标题： ISO SWS 对 NGC 6822 和 I ZW 36 中 H II 区域的观测：硫的丰度和温度波动 显示英文标题

标题： ISO SWS Observations of H II Regions in NGC 6822 and I ZW 36: Sulfur Abundances and Temperature Fluctuations

摘要： 我们报告了对NGC 6822中的H II区域哈勃V和蓝致密矮星系I Zw 36的ISO SWS红外光谱观测。利用Br alpha、[S III]在18.7和33.5微米处以及[S IV]在10.5微米处的观测，用于确定这些H II区域中的离子硫丰度。我们的观测与基于光致电离计算的S^+3丰度预测之间有相对较好的一致性，尽管存在模型高估S^+3丰度的偏差。我们强调需要更多此类观测，以使星云硫丰度的确定建立在更坚实的基础上。结合ISO观测和光学数据得出的S/O比值与从其他贫金属星系的光学测量得出的S/O比值一致。我们提出了一种新的方法，用于根据光学和红外观测线比率的同时测定星云中的温度、温度波动和丰度。我们的ISO测量的不确定性和缺乏对[S III]lambda 9532或lambda 9069的观测，无法准确确定哈勃V和I Zw 36的温度波动幅度。最后，使用合成数据，我们展示了我们新方法的诊断能力和局限性。 显示英文摘要

摘要： We report ISO SWS infrared spectroscopy of the H II region Hubble V in NGC 6822 and the blue compact dwarf galaxy I Zw 36. Observations of Br alpha, [S III] at 18.7 and 33.5 microns, and [S IV] at 10.5 microns are used to determine ionic sulfur abundances in these H II regions. There is relatively good agreement between our observations and predictions of S^+3 abundances based on photoionization calculations, although there is an offset in the sense that the models overpredict the S^+3 abundances. We emphasize a need for more observations of this type in order to place nebular sulfur abundance determinations on firmer ground. The S/O ratios derived using the ISO observations in combination with optical data are consistent with values of S/O, derived from optical measurements of other metal-poor galaxies. We present a new formalism for the simultaneous determination of the temperature, temperature fluctuations, and abundances in a nebula, given a mix of optical and infrared observed line ratios. The uncertainties in our ISO measurements and the lack of observations of [S III] lambda 9532 or lambda 9069 do not allow an accurate determination of the amplitude of temperature fluctuations for Hubble V and I Zw 36. Finally, using synthetic data, we illustrate the diagnostic power and limitations of our new method.