Onset of oligarchic growth and implication for accretion histories of dwarf planets
Onset of oligarchic growth and implication for accretion histories of dwarf planets
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寡头增长的开始及其对矮行星吸积历史的影响
DOI：
10.1016/j.icarus.2016.07.019
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发表时间：
2016
期刊：
影响因子：
3.2
通讯作者：
R. Morishima
中科院分区：
文献类型：
--
作者：
R. Morishima
我们用解析理论和数值模拟研究了从等质量星子开始的行星吸积。我们特别关注在寡头生长开始时的行星质量M oli如何依赖于星子的初始质量M 0。当相对于原行星的希尔速度的速度色散达到最小时，寡头生长就开始了。我们发现，如果m0足够小，在失控和寡头生长阶段之间的中间阶段，这种归一化速度色散变得低至1。在这种情况下，M oli与M 0无关。另一方面，如果m0较大，则寡头增长在失控增长之后直接开始，m oli∝m0 3/7。最小质量太阳星云的固体表面密度的行星质量M oli在M 0的合理范围内接近矮行星的质量。这表明它们很可能是未能成为行星的最大残余的星子。残余星子的微分质量分布的幂律指数q通常是- 2.0和- 2.7到- 2.5。当m = 0时，再现了热柯伊伯带天体质量分布的斜率q≃−2.7，以及在10 - 21 g（或半径50 km）处的碰撞。另一方面，质量小于等于0 ~ 10 13 g的小的初始星子有利于解释大小行星的斜率q≃−2.0，而10 21 g的起伏可以通过引入少量质量为10 19 g的小行星种子来重现。
We investigate planetary accretion that starts from equal-mass planetesimals using an analytic theory and numerical simulations. We particularly focus on how the planetary mass M oli at the onset of oligarchic growth depends on the initial mass m 0 of a planetesimal. Oligarchic growth commences when the velocity dispersion relative to the Hill velocity of the protoplanet takes its minimum. We find that if m 0 is small enough, this normalized velocity dispersion becomes as low as unity during the intermediate stage between the runaway and oligarchic growth stages. In this case, M oli is independent of m 0. If m 0 is large, on the other hand, oligarchic growth commences directly after runaway growth, and M oli∝ m 0 3/7. The planetary mass M oli for the solid surface density of the Minimum Mass Solar Nebula is close to the masses of the dwarf planets in a reasonable range of m 0. This indicates that they are likely to be the largest remnant planetesimals that failed to become planets. The power-law exponent q of the differential mass distribution of remnant planetesimals is typically− 2.0 and− 2.7 to− 2.5 for small and large m 0. The slope, q≃− 2.7, and the bump at 10 21 g (or 50 km in radius) for the mass distribution of hot Kuiper belt objects are reproduced if m 0 is the bump mass. On the other hand, small initial planetesimals with m 0∼ 10 13 g or less are favored to explain the slope of large asteroids, q≃− 2.0, while the bump at 10 21 g can be reproduced by introducing a small number of asteroid seeds each with mass of 10 19 g.
DOI：
10.1088/0004-637x/764/2/146
发表时间：
2012-08
期刊：
The Astrophysical Journal
影响因子：
--
作者：
P. Garaud;F. Meru;M. Galvagni;C. Olczak
通讯作者：
P. Garaud;F. Meru;M. Galvagni;C. Olczak
影响因子：
4.9
作者：
Leinhardt, Zoe M.;Stewart, Sarah T.
通讯作者：
Stewart, Sarah T.