We present the results of a single-pointing survey of 207 dense cores embedded in Planck Galactic Cold Clumps distributed in five different environments ( λ Orionis, Orion A, Orion B, the Galactic plane, and high latitudes) to identify dense cores on the verge of star formation for the study of the initial conditions of star formation. We observed these cores in eight molecular lines at 76–94 GHz using the Nobeyama 45 m telescope. We find that early-type molecules (e.g., CCS) have low detection rates and that late-type molecules (e.g., N 2 H + and c-C 3 H 2 ) and deuterated molecules (e.g., N 2 D + and DNC) have high detection rates, suggesting that most of the cores are chemically evolved. The deuterium fraction (D/H) is found to decrease with increasing distance, indicating that it suffers from differential beam dilution between the D/H pair of lines for distant cores (>1 kpc). For λ Orionis, Orion A, and ...

中文翻译：

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高氘分数的分子云核：Nobeyama单点调查

我们提出了单点调查的结果，该调查针对嵌入在五个不同环境（λOrionis，Orion A，Orion B，Galactic平面和高纬度）中的普朗克银河冷块中的207个密实核，以识别边缘处的密实核研究恒星形成的初始条件。我们使用Nobeyama 45 m望远镜在76–94 GHz的八个分子线中观察了这些核心。我们发现，早期类型的分子（例如CCS）检测率较低，晚期类型的分子（例如N 2 H +和cC 3 H 2）和氘代分子（例如N 2 D +和DNC）具有较高的检测率。检出率高，表明大多数核都是化学演化的。发现氘分数（D / H）随着距离的增加而降低，表示它在D / H线对之间对于远距离纤芯（> 1 kpc）受到差分光束稀释的影响。对于λOrionis，Orion A和...