Detection of [O I] λ6300 and Other Diagnostic Emission Lines in the Diffuse Ionized Gas of M33 with Gemini-North
Detection of [O I] λ6300 and Other Diagnostic Emission Lines in the Diffuse Ionized Gas of M33 with Gemini-North
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DOI：
10.1086/505575
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发表时间：
2006-05
期刊：
影响因子：
--
通讯作者：
E. Voges;R. Walterbos
中科院分区：
文献类型：
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作者：
E. Voges;R. Walterbos
本文介绍了在M33中靠近NGC 604的H II区的扩散电离气体（DIG）的光谱观测结果。我们首次在M33的DIG中探测到[O I] λ6300，这是区分光电离和冲击电离模型的关键线之一。我们测量的[O I]/Hα在0.04-0.10的范围内，并且随着排放量的减少，该比率增加。我们的[S II]/Hα和[N II]/Hα的测量值也随着发射测量值的减小而增加，而我们的[O III]/Hβ的测量值保持相当恒定。我们在最亮的发射测量区域有一个He I的试探性探测，He I/Hα = 0.033 ± 0.019，表明氦至少部分电离。我们比较我们观察到的发射线比光电离模型，发现场星星电离模型不适合我们的数据。泄漏H II区模型与我们的数据是一致的，而不需要调用额外的电离机制，以适应我们的[O I]或[O III]测量。最近的大H II区是NGC 604，因此可能是该区域气体电离光子的来源。
We present spectroscopic observations of diffuse ionized gas (DIG) in M33 near the H II region NGC 604. We present the first detection of [O I] λ6300 in the DIG of M33, one of the critical lines for distinguishing photoionization from shock ionization models. We measure [O I]/Hα in the range of 0.04-0.10 and an increase in this ratio with decreasing emission measure. Our measurements of [S II]/Hα and [N II]/Hα also rise with decreasing emission measure, while our [O III]/Hβ measurements remain fairly constant. We have one tentative detection of He I in the region of brightest emission measure, with a ratio of He I/Hα = 0.033 ± 0.019, indicating that the helium is at least partially ionized. We compare our observed emission-line ratios to photoionization models and find that field star ionization models do not fit our data well. Leaky H II region models are consistent with our data, without the need to invoke additional ionization mechanisms to fit our [O I] or [O III] measurements. The closest large H II region is NGC 604 and is therefore a likely candidate for the source of the ionizing photons for the gas in this region.