红巨星中的磁-热盐混合
Magneto-Thermohaline Mixing in Red Giants
摘要：
我们修改了磁浮力模型，最近被提出作为一种机制，额外的混合在低质量红巨星的辐射区。最重要的修正是我们对上升的磁通量环与其周围介质之间的热交换的计算。这将浮力上升时间增加了五个数量级，因此参与混合的磁通量环的数量必须相应地增加。另一方面，我们的修正模型利用了这样一个事实，即在附近的氢燃烧壳形成的环的平均分子量已被3 He燃烧减少。这大大增加了它们的热盐浮力（因此，减少了总环数），使其相当于由B_phi ~ 10 MG的冻结环向场产生的纯磁浮力。我们强调，一些环仍然需要保持凝聚力，而上升的环形场。此外，该场防止水平湍流扩散侵蚀环与其周围介质之间的μ对比度。我们建议，所需的环形磁场产生的辐射区的差分旋转，拉伸预先存在的极向场的旋转轴周围，和磁通量环形成的结果，其浮力相关的不稳定性。
英文摘要：
We revise a magnetic buoyancy model that has recently been proposed as a mechanism for extra mixing in the radiative zones of low-mass red giants. The most important revision is our accounting of the heat exchange between rising magnetic flux rings and their surrounding medium. This increases the buoyant rising time by five orders of magnitude, therefore the number of magnetic flux rings participating in the mixing has to be increased correspondingly. On the other hand, our revised model takes advantage of the fact that the mean molecular weight of the rings formed in the vicinity of the hydrogen burning shell has been reduced by 3He burning. This increases their thermohaline buoyancy (hence, decreases the total ring number) considerably, making it equivalent to the pure magnetic buoyancy produced by a frozen-in toroidal field with B_phi ~ 10 MG. We emphasize that some toroidal field is still needed for the rings to remain cohesive while rising. Besides, this field prevents the horizontal turbulent diffusion from eroding the mu contrast between the rings and their surrounding medium. We propose that the necessary toroidal magnetic field is generated by differential rotation of the radiative zone, that stretches a pre-existing poloidal field around the rotation axis, and that magnetic flux rings are formed as a result of its buoyancy-related instability.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
