巨行星上的尘埃消融：平流层光化学的结果
Dust Ablation on the Giant Planets: Consequences for Stratospheric Photochemistry
摘要：
行星际尘埃的消融为木星、土星、天王星和海王星的上层大气提供了氧气。利用最近的动力学模型预测尘埃流入巨行星的速率（Poppe，A.R.~等~ [2016]，Icarus 264，369），我们计算了烧蚀剖面，并研究了这些行星平流层中随后的耦合氧-烃中性光化学。我们发现，来自埃奇奥-柯伊伯带、彗星族彗星和奥尔特云彗星的尘埃颗粒提供的有效氧流入率为：1.0 $^{+2.2}_{-0.7} \, \times \, 10^7$ O原子cm $^{-2}$ s $^{-1}$到木星，7.4 $^{+16}_{-5.1} \, \times 10^4$ cm $^{-2}$ s $^{-1}$到土星，8.9 $^{+19}_{-6.1} \, \times \, 10^4$ cm $^{-2}$ s $^{-1}$到天王星，7.5 $^{+16}_{-5.1} \, \times \, 10^5$ cm $^{-2}$ s $^{-1}$到海王星。烧蚀的氧的命运部分取决于最初输送的产物的分子/原子形式，以及它沉积的高度。平流层的主要产物是CO、H $_2$ O和CO $_2$，它们在光化学上相对稳定。模型数据的比较表明，行星际尘埃颗粒提供了一个重要组成部分的外部氧气木星和天王星，但远远低于所需的量来解释目前在土星和海王星的平流层中看到的CO丰度。我们的结果与所有巨行星在过去几百年内都经历过大彗星撞击的理论一致。我们的研究结果还表明，低背景H $_2$ O丰度在木星的平流层是有效的流星氧转化为CO的过程中或之后立即烧蚀-光化学本身不能有效地转换成CO的H $_2$ O的巨行星。
英文摘要：
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 1.0$^{+2.2}_{-0.7} \, \times \, 10^7$ O atoms cm$^{-2}$ s$^{-1}$ to Jupiter, 7.4$^{+16}_{-5.1} \, \times 10^4$ cm$^{-2}$ s$^{-1}$ to Saturn, 8.9$^{+19}_{-6.1} \, \times \, 10^4$ cm$^{-2}$ s$^{-1}$ to Uranus, and 7.5$^{+16}_{-5.1} \, \times \, 10^5$ cm$^{-2}$ s$^{-1}$ 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, H$_2$O, and CO$_2$, 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 H$_2$O 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 H$_2$O into CO on the giant planets.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
