论文标题
彗星昏迷的Sublime 3D型号：高音丰富的彗星C/2016 R2（PANSTARRS）
A SUBLIME 3D Model for Cometary Coma Emission: the Hypervolatile-Rich Comet C/2016 R2 (PanSTARRS)
论文作者
论文摘要
彗星C/2016 R2（PANSTARRS）的昏迷是有史以来最奇特的昏迷之一，尤其是由于其极高的CO/H2O和N2+/H2O比}，并且是不寻常的痕量挥发性丰度。但是，其CO发射线的复杂形状以及昏迷结构和激发的不确定性导致了CO总生产率的歧义。我们使用James Clerk Maxwell望远镜（JCMT）和亚毫升阵列（SMA）进行了高分辨率，空间，光谱和时间分辨的CO观测值，以阐明C/2016 R2的量化行为。使用新的，时间依赖的三维辐射传输代码（Sublime）对结果进行分析，该结果首次合并了Co-CO系统的准确状态到状态碰撞率系数。 The total CO production rate was found to be in the range $(3.8-7.6)\times10^{28}$ s$^{-1}$ between 2018-01-13 and 2018-02-01, with a mean value of $(5.3\pm0.6)\times10^{28}$ s$^{-1}$ at r_H = 2.8-2.9 au.该排放集中在近弯的喷气机中，流速速度$ 0.51 \ pm0.01 $ km/s，而$ 0.25 \ pm0.01 $ km/s/s的环境（和夜间）昏迷。还发现了CO发射的扩展来源的证据，这可能是由于冰冻的晶粒升华约为$ 1.2 \ times10^5 $ km，距离核。基于昏迷的分子丰度，我们建议将C/2016 R2的核芯分为迅速升华的偏振相，富含CO，CO2，N2和CH3OH，并且主要冷冻（或较少的丰富），极性相位，含有更多的H2O，CH4，CH4，H2CO和HCN。
The coma of comet C/2016 R2 (PanSTARRS) is one of the most chemically peculiar ever observed, in particular due to its extremely high CO/H2O and N2+/H2O ratios}, and unusual trace volatile abundances. However, the complex shape of its CO emission lines, as well as uncertainties in the coma structure and excitation, has lead to ambiguities in the total CO production rate. We performed high resolution, spatially, spectrally and temporally resolved CO observations using the James Clerk Maxwell Telescope (JCMT) and Submillimeter Array (SMA) to elucidate the outgassing behaviour of C/2016 R2. Results are analyzed using a new, time-dependent, three dimensional radiative transfer code (SUBLIME), incorporating for the first time, accurate state-to-state collisional rate coefficients for the CO--CO system. The total CO production rate was found to be in the range $(3.8-7.6)\times10^{28}$ s$^{-1}$ between 2018-01-13 and 2018-02-01, with a mean value of $(5.3\pm0.6)\times10^{28}$ s$^{-1}$ at r_H = 2.8-2.9 au. The emission is concentrated in a near-sunward jet, with an outflow velocity $0.51\pm0.01$ km/s, compared to $0.25\pm0.01$ km/s in the ambient (and night-side) coma. Evidence was also found for an extended source of CO emission, possibly due to icy grain sublimation around $1.2\times10^5$ km from the nucleus. Based on the coma molecular abundances, we propose that the nucleus ices of C/2016 R2 can be divided into a rapidly sublimating apolar phase, rich in CO, CO2, N2 and CH3OH, and a predominantly frozen (or less abundant), polar phase containing more H2O, CH4, H2CO and HCN.
