Massive gaseous nebula has been a key element to formation of large solid objects (planetesimals, giant planet cores) in the early phase of the Solar system evolution. Here, we focus on its effects during the stage when giant planets have already fully formed. Dynamical effects of the nebula on motion of planetesimals stirred by planets were twofold: (i) global gravitational acceleration, and (ii) local aerodynamic drag. Thanks to decreasing gas density with radial distance, in the outer Solar system the effect of the drag was deemed to be important only for small planetesimals (sizes \(\lesssim 10\) km). However, we find that it was possibly important up to the sizes of \(\simeq 100\) km as well. The gravitational field of the nebula produces secular oscillations of the orbital eccentricity and inclination of planetesimals. Eventually, their pericenter may be lifted away from strong planetary influence, exhibited during close encounters, even for small bodies born in the planetary heliocentric zone. It has been previously suggested that such pathway may, in some nebula models, launch planetesimals onto large-inclination and small-eccentricity orbits in the trans-Neptunian region. These orbits would be dynamically stable to present epoch. Our simulations generally do not support such extreme cases, but we find that, after the nebula disperses, some planetesimals may indeed reach low-inclination and low-eccentricity orbits exterior to Neptune. These bodies may have been implanted into the Kuiper belt during subsequent planetesimal-driven migration of planets. This raises a possibility that some present-day KBOs may have formed in the giant-planet zone (5–20 au).

中文翻译：

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原行星状星云对太阳系外星子轨道动力学的影响

在太阳系演化的早期阶段，巨大的气态星云一直是大型固体物体（微行星、巨行星核心）形成的关键因素。在这里，我们关注它在巨行星已经完全形成阶段的影响。星云对行星搅动的微星运动的动力学影响是双重的：（i）全球重力加速度，和（ii）局部气动阻力。由于气体密度随径向距离降低，在外太阳系中，阻力的影响被认为仅对小行星（尺寸 \(\lesssim 10\) km）很重要。然而，我们发现在 \(\simeq 100\) km 的大小之前它可能也很重要。星云的引力场产生轨道偏心率和星子倾角的长期振荡。最终，它们的近心可能会远离强烈的行星影响，在近距离接触时会表现出来，即使是对于出生在行星日心带的小天体。之前有人提出，在某些星云模型中，这种路径可能会将星子发射到跨海王星区域的大倾角和小偏心率轨道上。这些轨道在当前时期将是动态稳定的。我们的模拟通常不支持这种极端情况，但我们发现，在星云分散之后，一些星子确实可能到达海王星外部的低倾角和低离心率轨道。这些天体可能是在随后由星子驱动的行星迁移过程中被植入柯伊伯带的。这增加了在巨行星带（5-20​​ au）中可能已经形成一些现代 KBO 的可能性。