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arXiv 2104.11252astro-ph.EP
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水星起源的动力学途径II:在地球内部盘的原位形成

Dynamical avenues for Mercury's origin II: in-situ formation in the inner terrestrial disk

Matthew S. Clement, John E. Chambers

摘要:

现代的类地行星形成模型非常成功地产生了质量和轨道与地球和金星相似的行星。与岩石系外行星的多行星系统的经典理论预测和推断的人口统计数据形成鲜明对比,金星和地球与邻近的水星和火星之间的质量(>10)和轨道周期(>2)比在数值生成的系统中并不常见。虽然小火星问题的可行解决方案在文献中非常丰富,但水星的特殊起源仍然相当神秘。在本文中,我们调查的可能性,水星形成在一个质量耗尽,内部区域的地球盘(a < 0.5 au)。这种机制在类地行星形成模型中经常被忽略,因为在1亿年时间尺度上分辨数百个短周期天体的计算成本很高。通过测试多个磁盘配置文件和质量分布,我们确定了几个有前途的初始条件,导致非常成功的模拟系统。特别是,我们最成功的模拟考虑中等总质量的汞形成物质(0.1-0.25地球质量)。虽然较大的初始质量往往会产生不成比例的水星类似物,但较小的值往往会抑制行星的形成,因为整个区域的物质很容易被金星吸积。此外,我们发现,浅的表面密度分布和较大的库存的小微行星适度提高充分复制水星的可能性。

英文摘要:

Modern terrestrial planet formation models are highly successful at consistently generating planets with masses and orbits analogous to those of Earth and Venus. In stark contrast to classic theoretical predictions and inferred demographics of multi-planet systems of rocky exoplanets, the mass (>10) and orbital period (>2) ratios between Venus and Earth and the neighboring Mercury and Mars are not common outcomes in numerically generated systems. While viable solutions to the small-Mars problem are abundant in the literature, Mercury's peculiar origin remains rather mysterious. In this paper, we investigate the possibility that Mercury formed in a mass-depleted, inner region of the terrestrial disk (a < 0.5 au). This regime is often neglected in terrestrial planet formation models because of the high computational cost of resolving hundreds of short-period objects over ~100 Myr timescales. By testing multiple disk profiles and mass distributions, we identify several promising sets of initial conditions that lead to remarkably successful analog systems. In particular, our most successful simulations consider moderate total masses of Mercury-forming material (0.1-0.25 Earth masses). While larger initial masses tend to yield disproportionate Mercury analogs, smaller values often inhibit the planets' formation as the entire region of material is easily accreted by Venus. Additionally, we find that shallow surface density profiles and larger inventories of small planetesimals moderately improve the likelihood of adequately reproducing Mercury.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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