Infrared Space Observatory Mid-Infrared Spectra of Reflection Nebulae
Infrared Space Observatory Mid-Infrared Spectra of Reflection Nebulae
复制标题
红外空间观测站反射星云的中红外光谱
DOI：
10.1086/308379
复制
发表时间：
2000
期刊：
影响因子：
--
通讯作者：
M. Houdashelt
中科院分区：
文献类型：
--
作者：
K. Uchida;K. Sellgren;M. Werner;M. Houdashelt
本文介绍了用红外空间天文台（ISO）上的红外相机和圆形可变滤光轮对反射星云vdB 17（NGC 1333）、vdB 59（NGC 2068）、vdB 101、vdB 111、vdB 133和vdB 135进行的5-15 μm成像光谱。这些星云被Teff = 3，600 - 19，000 K的恒星所照亮，这意味着紫外线（λ < 400 nm）与恒星总流量的比率为F（λ<400 nm）/Ftotal = 0.01-0.87。我们探测到星际介质在6.2、7.7、8.6、11.3和12.7 μm的红外发射特征（IEFs），在6-9 μm和11-13 μm的宽发射特征，以及5-15 μm的连续发射特征，分别为vdB 17、vdB 59和vdB 133（F（λ<400 nm）/Ftotal = 0.22-0.87），星际介质发射的上限为vdB 101、vdB 111和vdB 135（F（λ<400 nm）/Ftotal = 0.01-0.20）。我们的目标是测试模型的预测归因于多环芳烃（PAHs）的IEFs。星际模型预测多环芳烃的变化，从单电离到中性的紫外线强度，G 0，降低。6-10 μm的多环芳烃排放量与10-14 μm的多环芳烃排放量之比预计在电离多环芳烃中比在中性多环芳烃中高10倍。我们没有观察到不同的Teff的光谱差异。我们分析的频谱vdB 17和vdB 59作为一个函数的距离，从星星，看看如何频谱取决于G 0内的每个源。我们发现的唯一定量差异是7.7 μm IEF在G 0 = 20-60时在vdB 17范围内变宽。在G 0 = 20-6 × 104时，我们只观察到6-10 μm与10-14 μm通量比的40%变化。
We present 5-15 μm imaging spectroscopy of the reflection nebulae vdB 17 (NGC 1333), vdB 59 (NGC 2068), vdB 101, vdB 111, vdB 133, and vdB 135, obtained with the infrared camera and circular variable filter wheel on the Infrared Space Observatory (ISO). These nebulae are illuminated by stars with Teff = 3,600-19,000 K, implying UV (λ < 400 nm) to total stellar flux ratios of F(λ<400 nm)/Ftotal = 0.01-0.87. We detect the infrared emission features (IEFs) at 6.2, 7.7, 8.6, 11.3, and 12.7 μm, broad emission features at 6-9 μm and 11-13 μm, and 5-15 μm continuum emission, from the interstellar medium in vdB 17, vdB 59, and vdB 133 (F(λ<400 nm)/Ftotal = 0.22-0.87), and place upper limits on the emission from the interstellar medium in vdB 101, vdB 111, and vdB 135 (F(λ<400 nm)/Ftotal = 0.01-0.20). Our goal is to test predictions of models attributing the IEFs to polycyclic aromatic hydrocarbons (PAHs). Interstellar models predict PAHs change from singly ionized to neutral as the UV intensity, G0, decreases. The ratio of PAH emission at 6-10 μm to PAH emission at 10-14 μm is expected to be 10 times higher in ionized than in neutral PAHs. We observe no spectroscopic differences with varying Teff. We analyze the spectra of vdB 17 and vdB 59 as a function of distance from the star to see how the spectra depend on G0 within each source. The only quantitative difference we find is a broadening of the 7.7 μm IEF at G0 = 20-60 within vdB 17. We observe only a 40% change in the 6-10 μm to 10-14 μm flux ratio over G0 = 20-6 × 104.