论文标题
紫外线线排放的光化学模型在67p/churyumov-gerasimenko的内部昏迷中
A photochemical model of ultraviolet atomic line emissions in the inner coma of comet 67P/Churyumov-Gerasimenko
论文作者
论文摘要
Alice Ultraviolet光谱仪在板载Rosetta太空任务上观察到来自彗星67p/Churyumov-Gerasimenko挥发性物种发出的几种光谱排放（在整个护送阶段，在67p/c-g之后听到）。我们已经开发了一种用于研究原子氢（HI 1216、1025和973 ANG）的光化学模型，氧气（OI 1152、1304和1356 ANG）和碳（CI 1561＆1657 ANG）线条线的排放是通过重大生产途径来计算的。开发的模型已用于计算这些线的发射强度，这是核中心投影距离的函数，以及通过改变输入参数，即中性丰度和横截面来计算Nadir视图。我们已经量化了光子和电子影响分离激发过程对发射线的总强度的百分比贡献，这对于分析爱丽丝观察到的光谱具有重要意义。发现在67p/c-g中，中性气体产量约为10 $^{27} $ s $^{ - 1} $，当时它是1.56 au，来自太阳的1.56 au，与确定原子发射量的电子影响相比，光电疗养的激发过程比较明显。 Based on our model calculations, we suggest that the observed atomic hydrogen, oxygen, and carbon emission intensities can be used to derive H$_2$O, O$_2$, and CO, abundances, respectively, rather than electron density in the coma of 67P/C-G, when the comet has a gas production rate of $\ge$ 10$^{27}$ s$^{-1}$.
Alice ultraviolet spectrometer onboard Rosetta space mission observed several spectroscopic emissions emanated from volatile species of comet 67P/Churyumov-Gerasimenko (hear after 67P/C-G) during its entire escorting phase. We have developed a photochemical model for comet 67P/C-G to study the atomic hydrogen (HI 1216, 1025, & 973 Ang), oxygen (OI 1152, 1304, & 1356 Ang), and carbon (CI 1561 & 1657 Ang) line emissions by accounting for major production pathways. The developed model has been used to calculate the emission intensities of these lines as a function of nucleocentric projected distance and also along with the nadir view by varying the input parameters, viz., neutral abundances and cross sections. We have quantified the percentage contributions of photon and electron impact dissociative excitation processes to the total intensity of the emission lines, which has important relevance for the analysis of Alice observed spectra. It is found that in comet 67P/C-G, which is having a neutral gas production rate of about 10$^{27}$ s$^{-1}$ when it was at 1.56 AU from the Sun, photodissociative excitation processes are more significant compared to electron impact reactions in determining the atomic emission intensities. Based on our model calculations, we suggest that the observed atomic hydrogen, oxygen, and carbon emission intensities can be used to derive H$_2$O, O$_2$, and CO, abundances, respectively, rather than electron density in the coma of 67P/C-G, when the comet has a gas production rate of $\ge$ 10$^{27}$ s$^{-1}$.
