An age–colour relationship for main-belt S-complex asteroids
An age–colour relationship for main-belt S-complex asteroids
复制标题
主带 S 复合体小行星的年龄与颜色关系
作者：
R. Jedicke;D. Nesvorný;R. Whiteley;Ž. Ivezić;M. Jurić
主带中的小行星碰撞产生的碎片最终可能会以陨石的形式落在地球上。因此，数量最多的陨石(普通球粒陨石，OC)的实验室光谱与其推定的(S杂岩)小行星母体的遥感观测表面光谱不匹配，这一直是行星科学界的一个难题。对这一令人困惑的观测提出的解决方案之一是，随着时间的推移，空间风化通过各种过程(如太阳和宇宙射线的轰击，微陨石的轰击，等等)来改变暴露的行星表面。已经在月球样本上观察到了空间风化，在地球上的实验室实验中，从航天器数据中有很好的证据表明，这一过程在小行星表面是活跃的。本文利用小行星家族的年龄与颜色的关系，对S杂岩主带小行星的空间风化速率进行了测量。将这种年龄-颜色关系外推到非常年轻的年龄，可以得到与新切割的OC陨石样本很好的匹配，为它们与S杂岩小行星之间的遗传关系提供了强有力的支持。
Asteroid collisions in the main belt eject fragments that may eventually land on Earth as meteorites. It has therefore been a long-standing puzzle in planetary science that laboratory spectra of the most populous class of meteorite (ordinary chondrites, OC) do not match the remotely observed surface spectra of their presumed (S-complex) asteroidal parent bodies. One of the proposed solutions to this perplexing observation is that ‘space weathering’ modifies the exposed planetary surfaces over time through a variety of processes (such as solar and cosmic ray bombardment, micro-meteorite bombardment, and so on). Space weathering has been observed on lunar samples, in Earth-based laboratory experiments, and there is good evidence from spacecraft data that the process is active on asteroid surfaces. Here, we present a measurement of the rate of space weathering on S-complex main-belt asteroids using a relationship between the ages of asteroid families and their colours. Extrapolating this age–colour relationship to very young ages yields a good match to the colour of freshly cut OC meteorite samples, lending strong support to a genetic relationship between them and the S-complex asteroids.