标题： 1I/'Oumuamua作为地外冥王星表面的N2冰碎片：I. 大小和成分限制 显示英文标题

标题： 1I/'Oumuamua as an N2 ice fragment of an exo-Pluto surface: I. size and compositional constraints

摘要： 星际物体1I/‘奥陌陌’的起源一直无法解释。 我们计算了由各种不同的冰组成的天体可能经历的非引力加速度，并证明由N₂冰组成的天体会满足非引力加速度、大小和反照率以及未检测到CO或CO₂或尘埃发射的现有约束条件。 我们发现‘奥陌陌’当时距离太阳1.42天文单位时，尺寸为45米×44米×7.5米，具有0.64的高反照率。 这一反照率与冥王星和海卫一等天体的N₂表面一致。 我们估计‘奥陌陌’大约在0.4至0.5亿年前被弹射出一个年轻的恒星系统，可能位于英仙座臂。 像‘奥陌陌’这样的天体可以直接探测一种迄今未观测到的系外行星类型——“类冥王星”的表面组成。 在另一篇配套论文（Desch & Jackson, 2021）中，我们演示了其他恒星系统中类似柯伊伯带的动态不稳定性，可能能够产生并弹射大量N₂冰碎片。 ‘奥陌陌’可能是我们从系外行星获得的第一个样本。 显示英文摘要

摘要： The origin of the interstellar object 1I/'Oumuamua has defied explanation. We perform calculations of the non-gravitational acceleration that would be experienced by bodies composed of a range of different ices and demonstrate that a body composed of N2 ice would satisfy the available constraints on the non-gravitational acceleration, size and albedo, and lack of detectable emission of CO or CO2 or dust. We find that 'Oumuamua was small, with dimensions 45 m x 44 m x 7.5 m at the time of observation at 1.42 au from the Sun, with a high albedo of 0.64. This albedo is consistent with the N2 surfaces of bodies like Pluto and Triton. We estimate 'Oumuamua was ejected about 0.4-0.5 Gyr ago from a young stellar system, possibly in the Perseus arm. Objects like 'Oumuamua may directly probe the surface compositions of a hitherto-unobserved type of exoplanet: "exo-plutos". In a companion paper (Desch & Jackson, 2021) we demonstrate that dynamical instabilities like the one experienced by the Kuiper belt, in other stellar systems, plausibly could generate and eject large numbers of N2 ice fragments. 'Oumuamua may be the first sample of an exoplanet brought to us.