Comprehensive Study of the Chemical Composition and Spatial Outgassing Behavior of Hyperactive Comet 46P/Wirtanen Using Near-IR Spectroscopy during its Historic 2018 Apparition
Comprehensive Study of the Chemical Composition and Spatial Outgassing Behavior of Hyperactive Comet 46P/Wirtanen Using Near-IR Spectroscopy during its Historic 2018 Apparition
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DOI：
10.3847/1538-3881/acc074
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发表时间：
2023-05
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通讯作者：
Y. Khan;E. Gibb;N. Roth;M. DiSanti;N. Dello Russo;B. Bonev;C. Ejeta;M. Saki;R. Vervack;A. McKay;H. Kawakita;M. Combi;D. Qasim;Y. Shou
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作者：
Y. Khan;E. Gibb;N. Roth;M. DiSanti;N. Dello Russo;B. Bonev;C. Ejeta;M. Saki;R. Vervack;A. McKay;H. Kawakita;M. Combi;D. Qasim;Y. Shou
我们提出了一个全面的分析的化学成分的彗星和潜在的航天器目标46 P/Wirtanen，在近红外波长范围。我们在NASA红外望远镜设施使用iSHELL在2018年12月和2019年1月和2月的11个前，近和后近日点日期观察彗星。我们报告的旋转温度，生产率，和混合比相对于H2O和C2 H6或3σ上限的主要挥发物H2O，HCN，CH 4，C2 H6，CH 3OH，H2 CO，NH 3，CO，C2 H2，和HC 3 N。我们还讨论了主要挥发物的空间释气，以了解它们的来源和它们之间的空间关联。46 P/Wirtanen中H2O的空间分布表明，在彗发中存在扩展的H2O释气源，类似于EPOXI目标彗星103 P/Hartley 2。46 P/Wirtanen是少数几颗已知的超活跃彗星之一，我们注意到它的成分和释气行为在许多方面与其他超活跃彗星相似。我们注意到，分析的母体挥发物显示出不同的变化（相对混合比）在显灵。我们比较了46 P/Wirtanen的化学成分与彗星家族彗星的平均丰度和彗星人口的地面近红外设施测量的日期。46 P/Wirtanen的分子丰度表明，虽然它们在变化，但与彗星种群的范围相比变化很小，与其他分子相比，CH 3OH显示出明显更多的变化。
We present a comprehensive analysis of the chemical composition of the Jupiter-family comet and potential spacecraft target 46P/Wirtanen, in the near-IR wavelength range. We used iSHELL at the NASA Infrared Telescope Facility to observe the comet on 11 pre-, near-, and postperihelion dates in 2018 December and 2019 January and February during its historic apparition. We report rotational temperatures, production rates, and mixing ratios with respect to H2O and C2H6 or 3σ upper limits of the primary volatiles H2O, HCN, CH4, C2H6, CH3OH, H2CO, NH3, CO, C2H2, and HC3N. We also discuss the spatial outgassing of the primary volatiles, to understand their sources and the spatial associations between them. The spatial profiles of H2O in 46P/Wirtanen suggest the presence of extended H2O outgassing sources in the coma, similar to the EPOXI target comet 103P/Hartley 2. 46P/Wirtanen is among the few known hyperactive comets, and we note that its composition and outgassing behavior are similar to those of other hyperactive comets in many ways. We note that the analyzed parent volatiles showed different variations (relative mixing ratios) during the apparition. We compared the chemical composition of 46P/Wirtanen with the mean abundances in Jupiter-family comets and the comet population as measured with ground-based near-IR facilities to date. The molecular abundances in 46P/Wirtanen suggest that although they were changing, the variations were small compared to the range in the comet population, with CH3OH showing notably more variation as compared to the other molecules.