We present high-resolution (R = 75,000-100,000) mid-infrared spectra of the high-mass embedded young star IRS 1 in the NGC 7538 star-forming region. Absorption lines from many rotational states of C2H2, 13C12CH2, CH3, CH4, NH3, HCN, HNCO, and CS are seen. The gas temperature, column density, covering factor, line width, and Doppler shift for each molecule are derived. All molecules were fit with two velocity components between –54 and –63 km s–1. We find high column densities (~1016 cm–2) for all the observed molecules compared to values previously reported and present new results for CH3 and HNCO. Several physical and chemical models are considered. The favored model involves a nearly edge-on disk around a massive star. Radiation from dust in the inner disk passes through the disk atmosphere, where large molecular column densities can produce the observed absorption line spectrum.
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机译：我们介绍了NGC 7538星形成区中高质量嵌入式年轻恒星IRS 1的高分辨率（R = 75,000-100,000）中红外光谱。可以看到来自C2H2、13C12CH2，CH3，CH4，NH3，HCN，HNCO和CS的许多旋转状态的吸收线。推导出每个分子的气体温度，柱密度，覆盖因子，线宽和多普勒频移。所有分子都具有介于–54和–63 km s–1之间的两个速度分量。我们发现，与先前报道的值相比，所有观察到的分子均具有较高的柱密度（〜1016 cm–2），并提供了CH3和HNCO的新结果。考虑了几种物理和化学模型。最受青睐的模型包括围绕着巨大恒星的近边缘盘。内部磁盘中灰尘的辐射穿过磁盘大气，在大气中较大的分子列密度可产生观察到的吸收线光谱。
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