论文标题

在类似太阳能恒星的模拟中进行物理动机的热传导处理:对发电机过渡的影响

Physically motivated heat conduction treatment in simulations of solar-like stars: effects on dynamo transitions

论文作者

Viviani, M., Käpylä, M. J.

论文摘要

语境。在许多方面的观察结果与观察结果不一致:它们在大尺寸的动力频谱中显示出盈余的能量,抗 - 极性差异旋转曲线具有加速度的抗差速器和慢速转移速度,它们的转移速度与非转移率相比。即使模拟在快速旋转器中重现了观察到的活动纵向,但它们在旋转框架中的运动(所谓的方位角发动机波,ADW)还是逆行的,与观测中普遍存在的前列运动相反。目标。我们研究了更现实的热传导率治疗在减轻观察和模拟之间差异的影响。方法。我们通过将Kramers不透明度定律应用于描述类似太阳能恒星的对流信封的半全球球形设置,而不是通过混合长度参数的规定的热传导曲线来使用物理动机的热传导。结果。我们发现,结果的某些方面现在更好地对应于观察结果:轴至非轴对称过渡点朝着较高的旋转速率转移。我们还发现ADWS的传播方向发生了变化,因此现在也发现了前进波。然而,从反 - 极性旋转曲线到太阳能旋转曲线的过渡也向更高的旋转速率转移,使模型成为更不切实际的机制。结论。尽管基于Kramers的热传导无助于再现太阳旋转曲线,但它确实有助于更快的旋转状态,在此旋转方案中,Dynamo解决方案现在与观察结果更好。

Context. Results from global magnetoconvection simulations of solar-like stars are at odds with observations in many respects: They show a surplus of energy in the kinetic power spectrum at large scales, anti-solar differential rotation profiles, with accelerated poles and a slow equator, for the solar rotation rate, and a transition from axi- to non-axisymmetric dynamos at a much lower rotation rate than what is observed. Even though the simulations reproduce the observed active longitudes in fast rotators, their motion in the rotational frame (the so-called azimuthal dynamo wave, ADW) is retrograde, in contrast to the prevalent prograde motion in observations. Aims. We study the effect of a more realistic treatment of heat conductivity in alleviating the discrepancies between observations and simulations. Methods. We use physically-motivated heat conduction, by applying Kramers opacity law, on a semi-global spherical setup describing convective envelopes of solar-like stars, instead of a prescribed heat conduction profile from mixing-length arguments. Results. We find that some aspects of the results now better correspond to observations: The axi- to non-axisymmetric transition point is shifted towards higher rotation rates. We also find a change in the propagation direction of ADWs so that also prograde waves are now found. The transition from anti-solar to solar-like rotation profile, however, is also shifted towards higher rotation rates, leaving the models into an even more unrealistic regime. Conclusions. Although a Kramers-based heat conduction does not help in reproducing the solar rotation profile, it does help in the faster rotation regime, where the dynamo solutions now match better with observations.

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