标题： 早期恒星形成核样本中的含硫分子 显示英文标题

标题： Sulfur-bearing molecules in a sample of early star-forming cores

摘要： 星际介质中密集分子区域的硫含量与弥漫云相比明显减少，这种现象的原因尚不清楚，因此有必要对密集区域（主要是在早期演化阶段）的含硫物种进行观测研究，以揭示早期硫化学。利用阿塔卡马大型毫米波/亚毫米波阵列（ALMA）数据档案中的数据，我们调查了来自ATLASGAL巡天中最庞大红外安静分子团块中的37个密集核样本。分析了34SO、SO2、NS、SO、SO+和H2CS这六种谱线，并获得了每种分子物种的柱密度。从连续谱发射和两条CH3OH谱线中，我们对37个核心进行了密度和温度特征化，并推导出相应的H2柱密度。得到了这些含硫物种的丰度并进行了研究。我们发现，所分析物种的丰度随着气体温度的升高而增加，表明参与形成每种分析分子的化学反应可能在Tk为20到100K的范围内具有相似的依赖性。我们还发现，丰度之间的比较通常高度相关。鉴于这种相关性在更进化的源中降低，我们建议这里分析的含硫物种应具有类似的化学起源。根据测量到的线宽，我们指出含有氧元素的分子（34SO、SO2、SO和SO+）可能与比其他分子更温暖且湍动更强的气体有关。H2CS和NS则与更平静的气体有关，可能位于核心的外部包层中。这项工作提供了关于丰度的定量信息，这对解释星际介质中硫化学的化学模型可能是有用的。 显示英文摘要

摘要： The sulfur content in dense molecular regions of the interstellar medium is highly depleted in comparison to diffuse clouds. The reason of this phenomenon is unclear, thus it is necessary to carry out observational studies of sulfur-bearing species towards dense regions, mainly at early evolutive stages to uncover the early sulfur chemistry. Using data from the Atacama Large Millimeter Array (ALMA) data archive, we investigated a sample of 37 dense cores embedded in the most massive infrared-quiet molecular clumps from the ATLASGAL survey. Lines of 34SO, SO2, NS, SO, SO+, and H2CS were analyzed and column densities of each molecular species were obtained. From the continuum emission, and two CH3OH lines, the 37 cores were characterized in density and temperature, and the corresponding H2 column densities were derived. The abundances of such sulfur-bearing species were derived and studied. We find that the abundances of the analyzed species increase with the growth of the gas temperature, suggesting that the chemistry involved in the formation of each of the analyzed molecule may have a similar dependence with Tk in the range 20 to 100 K. We find that the comparisons among abundances are, in general, highly correlated. Given that such correlation decreases in more evolved sources, we suggest that the sulfur-bearing species here analyzed should have a similar chemical origin. From the measured line widths we point out that molecules with oxygen content (34SO, SO2, SO, and SO+) may be associated with warmer and more turbulent gas than the other ones. H2CS and NS are associated with more quiescent gas, probably in the external envelopes of the cores. This work gives quantitative information about abundances that could be useful in chemical models pointing to explain the sulfur chemistry in the interstellar medium.