The presence of a planetary magnetic field is an important ingredient for habitability. The coexistence of a solid and a liquid core can facilitate the maintenance of a compositionally driven dynamo; however, the likelihood of such a configuration in super‐Earths is unknown. Recently, shock experiments and ab initio calculations have constrained the stability, equations of state, and melting properties of ultrahigh pressure core and mantle phases. Here, we investigate the internal structure of super‐Earth exoplanets with a range of total masses and core mass fractions ranging from that of Mars (0.2) to Mercury (0.68), including an Earth‐like bulk composition. We examine the effect of the initial core‐mantle boundary temperature (T_CMB) on their internal structure and identify regimes with coexisting solid and liquid cores, and deep mantle melting. We find that the range of T_CMB for which an inner core is growing increases with the total planet mass and even more with the core mass fraction. Therefore, our results suggest that super‐Earths should have a crystallizing core over a large temperature range. We also find that the presence of a growing inner core is likely to be accompanied by a partially liquid lower mantle, which will likely influence planetary thermal evolution. We estimate the initial CMB temperature after super‐Earth accretion by assuming an accretional heat retention efficiency similar to Earth. We find that massive super‐Earths are expected to have an initial internal temperature consistent with a partially liquid core, allowing for the possibility of thermal and compositional dynamo action.

中文翻译：

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超地球内部结构和初始热态

行星磁场的存在是适居性的重要因素。固体核和液体核的共存可以促进组成驱动的发电机的维持。但是，在超级地球中进行这种配置的可能性尚不清楚。最近，冲击试验和从头算计算已经限制了超高压岩心和地幔相的稳定性，状态方程和熔融特性。在这里，我们研究了超地球系外行星的内部结构，其总质量和核心质量分数的范围从火星（0.2）到水星（0.68）在内，包括类地球的总体成分。我们研究了初始地幔边界温度（T _CMB）的内部结构，并确定具有固态和液态核心并存的地幔融化机制。我们发现T _CMB的范围内核的成长随着行星的总质量的增加而增加，而随核心质量的分数的增加甚至更多。因此，我们的结果表明，超级地球应该在较大的温度范围内具有结晶核。我们还发现，不断增长的内核的存在可能伴随着部分液态的下地幔，这很可能会影响行星的热演化。我们通过假设与地球相似的增加的保热效率来估算超地球增加后的初始CMB温度。我们发现，预计大型超级地球的初始内部温度与部分液态核保持一致，从而有可能发生热力作用和成分作用。