Mass Distribution and Planet Formation in the Solar Nebula
Mass Distribution and Planet Formation in the Solar Nebula
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太阳星云中的质量分布和行星形成
DOI：
10.1086/522825
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发表时间：
2007
期刊：
影响因子：
--
通讯作者：
S. Desch
中科院分区：
文献类型：
--
作者：
S. Desch
太阳星云原行星盘的表面密度分布是所有盘过程和演化模型的基本输入。传统上，它是通过将行星的增大质量分布在行星今天所环绕的环带上来估计的，即所谓的最小质量太阳星云。这样做隐含的假设是行星完全吸积了所有在其喂养区的星子，但这一假设尚未得到验证。事实上，天王星和海王星的生长模型预测，这些行星不可能在盘的寿命内生长到~10 M，即使它们必须这样，以吸积H/He大气。在本文中，我们采用了行星动力学的“尼斯”模型（Tsiganis和同事），其中太阳系开始在一个更紧凑的配置行星的起始位置。我们得到了一个表面密度分布，它很好地近似于幂律ψ（r）= 343（fp/0.5）-1（r/10 Au）-2.168 g cm-2，其中fp是固体质量中以星子形式存在的部分。我们表明，这种配置文件是不一致的稳态吸积盘，但与稳态递减盘，被光蒸发是一致的。我们计算的背景下，这个磁盘模型的行星的增长，并证明了第一次，所有的巨行星可以实现其孤立的质量和开始吸积H/He大气的磁盘的寿命内。我们推断的天王星（r）与行星的增广质量的拟合非常好（<10%），但前提是天王星和海王星在太阳系演化的早期交换了位置，这是尼斯模型预测的可能性。
The surface density profile Σ(r) of the solar nebula protoplanetary disk is a fundamental input to all models of disk processes and evolution. Traditionally it is estimated by spreading out the augmented masses of the planets over the annuli in which the planets orbit today, the so-called minimum-mass solar nebula. Doing so implicitly assumes that the planets completely accreted all planetesimals in their feeding zones, but this assumption has not been tested. Indeed, models of the growth of Uranus and Neptune predict that these planets could not have grown to ~10 M⊕ within the lifetime of the disk, even though they must have, to accrete H/He atmospheres. In this paper we adopt the starting positions of the planets in the "Nice" model of planetary dynamics (Tsiganis and coworkers), in which the solar system started in a much more compact configuration. We derive a surface density profile that is well approximated by the power law Σ(r) = 343(fp/0.5)-1(r/10 AU)-2.168 g cm-2, where fp is the fraction of the solid mass in the form of planetesimals. We show that this profile is inconsistent with a steady state accretion disk but is consistent with a steady state decretion disk that is being photoevaporated. We calculate the growth of planets in the context of this disk model and demonstrate for the first time that all of the giant planets can achieve their isolation masses and begin to accrete H/He atmospheres within the lifetime of the disk. The fit of our inferred Σ(r) to the augmented masses of the planets is excellent (<10%), but only if Uranus and Neptune swtiched places early in the solar system's evolution, a possibility predicted by the Nice model.