嫦娥三号月基紫外望远镜观测到的月球外大气层含水量的一个前所未有的约束
An Unprecedented Constraint on Water Content in the Sunlit Lunar Exosphere Seen by Lunar-Based Ultraviolet Telescope of Chang'e-3 Mission
摘要：
月球稀薄外逸层中$\mathrm{OH/H_2O}$分子的含量目前仍是一个悬而未决的问题。我们在这里报告了一个前所未有的上限的OH自由基的含量，这是从现场测量进行的\rm的月基紫外望远镜，中国嫦娥三号任务的有效载荷。通过分析望远镜拍摄的图像中的漫射背景，推断OH自由基的柱密度和表面浓度分别为$<10^{11}\ \mathrm{cm^{-2}}$和$<10^{4}\ \mathrm{cm^{-3}}$（通过假设100 km标度高度的流体静力学平衡），假设记录的背景完全由它们的共振荧光发射贡献。所得浓度比先前报道的值低约两个数量级，并且接近溅射模型的预测。此外，相同的测量和方法允许我们推导出中性镁的$<10^{2}\ \mathrm{cm^{-3}}$的表面浓度，其比先前报道的上限低约两个数量级。这些结果是迄今为止月球外逸层中OH（MgI）含量的最佳结果。
英文摘要：
The content of $\mathrm{OH/H_2O}$ molecules in the tenuous exosphere of the Moon is still an open issue at present. We here report an unprecedented upper limit of the content of the OH radicals, which is obtained from the in-situ measurements carried out \rm by the Lunar-based Ultraviolet Telescope, a payload of Chinese Chang'e-3 mission. By analyzing the diffuse background in the images taken by the telescope, the column density and surface concentration of the OH radicals are inferred to be $<10^{11}\ \mathrm{cm^{-2}}$ and $<10^{4}\ \mathrm{cm^{-3}}$ (by assuming a hydrostatic equilibrium with a scale height of 100km), respectively, by assuming that the recorded background is fully contributed by their resonance fluorescence emission. The resulted concentration is lower than the previously reported value by about two orders of magnitude, and is close to the prediction of the sputtering model. In addition, the same measurements and method allow us to derive a surface concentration of $<10^{2}\ \mathrm{cm^{-3}}$ for the neutral magnesium, which is lower than the previously reported upper limit by about two orders of magnitude. These results are the best known of the OH (MgI) content in the lunar exosphere to date.
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。
