THERMOHALINE INSTABILITIES INSIDE STARS: A SYNTHETIC STUDY INCLUDING EXTERNAL TURBULENCE AND RADIATIVE LEVITATION
THERMOHALINE INSTABILITIES INSIDE STARS: A SYNTHETIC STUDY INCLUDING EXTERNAL TURBULENCE AND RADIATIVE LEVITATION
复制标题
恒星内部的热盐不稳定性：包括外部湍流和辐射悬浮的综合研究
DOI：
10.1088/0004-637x/753/1/49
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发表时间：
2012
期刊：
影响因子：
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通讯作者：
S. Th'eado
中科院分区：
文献类型：
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作者：
S. Vauclair;S. Th'eado
通过求解Boussinesq方程，在近似不可压缩的分层流体中，采用线性近似，导出了一个新的恒星热盐混合系数的表达式，其中包括辐射悬浮和外部湍流的影响。众所周知，单个元素的辐射悬浮可以导致它们在特定的恒星层中积累。在某些情况下，它可以对恒星结构产生重要影响。在这里，我们证实，这种积累是缓和的温盐对流由于所得的反μ梯度。我们推导出的新系数表明，辐射加速度对热盐不稳定性本身的影响很小。然而，在所有计算中必须检查这种影响。我们还证实，大的水平湍流的存在可以减少甚至抑制温盐对流。这些结果是重要的，因为它们涉及到恒星中重元素积累的所有情况。辐射扩散的计算必须重新考虑，以包括温盐对流及其后果。这可能是观察到的丰度总是小于纯原子扩散预测的基本原因之一。在任何情况下，这些过程都必须与旋转诱导的混合竞争，但由于它们的相互作用，这种竞争比以前认为的更复杂。
We have derived a new expression for the thermohaline mixing coefficient in stars, including the effects of radiative levitation and external turbulence, by solving Boussinesq equations in a nearly incompressible stratified fluid with a linear approximation. It is well known that radiative levitation of individual elements can lead to their accumulation in specific stellar layers. In some cases, it can induce important effects on the stellar structure. Here we confirm that this accumulation is moderated by thermohaline convection due to the resulting inverse μ-gradient. The new coefficient that we have derived shows that the effect of radiative accelerations on the thermohaline instability itself is small. This effect must however be checked in all computations. We also confirm that the presence of large horizontal turbulence can reduce or even suppress the thermohaline convection. These results are important as they concern all the cases of heavy element accumulation in stars. Computations of radiative diffusion must be revisited to include thermohaline convection and its consequences. It may be one of the basic reasons for the fact that the observed abundances are always smaller than those predicted by pure atomic diffusion. In any case, these processes have to compete with rotation-induced mixing, but this competition is more complex than previously thought due to their mutual interaction.