论文标题
通过建模观察数据来确定彗星表面发射分布的局限性 - 基于Rosetta观察的案例研究
Limitations in the determination of surface emission distributions on comets through modelling of observational data -- A case study based on Rosetta observations
论文作者
论文摘要
欧洲航天局（ESA）的罗塞塔（Rosetta）任务已将大量数据集返回了67p/churyumov-gerasimenko彗星内部气体昏迷的大量测量值。这些测量已被不同的组使用来确定核表面气源的分布。发现的解决方案彼此之间有很大不同，并说明了这个问题的堕落。这项工作的目的是探讨当前气体模型将昏迷测量与表面联系起来的局限性。特别是，我们讨论了Rosetta的Rosina/Cop，Virtis和Miro Instruments的敏感性，以区分气体发射与表面的截然不同的空间分布。我们已经应用了最先进的3D DSMC气体动力学代码的状态，以模拟不同模型的内部气体昏迷，这些模型在包含冰和不同尺寸的活性斑块的表面上有所不同。这些不同的分布导致喷气相互作用在动态行为上有所不同。我们发现Rosina/Cops测量本身无法检测到我们的模型中的差异。尽管Rosina/COPS的测量对于限制气体排放的区域不均匀性很重要，但它们本身不能确定气体的表面发射分布比几百米（400 m）更好的空间精度。因此，任何适合Rosina/COPS测量值的解决方案都是从根本上退化的，无论是通过正向还是反向模型。在我们在这里为Virtis和Miro展示的，只有其他具有互补测量的仪器可以提高这种堕落性。最后，作为副产品，我们探索了活动分布对表面侧流的影响，这可能是某些观察到的风体特征。
The European Space Agency's (ESA) Rosetta mission has returned a vast data set of measurements of the inner gas coma of comet 67P/Churyumov-Gerasimenko. These measurements have been used by different groups to determine the distribution of the gas sources at the nucleus surface. The solutions that have been found differ from each other substantially and illustrate the degeneracy of this issue. It is the aim of this work to explore the limitations that current gas models have in linking the coma measurements to the surface. In particular, we discuss the sensitivity of Rosetta's ROSINA/COPS, VIRTIS, and MIRO instruments to differentiate between vastly different spatial distributions of the gas emission from the surface. We have applied a state of the art 3D DSMC gas dynamics code to simulate the inner gas coma of different models that vary in the fraction of the surface that contains ice and in different sizes of active patches. These different distributions result in jet interactions that differ in their dynamical behaviour. We have found that ROSINA/COPS measurements by themselves cannot detect the differences in our models. While ROSINA/COPS measurements are important to constrain the regional inhomogeneities of the gas emission, they can by themselves not determine the surface emission distribution of the gas sources to a spatial accuracy of better than a few hundred metres (400 m). Any solutions fitting the ROSINA/COPS measurements is hence fundamentally degenerate, be it through a forward or inverse model. Only other instruments with complementary measurements can potentially lift this degeneracy as we show here for VIRTIS and MIRO. Finally, as a by-product, we have explored the effect of our activity distributions on lateral flow at the surface that may be responsible for some of the observed aeolian features.
