose to study the impact of these feedback effects and their interplay onto the forming accretion disk – outflow system in multi-physics numerical models of the collapse of massive pre-stellar cores from the sub-AU regime up to the most distinctive features of high-mass star formation, namely protostellar outflows and HII regions. We will determine the star formation efficiency of the pre-stellar core collapse in the regime of the upper mass limit of stars including its dependence on metallicity.Based on analytical arguments, we expect a transition from dominating photoionization feedback in the regime of low metallicities (early universe) to dominating radiation forces for higher metallicities (present-day case). We will test these analytically motivated hypotheses by quantitatively determining the feedback efficiencies in the regime of the upper mass limit of stars.Résumé: We will use the proposed 6th year extension of the research group to investigate radiation forces and photoionization feedback in the regime of the upper mass limit of stars and determine their metallicity dependence. Special focus is given on the transition from the regime of dominating radiation forces in the present-day case to the regime of dominating photoionization feedback in the primordial star formation case.Additionally to these straight-forward tasks, follow-up tasks of the currently ongoing projects include comparison of our recent numerical models to observations of disk fragmentation and stellar multiplicity, the merging of the already deployed magneto-hydrodynamics capabilities of the code into our stellar feedback framework, and the merging of the already deployed module for thermal dissociation and ionization of hydrogen into our stellar feedback framework.