The detection of a water-rich plume erupting from ‘tiger stripes’ near the Enceladus south polar region is an important discovery of geologically active satellites within the Solar system. In this work, we apply an analytical approach to model the plume structure, using as a diagnostic the CO2 distribution extracted from the Cassini Ion and Neutral Mass Spectrometer measurements made during the E14, E17, and E18 flybys. Special focus is placed on the modelling of the spike-like structures by including only sources with substantial contributions to the plume densities. Such a procedure reduces greatly the model complexity and helps to better constrain the source parameters. Both the model source rate and Mach number are found to vary considerably among different sources during the same flyby and also among different flybys for the same source, revealing a complicated spatio-temporal variability in the plume structure. Our analysis suggests a total escape rate of (1.0–7.1) × 1026 s−1 for CO2 and (2.4–6.6) × 1028 s−1 for H2O, in broad agreement with previous estimates. Of particular interest is our identification of a tentative correlation between the Mach number and thermal brightness, of which the latter is a tracer of the geological activity of the emission source. Such a relation should be able to provide more insights into the nature of geyser emission along the ‘tiger stripes’.

中文翻译：

---

关于土卫二羽流的结构

探测到从土卫二南极地区附近的“虎纹”喷发的富水羽流是太阳系内地质活跃卫星的重要发现。在这项工作中，我们应用分析方法来模拟羽流结构，使用从 E14、E17 和 E18 飞越期间进行的卡西尼离子和中性质谱仪测量中提取的 CO2 分布作为诊断。通过仅包括对羽流密度有重大贡献的源，特别关注尖峰状结构的建模。这样的过程大大降低了模型的复杂性，并有助于更好地约束源参数。发现模型源速率和马赫数在同一飞越期间的不同源之间以及同一源的不同飞越之间差异很大，揭示了羽流结构中复杂的时空变化。我们的分析表明，CO2 的总逃逸率为 (1.0-7.1) × 1026 s-1，H2O 的总逃逸率为 (2.4-6.6) × 1028 s-1，与之前的估计基本一致。我们特别感兴趣的是我们确定了马赫数和热亮度之间的暂定相关性，后者是排放源地质活动的示踪剂。这种关系应该能够提供更多关于沿“虎纹”的间歇泉排放性质的见解。我们特别感兴趣的是我们确定了马赫数和热亮度之间的暂定相关性，后者是排放源地质活动的示踪剂。这种关系应该能够提供更多关于沿“虎纹”的间歇泉排放性质的见解。我们特别感兴趣的是我们确定了马赫数和热亮度之间的暂定相关性，后者是排放源地质活动的示踪剂。这种关系应该能够提供更多关于沿“虎纹”的间歇泉排放性质的见解。