标题： 自由漂浮还是仅仅分离？ 显示英文标题

标题： Free Floating or Merely Detached?

摘要： 微引力透镜调查表明存在一个出人意料的大数量的自由漂浮行星，每颗恒星大约有两倍海王星质量的行星。 这类物体的起源尚不清楚，我们也不知道它们是否真正不受束缚，还是仅仅围绕其母恒星在较大的距离上运行。 在此，我们通过不稳定的多行星系统的数值模拟来研究行星间散射作为可能的起源。 我们发现，通过散射导致的行星逃逸可能很缓慢，对于在几AU及更远轨道上的海王星质量散射体，通常需要超过数十亿年。 此外，这一过程必然将行星送入数百AU的轨道，这些轨道免受进一步散射的影响。 我们将这些称为“分离”行星。 根据散射假说，我们估计约有一半的“自由漂浮”海王星并非真正自由，而是仅仅是“分离”的。 显示英文摘要

摘要： Microlensing surveys suggest the presence of a surprisingly large population of free-floating planets, with a rate of about two Neptunes per star. The origin of such objects is not known, neither do we know if they are truly unbound or are merely orbiting at large separations from their host stars. Here, we investigate planet-planet scattering as a possible origin through numerical simulations of unstable multi-planet systems. We find that planet ejection by scattering can be slow, often taking more than billions of years for Neptune-mass scatterers orbiting at a few AU and beyond. Moreover, this process invariably delivers planets to orbits of hundreds of AU that are protected from further scattering. We call these ``detached" planets. Under the scattering hypothesis, we estimate that about half of the reported ``free-floating" Neptunes are not free but merely ``detached".