标题： 1. 1I/'Oumuamua 是一颗地外冥王星表面的N2冰碎片。 II. N2冰碎片的产生与'Oumuamua的起源 显示英文标题

标题： 1I/'Oumuamua as an N2 ice fragment of an exo-pluto surface. II. Generation of N2 ice fragments and the origin of 'Oumuamua

摘要： 星际天体1I/'奥陌陌'的起源一直未能得到解释。 在一篇相关论文（Jackson & Desch, 2021）中，我们表明，在观测时轴向为45米 x 44米 x 7.5米的N2冰体与它的反照率、非引力加速度以及未观测到CO、CO2或尘埃一致。 在这里，我们证明了对冥王星类柯伊伯带天体（KBOs）表面的撞击会生成并喷射约10^14个碰撞碎片——其中大约一半是H2O冰碎片，另一半是N2冰碎片——这是由于耗尽原始柯伊伯带的动力学不稳定性引起的。 我们展示了这些数字与我们观测到类似1I/'奥陌陌'的星际天体以及更像彗星的2I/鲍里索夫天体的频率之间的一致性，前提是其他恒星系统以类似于太阳的效率喷射此类天体；由此推断，分化后的KBOs和导致撞击碎片喷射的动力学不稳定性可能是大多数系外系统的普遍现象。 银河宇宙射线会在45亿年内侵蚀这些碎片，因此碎片仅占长周期奥尔特彗星的极小部分（~0.1%），但C/2016 R2可能是一个例子。 我们估计'奥陌陌'大约在0.4-0.5亿年前被弹出，来自一个年轻的（~10^8年）恒星系统，我们推测它位于英仙臂。 像'奥陌陌'这样的天体可以直接探测到一种前所未见类型的系外行星的表面成分： “系外冥王星”。 '奥陌陌'可能是我们从系外行星获取的第一个样本。 显示英文摘要

摘要： The origin of the interstellar object 1I/'Oumuamua, has defied explanation. In a companion paper (Jackson & Desch, 2021), we show that a body of N2 ice with axes 45 m x 44 m x 7.5 m at the time of observation would be consistent with its albedo, non-gravitational acceleration, and lack of observed CO or CO2 or dust. Here we demonstrate that impacts on the surfaces of Pluto-like Kuiper belt objects (KBOs) would have generated and ejected ~10^14 collisional fragments--roughly half of them H2O ice fragments and half of them N2 ice fragments--due to the dynamical instability that depleted the primordial Kuiper belt. We show consistency between these numbers and the frequency with which we would observe interstellar objects like 1I/'Oumuamua, and more comet-like objects like 2I/Borisov, if other stellar systems eject such objects with efficiency like that of the Sun; we infer that differentiated KBOs and dynamical instabilities that eject impact-generated fragments may be near-universal among extrasolar systems. Galactic cosmic rays would erode such fragments over 4.5 Gyr, so that fragments are a small fraction (~0.1%) of long-period Oort comets, but C/2016 R2 may be an example. We estimate 'Oumuamua was ejected about 0.4-0.5 Gyr ago, from a young (~10^8 yr) stellar system, which we speculate was in the Perseus arm. Objects like 'Oumuamua may directly probe the surface compositions of a hitherto-unobserved type of exoplanet: "exo-plutos". 'Oumuamua may be the first sample of an exoplanet brought to us.