Infrared emission and the destruction of dust in HII regions
Infrared emission and the destruction of dust in HII regions
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HII 地区的红外发射和粉尘破坏
DOI：
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发表时间：
2013
期刊：
影响因子：
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通讯作者：
D. Wiebe
中科院分区：
文献类型：
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作者：
Y. Pavlyuchenkov;M. Kirsanova;D. Wiebe
研究了一颗年轻大质量恒星周围电离氢区8、24和100µm波段红外辐射的产生和红外强度分布。采用自一致的化学动力学模型处理HII区域的演化，其中包括三种粉尘种群-大硅酸盐颗粒，小石墨颗粒和多环芳烃（PAHs）。采用考虑小颗粒和大分子随机加热的辐射传递模型来模拟红外光谱能量分布。计算结果与斯皮策和赫歇尔对RCW 120星云的观测结果进行了比较。研究了气体粒子碰撞和恒星辐射场对小颗粒随机加热的贡献。结果表明，具有均匀多环芳烃含量的模型不能再现8µm处的环状红外强度分布。多环芳烃被恒星的紫外线辐射破坏的模型，产生HII区域，提供了一种解释这种强度分布的方法。该模型与多环芳烃的实际特征破坏时间的观测结果一致。
The generation of infrared (IR) radiation and the observed IR-intensity distribution at wavelengths of 8, 24, and 100 µm in the ionized hydrogen region around a young, massive star is investigated. The evolution of the HII region is treated using a self-consistent chemical-dynamical model in which three dust populations are included—large silicate grains, small graphite grains, and polycyclic, aromatic hydrocarbons (PAHs). A radiative transfer model taking into account stochastic heating of small grains and macromolecules is used to model the IR spectral energy distribution. The computational results are compared with Spitzer and Herschel observations of the RCW 120 nebula. The contributions of collisions with gas particles and the radiation field of the star to stochastic heating of small grains are investigated. It is shown that a model with a homogeneous PAH content cannot reproduce the ring-like IR-intensity distribution at 8 µm. A model in which PAHs are destroyed by ultraviolet radiation of the star, generating region HII, provides a means to explain this intensity distribution. This model is in agreement with observations for realistic characteristic destruction times for the PAHs.