Convective mixing in distant and close-in giant planets,Astronomy & Astrophysics

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Convective mixing in distant and close-in giant planets
Astronomy & Astrophysics ( IF 5.4 ) Pub Date : 2024-12-13 , DOI: 10.1051/0004-6361/202451897
J. Polman, C. Mordasini

Recent structure models of Jupiter suggest the existence of an extended region in the deep interior with a high heavy element abundance, referred to as a dilute core. This finding has led to increased interest in modelling the formation and evolution processes with the goal of understanding how and under what circumstances such a structure is formed and retained, to in turn better understand the relation between atmospheric and bulk metallicity. We modelled the evolution of giant planets, varying various parameters relevant for the convective mixing process, such as the mixing length parameter and the size of the mesh, and parameters related to the general evolution, such as the orbital distance and the initial luminosity. We in particular studied hot Jupiters and find that the effect of bloating on the mixing process is small but can in some cases inhibit convective mixing by lowering the intrinsic luminosity for a given entropy. Semi-convection can significantly lower the extent of a dilute core if it is strong enough. We find that dilute cores are unable to persist for initial luminosities much higher than ~3 × 10^{3^{L_{J_{for a Jupiter-like planet for the initial heavy element profiles we studied. From this we conclude that, based on our model, it is unlikely that a large number of giant planets retain a dilute core throughout their evolution, although this is dependent on the assumptions and limitations of our method. Future work should focus on improving the link between formation and evolution models so that the mixing process is accurately modelled throughout a planet’s lifetime and on improving the understanding of how to model convection near radiative-convective boundaries.}}}}

中文翻译：

远处和近处巨行星的对流混合

最近的木星结构模型表明，在木星内部深处存在一个具有较高重元素丰度的扩展区域，称为稀核。这一发现导致人们对模拟形成和演化过程的兴趣增加，目的是了解这种结构是如何以及在什么情况下形成和保留的，从而更好地理解大气和体金属丰度之间的关系。我们模拟了巨行星的演化，改变了与对流混合过程相关的各种参数，例如混合长度参数和网格大小，以及与一般演化相关的参数，例如轨道距离和初始光度。我们特别研究了热木星，发现膨胀对混合过程的影响很小，但在某些情况下可以通过降低给定熵的固有光度来抑制对流混合。如果稀芯足够强，半对流可以显著降低稀芯的程度。我们发现，对于我们研究的初始重元素剖面，对于类似木星的行星来说，稀核无法在远高于 ~3 × 103 LJ 的初始光度下持续存在。由此我们得出结论，根据我们的模型，大量巨行星在其演化过程中不太可能保留稀释的核心，尽管这取决于我们方法的假设和局限性。未来的工作应侧重于改善形成和演化模型之间的联系，以便在行星的整个生命周期中准确模拟混合过程，并提高对如何模拟辐射对流边界附近对流的理解。