The interstellar N2 abundance towards HD 124314 from far-ultraviolet observations
The interstellar N2 abundance towards HD 124314 from far-ultraviolet observations
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DOI：
10.1038/nature02614
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发表时间：
2004-06
期刊：
影响因子：
64.8
通讯作者：
D. Knauth;B. Andersson;S. McCandliss;W. Moos
中科院分区：
文献类型：
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作者：
D. Knauth;B. Andersson;S. McCandliss;W. Moos
星际分子氮（N2）的丰度具有相当重要的意义：稳态气相星际化学模型，结合致密分子云中星际N2H+的毫米波长观测，预测N2应该是星际介质中最丰富的含氮分子。以前探测远紫外线或红外线（冰的特征）吸收n2的尝试迄今为止都没有成功。在这里，我们报告了对半人马座中中度变红的恒星HD 124314的远紫外波长星际n2的探测。n2柱密度大于漫射云模型的预期值，而明显小于密集分子云模型的预期值。此外，n2丰度并不能解释观测到的原子氮丰度（N I）在高柱密度视线上的变化，这意味着星际介质中氮化学的模型是不完整的。
The abundance of interstellar molecular nitrogen (N2) is of considerable importance: models of steady-state gas-phase interstellar chemistry,, together with millimetre-wavelength observations,of interstellar N2H+in dense molecular clouds predict that N2should be the most abundant nitrogen-bearing molecule in the interstellar medium. Previous attempts to detect N2absorption in the far-ultraviolet or infrared (ice features) have hitherto been unsuccessful. Here we report the detection of interstellar N2at far-ultraviolet wavelengths towards the moderately reddened star HD 124314 in the constellation of Centaurus. The N2column density is larger than expected from models of diffuse clouds and significantly smaller than expected for dense molecular clouds. Moreover, the N2abundance does not explain the observed variations in the abundance of atomic nitrogen (N I) towards high-column-density sightlines, implying that the models of nitrogen chemistry in the interstellar medium are incomplete.