Differential rotation and convection in the Sun
Differential rotation and convection in the Sun
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DOI：
10.1111/j.1365-2966.2009.15464.x
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发表时间：
2009-07
影响因子：
4.8
通讯作者：
S. Balbus;S. Balbus;Julius Bonart;H. Latter;N. Weiss
中科院分区：
文献类型：
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作者：
S. Balbus;S. Balbus;Julius Bonart;H. Latter;N. Weiss
我们表明，太阳对流区的差分旋转轮廓，除了内部和外部边界层，可以再现具有很高的精度，如果isorotation轮廓对应的热成风方程的特性。这就要求有一个涉及熵和角速度的正式的定量关系。早期的工作表明，这可能会产生磁流体动力学的稳定性约束，在这里，我们认为，纯粹的流体动力学过程也可能导致这样的结果。对于流体动力学解特别重要的是，热风方程对径向熵梯度不敏感。这使得一个更一般的解决方案，以适应太阳等自转轮廓，而不仅仅是那些熵本身必须是角速度的函数。特别是，对于这个扩展类，即使存在大的径向熵梯度，太阳自转廓线的热成风解仍然有效。这类解决方案的一个明确和明确的例子似乎是目前在出版的太阳对流区的数值模拟。虽然该理论是流体力学性质的，但对弱磁场的存在并不敏感。因此，识别太阳等自转线的热风方程的特点似乎是强大的，适应，但绝不要求，磁场动力学。
We show that the differential rotation profile of the solar convection zone, apart from inner and outer boundary layers, can be reproduced with great accuracy if the isorotation contours correspond to characteristics of the thermal wind equation. This requires that there be a formal quantitative relationship involving the entropy and the angular velocity. Earlier work has suggested that this could arise from magnetohydrodynamic stability constraints; here, we argue that purely hydrodynamical processes could also lead to such a result. Of special importance to the hydrodynamical solution is the fact that the thermal wind equation is insensitive to radial entropy gradients. This allows a much more general class of solutions to fit the solar isorotation contours, beyond just those in which the entropy itself must be a function of the angular velocity. In particular, for this expanded class, the thermal wind solution of the solar rotation profile remains valid even when large radial entropy gradients are present. A clear and explicit example of this class of solution appears to be present in published numerical simulations of the solar convective zone. Though hydrodynamical in character, the theory is not sensitive to the presence of weak magnetic fields. Thus, the identification of solar isorotation contours with the characteristics of the thermal wind equation appears to be robust, accommodating, but by no means requiring, magnetic field dynamics.