论文标题
用rosetta/rosina dfms测量的水和烷烃的高d/h比在67p/churyumov-gerasimenko中的高d/h比
High D/H ratios in water and alkanes in comet 67P/Churyumov-Gerasimenko measured with the Rosetta/ROSINA DFMS
论文作者
论文摘要
彗星中的同位素丰度是理解太阳系材料的历史和起源的关键。水中的氘与氢（D/h）比率可用于多个彗星。然而，尚未据报道彗星在太阳绕太阳中的水的D/H比的长期研究。线性烷烃是重要的有机分子，在包括彗星在内的几个太阳系体上发现。迄今为止，只有线性烷烃中D/H和13C/12C的同位素比的上限。 这项工作的目的是对整个Rosetta任务中水比的详细分析。此外，还提供了67p/churyumov-gerasimenko的昏迷中前四个线性烷烃中D/H和13C/12C比率的首次测定。我们分析了Rosetta/Rosina双聚焦质谱仪（DFM）的原位测量。 HDO/H2O的D/H比和H216O/H217O的16o/17o比在2014年至2016年之间在太阳周围的太阳段落中没有变化。所有D/H的比率测量都兼容，在1 $σ$之内，平均值为$ 5.01 \ times10^times10^^{ - 44} $ 2.0％，其平均值为$ 5.01^＆2.0％。这表明67p的昏迷中的D/H比独立于地中心距离，彗星活动水平以及相对于核的航天器位置。另外，可以比以前更高的精度确定16o/17o的比率，相对变化为2.3％，值为2347。对于烷烃，D/H的比率比H2O高的4.1至4.8倍，而13C/12C比率在不确定性内兼容，并且具有其他太阳系对象的数据。烷烃中相对较高的D/H比与其他彗星有机分子一致，并表明这些有机物可以从太阳系形成的前极分子云中遗传。
Isotopic abundances in comets are key to understanding the history and origin of material in the Solar System. Deuterium-to-hydrogen (D/H) ratios in water are available for several comets. However, no long-term studies of the D/H ratio in water of a comet during its passage around the Sun have been reported. Linear alkanes are important organic molecules, which have been found on several Solar System bodies, including comets. To date, only upper limits of isotopic ratios for D/H and 13C/12C in linear alkanes are available. The aim of this work is a detailed analysis of the D/H ratio in water during the whole Rosetta mission. In addition, a first determination of the D/H and 13C/12C ratios in the first four linear alkanes in the coma of 67P/Churyumov-Gerasimenko is provided. We analysed in situ measurements from the Rosetta/ROSINA Double Focusing Mass Spectrometer (DFMS). The D/H ratio from HDO/H2O and the 16O/17O ratio from H216O/H217O did not change during 67P's passage around the Sun between 2014 and 2016. All D/H ratio measurements were compatible, within 1$σ$, with the mean value of $5.01\times10^{-4}$ and its relative variation of 2.0%. This suggests that the D/H ratio in 67P's coma is independent of heliocentric distance, level of cometary activity, as well as spacecraft location with respect to the nucleus. Additionally, the 16O/17O ratio could be determined with a higher accuracy than previously possible, yielding a value of 2347 with a relative variation of 2.3%. For the alkanes, the D/H ratio is between 4.1 and 4.8 times higher than in H2O, while the 13C/12C ratio is compatible, within uncertainties, with data for other Solar System objects. The relatively high D/H ratio in alkanes is in line with other cometary organic molecules and suggests that these organics may be inherited from the presolar molecular cloud from which the Solar System formed.
