Moses Julianne I, Poppe Andrew R
Space Science Institute, 4750 Walnut Street, Suite 205, Boulder, CO 80301, USA.
Space Sciences Laboratory, 7 Gauss Way, University of California, Berkeley, CA 94720, USA.
Icarus. 2017 Nov 15;297:33-58. doi: 10.1016/j.icarus.2017.06.002. Epub 2017 Jun 15.
Ablation of interplanetary dust supplies oxygen to the upper atmospheres of Jupiter, Saturn, Uranus, and Neptune. Using recent dynamical model predictions for the dust influx rates to the giant planets (Poppe, A.R. et al. [2016], Icarus 264, 369), we calculate the ablation profiles and investigate the subsequent coupled oxygen-hydrocarbon neutral photochemistry in the stratospheres of these planets. We find that dust grains from the Edgeworth-Kuiper Belt, Jupiter-family comets, and Oort-cloud comets supply an effective oxygen influx rate of O atoms cm s to Jupiter, cm s to Saturn, cm s to Uranus, and cm s to Neptune. The fate of the ablated oxygen depends in part on the molecular/atomic form of the initially delivered products, and on the altitude at which it was deposited. The dominant stratospheric products are CO, HO, and CO, which are relatively stable photochemically. Model-data comparisons suggest that interplanetary dust grains deliver an important component of the external oxygen to Jupiter and Uranus but fall far short of the amount needed to explain the CO abundance currently seen in the middle stratospheres of Saturn and Neptune. Our results are consistent with the theory that all of the giant planets have experienced large cometary impacts within the last few hundred years. Our results also suggest that the low background HO abundance in Jupiter's stratosphere is indicative of effective conversion of meteoric oxygen to CO during or immediately after the ablation process - photochemistry alone cannot efficiently convert the HO into CO on the giant planets.
行星际尘埃的消融给木星、土星、天王星和海王星的高层大气提供了氧气。利用最近对巨行星尘埃流入率的动力学模型预测（Poppe, A.R.等人[2016]，《伊卡洛斯》264, 369），我们计算了消融剖面，并研究了这些行星平流层中随后的氧 - 碳氢化合物耦合中性光化学过程。我们发现，来自柯伊伯带、木星族彗星和奥尔特云彗星的尘埃颗粒给木星提供的有效氧流入率为O原子·厘米⁻²·秒⁻¹，给土星提供的为 厘米⁻²·秒⁻¹，给天王星提供的为 厘米⁻²·秒⁻¹，给海王星提供的为 厘米⁻²·秒⁻¹。消融的氧的归宿部分取决于最初输送产物的分子/原子形式，以及其沉积的高度。平流层中的主要产物是CO、HO和CO，它们在光化学上相对稳定。模型与数据的比较表明，行星际尘埃颗粒给木星和天王星输送了外部氧的一个重要组成部分，但远远不足以解释目前在土星和海王星中层平流层中看到的CO丰度。我们的结果与所有巨行星在过去几百年内都经历了大型彗星撞击的理论一致。我们的结果还表明，木星平流层中低背景HO丰度表明在消融过程中或之后流星氧有效地转化为了CO——仅靠光化学不能在巨行星上有效地将HO转化为CO。
