First Detection of 13CH+ (J = 1-0)
First Detection of 13CH+ (J = 1-0)
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第一次检测13CH (J = 1-0)
DOI：
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发表时间：
2005
期刊：
影响因子：
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通讯作者：
J. Pearson
中科院分区：
文献类型：
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作者：
E. Falgarone;T. Phillips;J. Pearson
我们报告了在G10.6-0.4明亮恒星形成区域的尘埃连续辐射吸收中可能检测到13CH+(1-0)线。如果13CH+线速度质心是吸收中看到的H I气体的质心，则我们确定的其余频率为830.132(3)GHz。这将与12CH+(1-0)的新直接光谱实验室测量和从12CH+(1-0)缩放到13CH+(1-0)得出的830.131 GHz值进行比较。然而，如果13CH+线起源于恒星形成区，或者起源于12CO（1-0）发射的中间分子气体，则推断出的休息频率分别为830.107(1)GHz或830.193(4)GHz，明显超出了预测范围。因此，我们得出结论，13CH+谱线产生于一种气相，这种气相没有被12CO（1-0）谱线所追踪到，而是含有大柱密度的冷H I和丰富到足以形成CH+的H2。这些性质是冷中性介质的性质。推断柱密度为N(13CH+) = × 1012 cm-2，对应于同位素丰度比[12CH+]/[13CH+] = 40时N(CH+) = × 1013 cm-2。通过对原子气体H2含量的一些假设，我们估计了在这个速度范围内的总氢柱密度，并发现相对于H的CH+丰度大约是太阳附近的两倍，这是由光学吸收谱线得出的。
We report the probable detection of the 13CH+ (1-0) line in absorption against the dust continuum emission of a bright star-forming region, G10.6-0.4. If the 13CH+ line velocity centroid is that of the H I gas seen in absorption, the rest frequency we determine is 830.132(3) GHz. This is to be compared to the value of 830.131 GHz derived from new direct spectroscopy laboratory measurements of 12CH+ (1-0) and scaling from 12CH+ (1-0) to 13CH+ (1-0). However, if the 13CH+ line originated in either the star-forming region or in the intervening molecular gas as traced by 12CO (1-0) emission, then the inferred rest frequency would be 830.107(1) or 830.193(4) GHz, respectively, both clearly out of the predicted range. We thus conclude that the 13CH+ line arises in a gas phase not traced by the 12CO (1-0) line but one containing a large column density of cold H I and rich enough in H2 to form CH+. Such properties are those of the cold neutral medium. The inferred column density is N(13CH+) = × 1012 cm-2, corresponding to N(CH+) = × 1013 cm-2 for an isotopic abundance ratio [12CH+]/[13CH+] = 40. With some assumptions concerning the H2 content of the atomic gas, we estimate the total hydrogen column density in this velocity range and find a CH+ abundance relative to H about twice that in the solar neighborhood, as derived from optical absorption lines.