论文标题
岩石行星的热演化和磁历史
Thermal Evolution and magnetic history of rocky planets
论文作者
论文摘要
我们提出了一个热进化模型，再加上Henyey求解器，以研究岩石行星可能在其液态铁芯和/或岩浆海洋中托管发电机的情况。我们通过求解地幔和核心的能量平衡方程来计算行星热轮廓的演变。我们使用改进的混合长度理论来对岩浆海洋和固体地幔中的对流热流进行建模。此外，通过包括Henyey求解器，我们自言自语解释了由于行星收缩（扩展）而引起的内部结构和加热（冷却）的调整。我们评估发电机是否可以使用临界磁性雷诺数进行操作。我们运行模拟以探索行星质量（$ M_ {PL} $），核心质量分数（CMF）和平衡温度（$ t_ {eq} $）如何影响可能的发电机来源的演变和寿命。我们发现$ t_ {eq} $决定了岩浆海洋的凝固状态，并且只有熔体分数大于临界值的层层可能有助于岩浆海洋中的发电机区域。我们发现由$ M_ {PL} $和CMF确定的地幔质量控制对铁芯的热隔离效果。此外，我们表明，随着行星质量的增加，液态芯的使用寿命更长。对于40 $ \\ MATHRM {wm^{ - 1} k^{ - 1}} $的核心热导率，铁芯中的发电机的寿命受到液体核心的寿命限制，因为液体核心的寿命为1 $ m _ {\ oplus} $ planets，并且由于缺乏3 $ m _ $ m _ _ = $ m _ = = $ oplus的热对流。
We present a thermal evolution model coupled with a Henyey solver to study the circumstances under which a rocky planet could potentially host a dynamo in its liquid iron core and/or magma ocean. We calculate the evolution of planet thermal profiles by solving the energy balance equations for both the mantle and the core. We use a modified mixing length theory to model the convective heat flow in both the magma ocean and solid mantle. In addition, by including the Henyey solver, we self-consistently account for adjustments in the interior structure and heating (cooling) due to planet contraction (expansion). We evaluate whether a dynamo can operate using the critical magnetic Reynolds number. We run simulations to explore how planet mass ($M_{pl}$), core mass fraction (CMF) and equilibrium temperature ($T_{eq}$) affect the evolution and lifetime of possible dynamo sources. We find that the $T_{eq}$ determines the solidification regime of the magma ocean, and only layers with melt fraction greater than a critical value of 0.4 may contribute to the dynamo source region in the magma ocean. We find that the mantle mass, determined by $M_{pl}$ and CMF, controls the thermal isolating effect on the iron core. In addition, we show that the liquid core last longer with increasing planet mass. For a core thermal conductivity of 40$\ \mathrm{Wm^{-1}K^{-1}}$, the lifetime of the dynamo in the iron core is limited by the lifetime of the liquid core for 1$M_{\oplus}$ planets, and by the lack of thermal convection for 3$M_{\oplus}$ planets.
