Updated formation and structure models of Jupiter predict a metal-poor envelope. This is at odds with the two to three times solar metallicity measured by the Galileo probe. Additionally, Juno data imply that water and ammonia are enriched. Here, we explore whether Jupiter could have a deep radiative layer separating the atmosphere from the deeper interior. The radiative layer could be caused by a hydrogen-transparency window or depletion of alkali metals. We show that heavy-element accretion during Jupiter’s evolution could lead to the desired atmospheric enrichment and that this configuration would be stable over billions of years. The origin of the heavy elements could be cumulative small impacts or one large impact. The preferred scenario requires a deep radiative zone, due to a local reduction of the opacity at ∼2000 K by ∼90%, which is supported by Juno data, and vertical mixing through the boundary with an efficiency similar to that of molecular diffusion (D ≲ 10⁻² cm² s⁻¹). Therefore, most of Jupiter’s molecular envelope could have solar composition while its uppermost atmosphere is enriched with heavier elements. The enrichment likely originates from the accretion of solid objects. This possibility resolves the long-standing mismatch between Jupiter’s interior models and atmospheric composition measurements. Furthermore, our results imply that the measured atmospheric composition of exoplanets does not necessarily reflect their bulk compositions. We also investigate whether the enrichment could be due to the erosion of a dilute core and show that this is highly unlikely. The core-erosion scenario is inconsistent with evolution calculations, the deep radiative layer, and published interior models.

中文翻译：

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木星的大气金属丰度与深层内部不同吗？


更新的木星形成和结构模型预测了一个贫金属包层。这与伽利略探测器测量到的两到三倍太阳金属丰度不一致。此外，朱诺号数据表明水和氨被富集。在这里，我们探索木星是否可能有一个深层辐射层将大气与更深层的内部分开。辐射层可能是由氢透明窗口或碱金属耗尽引起的。我们表明，木星演化过程中的重元素吸积可能会导致所需的大气富集，并且这种结构将在数十亿年内保持稳定。重元素的来源可能是累积的小影响或一次大影响。优选的方案需要深辐射区，因为在~2000 K时不透明度局部降低~90%，这得到了朱诺数据的支持，并且通过边界的垂直混合效率类似于分子扩散（D ≲ 10 ⁻² 厘米 ² 秒 ⁻¹ ）。因此，木星的大部分分子包膜可能含有太阳成分，而其最上层大气则富含较重元素。浓缩可能源于固体物体的吸积。这种可能性解决了木星内部模型和大气成分测量之间长期存在的不匹配问题。此外，我们的结果表明，测量的系外行星大气成分不一定反映其整体成分。我们还调查了富集是否可能是由于稀释核心的侵蚀造成的，并表明这种可能性极小。核心侵蚀情景与演化计算、深层辐射层和已发布的内部模型不一致。