Collapsing molecular clouds with tracer particles – I. What collapses?
Collapsing molecular clouds with tracer particles – I. What collapses?
复制标题
带有示踪粒子的塌缩分子云 — I. 什么塌缩？
DOI：
10.1093/mnras/stac2834
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发表时间：
2022
影响因子：
4.8
通讯作者：
Jimenez Vela, Luz L.
中科院分区：
文献类型：
--
作者：
Collins, David C.;Le, Dan;Jimenez Vela, Luz L.
要了解恒星从分子气体云中形成的过程，人们基本上需要知道两件事：什么气体坍缩，以及坍缩需要多长时间。我们通过在三个自引力湍流模拟中嵌入伪拉格朗日示踪粒子来解决这些问题。我们确定星前核心的崩溃结束时，并使用示踪粒子倒带的模拟，以确定每个核心在每个模拟开始时的原像气体。这是一系列论文中的第一篇，我们提出了这项技术，并研究了第一个问题：什么气体塌缩？对于原像气体att= 0，我们研究了一些数量的概率分布函数（PDF）的几个数量，速度的结构函数，几个长度尺度，体积填充分数，不同的原像之间的重叠，和分形维数的原像气体。解析描述被发现的密度和速度的原像气体的PDF。我们发现，一个核心的原像是大而稀疏的，我们表明，一个核心的气体来自许多湍流密度波动和一些速度波动。我们发现，二进制系统的原像重叠的分形方式。最后，我们使用的密度分布推导出一个新的预测的星星的形成率。
To understand the formation of stars from clouds of molecular gas, one essentially needs to know two things: what gas collapses, and how long it takes to do so. We address these questions by embedding pseudo-Lagrangian tracer particles in three simulations of self-gravitating turbulence. We identify prestellar cores at the end of the collapse, and use the tracer particles to rewind the simulations to identify the preimage gas for each core at the beginning of each simulation. This is the first of a series of papers, wherein we present the technique and examine the first question: What gas collapses? For the preimage gas att= 0, we examine a number of quantities – the probability distribution function (PDF) for several quantities, the structure function for velocity, several length scales, the volume filling fraction, the overlap between different preimages, and fractal dimension of the preimage gas. Analytical descriptions are found for the PDFs of density and velocity for the preimage gas. We find that the preimage of a core is large and sparse, and we show that gas for one core comes from many turbulent density fluctuations and a few velocity fluctuations. We find that binary systems have preimages that overlap in a fractal manner. Finally, we use the density distribution to derive a novel prediction of the star formation rate.