Iron abundance in HII regions
Iron abundance in HII regions
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HII 区域的铁丰度
DOI：
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发表时间：
2002
期刊：
影响因子：
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通讯作者：
M. Rodríguez
中科院分区：
文献类型：
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作者：
M. Rodríguez
光学CCD光谱被用来确定$元素{Fe}$丰度在几个位置内七个明亮的银河系HII地区。所观察到的[$离子{Fe}{iii}$]线比进行比较，该离子的碰撞强度和跃迁概率的不同集合的预测，以选择提供最佳拟合的观测原子数据。从光电离模型的网格中得到的元素[++]{Fe}$和元素[+]{Fe}$丰度值，以及元素[3+]{Fe}$贡献的电离校正因子，沿着，意味着电离气体中Fe/O比在太阳的2%到30%之间。的$元素{Fe}$丰度推导出的每个区域都与电离度和颜色过剩。一个可能的解释是，即存在的人口的小颗粒，可能源于破碎较大的颗粒。这些小颗粒在吸收高能光子后会将元素Fe原子释放到气体中;在这一破坏过程中幸存下来的小颗粒会被辐射压或恒星风的作用从电离区中扫出。一个进一步和更有效的销毁剂的指示是由高$元素{Fe}$丰度得出的一个位置采样的光学射流H 399在M 20，在那里灰尘销毁由于冲击波可能发生。
Optical CCD spectra are used to determine the $element{Fe}$ abundances at several positions inside seven bright Galactic HII regions. The observed [$ion{Fe}{iii}$] line ratios are compared with the predictions of different sets of collision strengths and transition probabilities for this ion to select the atomic data providing the best fit to the observations. The values found for the $element[++]{Fe}$ and $element[+]{Fe}$ abundances, along with ionization correction factors for the contribution of $element[3+]{Fe}$, obtained from available grids of photoionized models, imply that the Fe/O ratio in the ionized gas is between 2% and 30% of solar. The $element{Fe}$ abundances derived for each area are correlated both with the degree of ionization and the colour excess. A possible explanation is suggested, namely the presence of a population of small grains, probably originating from the fragmentation of larger grains. These small grains would release $element{Fe}$ atoms into the gas after the absorption of energetic photons; the small grains surviving this destruction process would be swept out of the ionized region by the action of radiation pressure or stellar winds. An indication of a further and more efficient destruction agent is given by the high $element{Fe}$ abundance derived for a position sampling the optical jet H 399 in M 20, where dust destruction due to shock waves has presumably taken place.