arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2005.14118astro-ph.GAastro-ph.SR
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对高质量恒星形成区的DC $_3$ N观测

DC$_3$N observations towards high-mass star-forming regions

V. M. Rivilla, L. Colzi, F. Fontani, M. Melosso, P. Caselli, L. Bizzocchi, F. Tamassia, L. Dore

摘要:

我们目前的研究氘代氰乙炔(HC $_3$ N)对样本的28个高质量恒星形成的核心分为不同的演化阶段,从无星演化的原恒星核心。我们报告的第一次检测到DC $_3$ N对15个高质量的核心。DC $_3$ N与HC $_3$ N的丰度比在0.003-$-$-0.022之间,低于低质量原恒星和暗星云中的丰度比。我们比较了HC $_3$ N的氘代水平与同一样品中其他分子的氘代水平,发现与仅在气相中形成或主要在气相中形成的物种的相关性较弱(分别为N $_2$、H $^+$和HNC),与仅在或主要在尘埃颗粒上形成的物种没有相关性(分别为CH $_3$ OH和NH $_3$)。我们还提出了一个单碟的DC $_3$ N对原星团IRAS 05358+3543的地图,这表明DC $_3$ N的痕迹扩展信封($\sim$ 0.37 pc)和峰值向两个冷凝聚分离的位置的原恒星和尘埃连续。在这项工作中提出的意见表明,氘的HC $_3$ N产生的气体中的寒冷的外部部分的大规模恒星形成的团块,给我们一个估计的氘的因素之前,形成更密集的气体。

英文摘要:

We present the study of deuteration of cyanoacetylene (HC$_3$N) towards a sample of 28 high-mass star-forming cores divided into different evolutionary stages, from starless to evolved protostellar cores. We report for the first time the detection of DC$_3$N towards 15 high-mass cores. The abundance ratios of DC$_3$N with respect HC$_3$N range in the interval 0.003$-$0.022, lower than those found in low-mas protostars and dark clouds. No significant trend with the evolutionary stage, or with the kinetic temperature of the region, has been found. We compare the level of deuteration of HC$_3$N with those of other molecules towards the same sample, finding weak correlation with species formed only or predominantly in gas phase (N$_2$H$^+$ and HNC, respectively), and no correlation with species formed only or predominantly on dust grains (CH$_3$OH and NH$_3$, respectively). We also present a single-dish map of DC$_3$N towards the protocluster IRAS 05358+3543, which shows that DC$_3$N traces an extended envelope ($\sim$0.37 pc) and peaks towards two cold condensations separated from the positions of the protostars and the dust continuum. The observations presented in this work suggest that deuteration of HC$_3$N is produced in the gas of the cold outer parts of massive star-forming clumps, giving us an estimate of the deuteration factor prior to the formation of denser gas.

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