论文标题

(486958)ARROKOTH的升华演变

The Sublimative Evolution of (486958) Arrokoth

论文作者

Steckloff, Jordan K., Lisse, Carey M., Safrit, Taylor K., Bosh, Amanda S., Lyra, Wladimir, Sarid, Gal

论文摘要

我们考虑了新视野目标的历史(486958)在其崇高演化的背景下。太阳的原行星磁盘(PPD)清除后不久,新强烈的阳光引发了Arrokoth的早期历史上的升华时期,持续了〜10-100 Myr。尽管这种升华太弱了,无法显着改变Arrokoth的自旋状态,但它可能会驱动足够有效的表面周围的质量传输,以擦除〜10-100 m的长度尺度上的地形特征。这包括直径高达约50-500 m的陨石坑,这表明大多数Arrokoth的陨石坑可能不是原始的(从Arrokoth的Lobes的合并中),而是可以追溯到这个过热时期结束后。此后,Arrokoth进入了一个静止期(持续到今天),其中挥发性生产率至少比〜10^24分子/s检测限制的新视野航天器的〜10^24分子(Lisse etal。2020)小。这不足以驱动质量运输或升华扭矩。这些结果表明,观察到的arrokoth表面不是原始的,而是静止时期的日期。相比之下,升华的扭矩无法有意义地改变Arrokoth的旋转状态表明其形状确实是原始的,并且其观察到的旋转代表了形成后其旋转状态。

We consider the history of New Horizons target (486958) Arrokoth in the context of its sublimative evolution. Shortly after the Sun's protoplanetary disk (PPD) cleared, the newly intense sunlight sparked a sublimative period in Arrokoth's early history that lasted for ~10-100 Myr. Although this sublimation was too weak to significantly alter Arrokoth's spin state, it could drive mass transport around the surface significant enough to erase topographic features on length scales of ~10-100 m. This includes craters up to ~50-500 m in diameter, which suggests that the majority of Arrokoth's craters may not be primordial (dating from the merger of Arrokoth's lobes), but rather could date from after the end of this sublimative period. Thereafter, Arrokoth entered a Quiescent Period (which lasts to the present day), in which volatile production rates are at least 13 orders of magnitude less than the ~10^24 molecules/s detection limit of the New Horizons spacecraft (Lisse et al. 2020). This is insufficient to drive either mass transport or sublimative torques. These results suggest that the observed surface of Arrokoth is not primordial, but rather dates from the Quiescent Period. By contrast, the inability of sublimative torques to meaningfully alter Arrokoth's rotation state suggests that its shape is indeed primordial, and its observed rotation is representative of its spin state after formation.

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