标题： 火星卫星由小行星的破坏性部分捕获形成 显示英文标题

标题： Origin of Mars's moons by disruptive partial capture of an asteroid

摘要： 火星的两颗小卫星，火卫一和火卫二的起源仍然未知。 它们通常被认为是被捕获的小行星，或者是由一次巨大撞击产生的碎片盘中累积形成的。 在此，我们提出一种替代情景，即潮汐破坏的小行星碎片被俘获并演化成碰撞性原始卫星盘。 我们模拟了初始破坏以及碎片随后的轨道演化。 我们发现，在太阳-火星框架中，不同近火点距离、速度、质量、自转和取向下，未束缚小行星质量的百分之几十可以被俘获并在碰撞时间尺度之外存活下来。 此外，超过小行星质量百分之一的部分可能在卫星的累积区域内实现圆形化。 这意味着母体的质量要求比巨大撞击更低，这可能增加通过这种途径形成原始卫星盘的可能性，与直接捕获不同，这种途径还能自然解释卫星的轨道。 这三个形成情景各自暗示了火星卫星的不同特性，将由即将开展的航天器任务进行检验。 显示英文摘要

摘要： The origin of Mars's small moons, Phobos and Deimos, remains unknown. They are typically thought either to be captured asteroids or to have accreted from a debris disk produced by a giant impact. Here, we present an alternative scenario wherein fragments of a tidally disrupted asteroid are captured and evolve into a collisional proto-satellite disk. We simulate the initial disruption and the fragments' subsequent orbital evolution. We find that tens of percent of an unbound asteroid's mass can be captured and survive beyond collisional timescales, across a broad range of periapsis distances, speeds, masses, spins, and orientations in the Sun--Mars frame. Furthermore, more than one percent of the asteroid's mass could evolve to circularise in the moons' accretion region. This implies a lower mass requirement for the parent body than that for a giant impact, which could increase the likelihood of this route to forming a proto-satellite disk that, unlike direct capture, could also naturally explain the moons' orbits. These three formation scenarios each imply different properties of Mars's moons to be tested by upcoming spacecraft missions.