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首页> 外文期刊>The Astrophysical journal >THE PHYSICS AND CHEMISTRY OF SMALL TRANSLUCENT MOLECULAR CLOUDS. VII. SO~+ AND H_2S
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THE PHYSICS AND CHEMISTRY OF SMALL TRANSLUCENT MOLECULAR CLOUDS. VII. SO~+ AND H_2S

机译：小半透明分子云的物理和化学。七。 SO〜+和H_2S

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In this third paper on sulfur species, we have conducted a survey of SO~+ (two transitions) and H_2S (one transition) in our standard samples of 11 cirrus cores and 27 Clemens-Barvainis translucent objects whose structures and chemistry have been studied earlier in this series. SO~+(~2II_(1/2), J = 3/2-1/2) is seen weakly in 12 objects, while H_2S (1_(10)-1_(01)) is detected quite strongly in 31 objects. These results are modeled in terms of our previous hydrostatic equilibrium and n ～ r~(-α) structures together with other chemical and physical properties derived earlier. The typical H_2S fractional abundance is large, ～1 x 10~(-8), and increases monotonically with increasing extinction in the 1.2-2.7 mag range (edge-to-center). Thus H_2S displays the same characteristic transition between diffuse and dense cloud chemistry as do SO, SO_2, CS, HCS~+, HCO~+, and other species studied in this series. By contrast, the SO~+ abundances are small, 1 x 10~(-9), and exhibit a marginal decrease with increasing extinction. The simple ion-molecule network as used by Turner for sulfur chemistry includes the sulfur hydride species and predicts the observed parameters of SO~+ but predicts an H_2S abundance 2 orders of magnitude less than observed. Of the 10 species presently analyzed in detail in the translucent cores, H_2S is only the second (along with H_2CO) that fails to be explained in detail by quiescent cloud ion-molecule chemistry. Various catalytic models of H_2S on grains are discussed. Photocatalysis of H_2S is found capable of producing the observed abundances but only for sizable accreted mantles. Other types of surface chemistry are also successful but are close to the limits of possible efficiencies. We have detected OCS and H_2CS in one object, CB 17, with abundances of 1 x 10~(-9) and 7 x 10~(-9), respectively. Our ion-molecule model has been expanded to include OCS and H_2CS chemistry. We find that the model fits observed abundances within a factor of 3 for both species.
机译：在有关硫物质的第三篇论文中，我们对11个卷云岩核和27个Clemens-Barvainis半透明物体的标准样品中的SO〜+（两个过渡态）和H_2S（一个过渡态）进行了调查，这些物体的结构和化学性质已得到较早的研究。在这个系列中。在12个物体中微弱地看到了SO〜+（〜2II_（1/2），J = 3 / 2-1 / 2），而在31个物体中非常强烈地检测到了H_2S（1_（10）-1_（01））。这些结果是根据我们先前的静水平衡和n〜r〜（-α）结构以及较早得出的其他化学和物理性质来建模的。典型的H_2S分数丰度大，约为1 x 10〜（-8），并且在1.2-2.7 mag范围内（边缘到中心）随着消光的增加而单调增加。因此，H_2S表现出与SO，SO_2，CS，HCS〜+，HCO〜+和本系列研究的其他物种相同的在扩散云云和稠密云化学之间的特征过渡。相比之下，SO〜+的丰度很小，为1 x 10〜（-9），并且随着消光的增加而显示出少量的下降。特纳用于硫化学的简单离子分子网络包括氢化硫物质，可以预测所观测到的SO〜+参数，但可以预测H_2S丰度比观测值小2个数量级。目前在半透明核中详细分析的10个物种中，H_2S仅是第二个（以及H_2CO），无法通过静态云离子分子化学进行详细解释。讨论了H_2S在晶粒上的各种催化模型。发现H_2S的光催化能够产生所观察到的丰度，但是仅对于相当大的增生地幔。其他类型的表面化学方法也很成功，但已接近可能效率的极限。我们已经在一个物体CB 17中检测到OCS和H_2CS，其丰度分别为1 x 10〜（-9）和7 x 10〜（-9）。我们的离子分子模型已扩展为包括OCS和H_2CS化学。我们发现，该模型将两个物种的观测到的丰度拟合在3倍之内。

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