The orbital architecture of the solar system is thought to have been sculpted by a dynamical instability among the giant planets. During the instability a primordial outer disk of planetesimals was destabilized and ended up on planet-crossing orbits. Most planetesimals were ejected into interstellar space, but a fraction were trapped on stable orbits in the Kuiper Belt and Oort cloud. We use a suite of N-body simulations to map out the diversity of planetesimals’ dynamical pathways. We focus on two processes: tidal disruption from very close encounters with a giant planet, and loss of surface volatiles from repeated passages close to the Sun. We show that the rate of tidal disruption is more than a factor of 2 higher for ejected planetesimals than for surviving objects in the Kuiper Belt or Oort cloud. Ejected planetesimals are preferentially disrupted by Jupiter and surviving ones by Neptune. Given that the gas giants contracted significantly as they cooled but the ice giants did not, taking into account the thermal evolution of the giant planets decreases the disruption rate of ejected planetesimals. The frequency of volatile loss and extinction is far higher for ejected planetesimals than for surviving ones and is not affected by the giant planets’ contraction. Even if all interstellar objects were ejected from solar system–like systems, our analysis suggests that their physical properties should be more diverse than those of solar system small bodies as a result of their divergent dynamical histories. This is consistent with the characteristics of the two currently known interstellar objects.

人们认为，太阳系的轨道结构是由巨型行星之间的动态不稳定性雕刻而成的。在不稳定过程中，原始的小行星外盘不稳定，并最终进入了穿越行星的轨道。大多数行星都被射入星际空间，但是一部分被困在柯伊伯带和奥尔特云的稳定轨道上。我们使用一组N体仿真，以绘制出小行星动力学路径的多样性。我们专注于两个过程：与巨型行星的非常近距离相遇引起的潮汐破坏，以及靠近太阳的反复通道造成的表面挥发物损失。我们显示，对于弹出的小行星，潮汐破坏的速度比在柯伊伯带或奥尔特云中幸存的物体高2倍以上。射出的小行星优先被木星破坏，幸存的小行星被海王星破坏。考虑到气体巨人在冷却时会明显收缩，而冰巨人却没有，考虑到巨型行星的热演化，会降低喷射出的小行星的破坏率。喷出的小行星的挥发损失和灭绝的频率远高于幸存的小行星，并且不受巨行星收缩的影响。即使所有星际物体都从类似太阳系的系统中弹出，我们的分析也表明，由于它们的动态历史不同，它们的物理性质应比太阳系小型物体的物理性质更多样化。这与两个当前已知的星际天体的特征一致。