论文标题
过去的月球发电机由其内核的进动驱动
A past lunar dynamo thermally driven by the precession of its inner core
论文作者
论文摘要
卡西尼状态的平衡与月球的进攻相关，预测地幔，流体核心和固体内核心在不同角度上。我们介绍了与核心大通边界（CMB），$ q_ {cmb} $以及内部核心边界（ICB），$ q_ {icb} $相关的粘性摩擦的耗散估计值。我们专注于后者，并表明，前提是内核大于100 km，$ q_ {icb} $可能高达$ 10^{10} {10} -10^{11} $ W，对于大多数core范围的核心密度模型而言。这大于将流体芯保持在绝热状态所需的功率，因此，ICB的差分进动物释放的热量可以通过热对流来驱动过去的月球发电机。该发电机可以超过CMB进动的发电机，并且可能只有最近就关闭了。月球表面的磁场强度的估计值为几美元$ t，与3 ga后记录的月球古磁强度兼容。我们进一步表明，与内核相关的卡西尼态的过渡可能是由于Lunar Orbit的进化而发生的。与$ q_ {icb} $相关的热通量可以是几个mw m $^{ - 2} $的顺序，该顺序应减慢内部核心的生长，并包括在月球核心的热演化模型中。
The Cassini state equilibrium associated with the precession of the Moon predicts that the mantle, fluid core and solid inner core precess at different angles. We present estimates of the dissipation from viscous friction associated with the differential precession at the core-mantle boundary (CMB), $Q_{cmb}$, and at the inner core boundary (ICB), $Q_{icb}$, as a function of the evolving lunar orbit. We focus on the latter and show that, provided the inner core was larger than 100 km, $Q_{icb}$ may have been as high as $10^{10}-10^{11}$ W for most of the lunar history for a broad range of core density models. This is larger than the power required to maintain the fluid core in an adiabatic state, therefore the heat released by the differential precession at the ICB can drive a past lunar dynamo by thermal convection. This dynamo can outlive the dynamo from precession at the CMB and may have shutoff only relatively recently. Estimates of the magnetic field strength at the lunar surface are of the order of a few $μ$T, compatible with the lunar paleomagnetic intensities recorded after 3 Ga. We further show that it is possible that a transition of the Cassini state associated with the inner core may have occurred as a result of the evolution of the lunar orbit. The heat flux associated with $Q_{icb}$ can be of the order of a few mW m$^{-2}$, which should slow down inner core growth and be included in thermal evolution models of the lunar core.
