Can the Kappa-distributed Electron Energies Account for the Intensity Ratios of O ii Lines in Photoionized Gaseous Nebulae?
Can the Kappa-distributed Electron Energies Account for the Intensity Ratios of O ii Lines in Photoionized Gaseous Nebulae?
复制标题
Kappa 分布的电子能量可以解释光电离气态星云中 O ii 谱线的强度比吗？
DOI：
10.3847/1538-4357/ab9d7e
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发表时间：
2020
期刊：
影响因子：
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通讯作者：
Yong Zhang
中科院分区：
文献类型：
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作者：
Bao;Yong Zhang
在行星状星云和H II区域的研究中，一个令人烦恼的难题是基于碰撞激发线的等离子体诊断结果系统地不同于基于复合线的诊断结果。一个相当投机的解释是存在具有所谓κ能量分布的非热电子，但几乎没有观测证据来验证或反驳这一假设。本文用近似方法研究了κ分布电子对Oii复合线发射率的影响，其中κ分布电子的速率系数是通过将Maxwellian-Boltzmann速率系数与适当的权求和来计算的.结果表明，如果考虑κ分布电子，由[O iii]（λ4959 + λ5007）/λ4363比值计算的温度与由O ii λ4649/λ4089比值计算的温度相吻合。然而，估算的温度和κ值与通过比较[Oiii]（λ4959 + λ5007）/λ4363比值和氢复合谱得到的结果不一致，表明电子能量在星云区域的全球尺度上不可能遵循κ分布。然而，仅基于这一观测，我们不能肯定地排除在星云内部的某些微结构中存在κ分布电子。
A vexing puzzle in the study of planetary nebulae and H ii regions is that the plasma diagnostic results based on collisionally excited lines systematically differ from those based on recombination lines. A fairly speculative interpretation is the presence of nonthermal electrons with the so-called κ energy distributions, yet there is little observational evidence to verify or disprove this hypothesis. In this paper, we examine the influence of κ-distributed electrons on the emissivities of O ii recombination lines using an approximate method, where the rate coefficients for a κ distribution are computed by summing Maxwellian–Boltzmann rate coefficients with appropriate weights. The results show that if invoking κ-distributed electrons, the temperatures derived from the [O iii] (λ4959 + λ5007)/λ4363 ratios could coincide with those estimated from the O ii λ4649/λ4089 ratios. However, the estimated temperatures and κ values are not in agreement with those obtained through comparing the [O iii] (λ4959 + λ5007)/λ4363 ratios and the hydrogen recombination spectra, suggesting that the electron energy is unlikely to follow the κ-distributions over a global scale of the nebular regions. Nevertheless, based on this observation alone, we cannot definitely rule out the presence of κ-distributed electrons in some microstructures within nebulae.
J.H.物理化学研究所/查尔斯大学（捷克共和国）
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