在驱动和衰减Turbulence存在下分子云核的动力学：与观测的比较
The Kinematics of Molecular Cloud Cores in the Presence of Driven and Decaying Turbulence: Comparisons with Observations
摘要：
在这项研究中，我们使用流体动力学，自引力自适应网格细化模拟研究星前和原恒星核心的形成和性质，比较湍流不断驱动和允许衰减的情况。我们在C $^{18}$ O $(2\to 1)$、NH $_3(1,1)$和N $_2$ H $^+(1\to 0)$线上对这些核心的观测进行建模，并从模拟观测中测量各个核心的线宽、周围气体的线宽以及核心之间的相对运动。其中一些分布在驱动和衰减运行中显着不同，使它们成为确定所观察到的恒星形成云中的湍流是驱动还是衰减的潜在诊断。比较我们的模拟与观察到的英仙座和$ρ$蛇夫座云的核心显示相当好的协议之间的观察和模拟的核心到核心的速度分散驱动和衰减的情况下。然而，我们发现，通过原恒星核心的线宽在这两个模拟是太大的观测相比。这种分歧对于衰减模拟来说无疑更糟，在衰减模拟中，核心在其中心显示出高度超音速的下降信号，这些信号向边缘减小，这种模式在观察到的区域中看不到。这一结果提供了一些支持使用驱动湍流的恒星形成的区域建模，但得出一个确切的结论驱动或衰减的湍流的相对优点将需要更完整的数据上一个更大的样本的云以及模拟，包括磁场，外流，和热反馈的原恒星。
英文摘要：
In this study we investigate the formation and properties of prestellar and protostellar cores using hydrodynamic, self-gravitating Adaptive Mesh Refinement simulations, comparing the cases where turbulence is continually driven and where it is allowed to decay. We model observations of these cores in the C$^{18}$O$(2\to 1)$, NH$_3(1,1)$, and N$_2$H$^+(1\to 0)$ lines, and from the simulated observations we measure the linewidths of individual cores, the linewidths of the surrounding gas, and the motions of the cores relative to one another. Some of these distributions are significantly different in the driven and decaying runs, making them potential diagnostics for determining whether the turbulence in observed star-forming clouds is driven or decaying. Comparing our simulations with observed cores in the Perseus and $ρ$ Ophiuchus clouds shows reasonably good agreement between the observed and simulated core-to-core velocity dispersions for both the driven and decaying cases. However, we find that the linewidths through protostellar cores in both simulations are too large compared to the observations. The disagreement is noticably worse for the decaying simulation, in which cores show highly supersonic infall signatures in their centers that decrease toward their edges, a pattern not seen in the observed regions. This result gives some support to the use of driven turbulence for modeling regions of star formation, but reaching a firm conclusion on the relative merits of driven or decaying turbulence will require more complete data on a larger sample of clouds as well as simulations that include magnetic fields, outflows, and thermal feedback from the protostars.
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