论文标题
EDECONTION共振/准共振的潮汐演变和Earth-Moon系统的角动量
Tidal Evolution of the Evection Resonance/Quasi-Resonance and the Angular Momentum of the Earth-Moon System
论文作者
论文摘要
通过高角度动量影响形成月球可以解释地球同位素的相似性,但是,在月球形成后,需要将影响后的角动量降低2倍以上2或更多。当月球围角序期等于一年时,会捕获到ED EXECTION共鸣中,可以消除角动量过量。但是,适当的角动量去除似乎对潮汐模型和选择的潮汐参数敏感。在这项工作中,我们使用恒定的时延迟潮汐模型来探索月球的轨道演变。我们发现,正式驱动的退出发生在早期,随后,月亮进入准谐振机制,即使谐振角不再列出,Exection仍然可以调节月球偏心率。尽管不适合共振,但在准共振期间,角动量将连续从地球系统中移除,并转移到地球的地中心轨道上。最终的角动量是由准共和度逃逸时间设定的,是月球和地球潮汐强度之比的函数,以及地球中潮汐消散的绝对速率。当地幔从熔融到部分熔融状态的地幔冷却时,我们考虑了地球潮汐消散的物理动机模型。我们发现,随着地幔的巩固,陆地耗散的增加使月球摆脱了准共振。对于包含> 2 l_em的影响后系统,准共和度逃逸后的最终角动量值仍明显高于当前的地球蒙蒙值。
Forming the Moon by a high-angular momentum impact may explain the Earth-Moon isotopic similarities, however, the post-impact angular momentum needs to be reduced by a factor of 2 or more to the current value (1 L_EM) after the Moon forms. Capture into the evection resonance, occurring when the lunar perigee precession period equals one year, could remove the angular momentum excess. However the appropriate angular momentum removal appears sensitive to the tidal model and chosen tidal parameters. In this work, we use a constant-time delay tidal model to explore the Moon's orbital evolution through evection. We find that exit from formal evection occurs early and that subsequently, the Moon enters a quasi-resonance regime, in which evection still regulates the lunar eccentricity even though the resonance angle is no longer librating. Although not in resonance proper, during quasi-resonance angular momentum is continuously removed from the Earth-Moon system and transferred to Earth's heliocentric orbit. The final angular momentum, set by the timing of quasi-resonance escape, is a function of the ratio of tidal strength in the Moon and Earth and the absolute rate of tidal dissipation in the Earth. We consider a physically-motivated model for tidal dissipation in the Earth as the mantle cools from a molten to a partially molten state. We find that as the mantle solidifies, increased terrestrial dissipation drives the Moon out of quasi-resonance. For post-impact systems that contain >2 L_EM, final angular momentum values after quasi-resonance escape remain significantly higher than the current Earth-Moon value.