标题： 磁发电机触发的亚临界过渡到湍流 显示英文标题

标题： Subcritical transition to turbulence triggered by a magnetic dynamo

摘要： 最近的研究表明，许多恒星的显著减速可归因于辐射区内强磁场的出现，在此区域内，热量通过稳定分层层中的辐射传递。在这里，我们描述了如何将这一转变理解为线性稳定的流动中小尺度湍流的次临界分岔。这种湍流由非线性平均场发电机维持，并且可以观察到相对较小的差速旋转，远离任何流体力学不稳定性线性起始值。在此范围内，湍流波动提供了无扩散的角动量传输，增加了由触发湍流的磁场生成的传输。最后，我们提出一个简单的非线性模型，能够捕捉这一情景，并可用作天体物理流体湍流转捩的一般描述，只要它涉及大尺度发电机与小尺度磁场不稳定性之间的竞争。 显示英文摘要

摘要： It has recently been shown that a significant slowdown of many stars can be attributed to the emergence of a strong magnetic field within the radiative region, where heat is transferred through radiation in a stably stratified layer. Here, we describe how this transition can be understood as a subcritical bifurcation to small-scale turbulence in linearly stable flows. The turbulence is sustained by a nonlinear mean-field dynamo and can be observed down to relatively small differential rotation, arbitrarily far from the linear onset of any hydrodynamic instability. In this regime, turbulent fluctuations provide diffusivity-free transfer of angular momentum that increases the transport generated by the magnetic field triggering the turbulence. Finally, we present a simple nonlinear model that captures this scenario and can be used as a general description of the transition to turbulence in astrophysical flows, as long as it involves a competition between a large-scale dynamo, and a small-scale magnetic instability.