Turbulent action at a distance due to stellar feedback in magnetized clouds
Turbulent action at a distance due to stellar feedback in magnetized clouds
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DOI：
10.1038/s41550-018-0566-1
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发表时间：
2018-09
期刊：
影响因子：
14.1
通讯作者：
S. Offner;Yue Liu
中科院分区：
文献类型：
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作者：
S. Offner;Yue Liu
分子云的一个基本特性是它们是湍流的，但是这种湍流是如何产生和维持的还不清楚。一种可能性是，在云内形成的恒星通过它们的流出物、风和辐射（“反馈”）重新产生湍流。然而，解开由最初的云湍流反馈产生的纠缠运动是具有挑战性的。在这里，我们通过识别和分离恒星风的局部和全球影响来面对恒星反馈和湍流之间的关系。我们分析磁流体动力学模拟，跟踪风物质与周围云的相互作用。通过区分发射物质、风携带的气体和原始气体，我们发现能量是通过膨胀的风壳激发的电磁波从源头转移出去的。与压缩运动相比，这种作用在一定距离上提高了搅拌运动的比例，并产生了更平坦的速度功率谱。我们得出的结论是，恒星反馈解释了分子云内重要的能量转移——电磁波增强了这种影响，而这种影响以前被观测忽略了。总体而言，恒星反馈可以部分抵消全球湍流耗散。
A fundamental property of molecular clouds is that they are turbulent, but how this turbulence is generated and maintained is unknown. One possibility is that stars forming within the cloud regenerate turbulence via their outflows, winds and radiation (‘feedback’). However, disentangling motions created by feedback from the initial cloud turbulence is challenging. Here, we confront the relationship between stellar feedback and turbulence by identifying and separating the local and global impact of stellar winds. We analyse magnetohydrodynamic simulations in which we track wind material as it interacts with the ambient cloud. By distinguishing between launched material, gas entrained by the wind and pristine gas we show energy is transferred away from the sources via magnetic waves excited by the expanding wind shells. This action at a distance enhances the fraction of stirring motion compared with compressing motion and produces a flatter velocity power spectrum. We conclude that stellar feedback accounts for significant energy transfer within molecular clouds—an impact enhanced by magnetic waves, which have previously been neglected by observations. Overall, stellar feedback can partially offset global turbulence dissipation.