Mercapto radical (SH) in translucent interstellar clouds
Mercapto radical (SH) in translucent interstellar clouds
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DOI：
10.1051/0004-6361/201526488
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发表时间：
2015-07
影响因子：
6.5
通讯作者：
Dongfeng Zhao;G. Galazutdinov;H. Linnartz;J. Krełowski
中科院分区：
文献类型：
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作者：
Dongfeng Zhao;G. Galazutdinov;H. Linnartz;J. Krełowski
我们提出了第一次检测的旋转分辨电子跃迁的巯基自由基（SH）在近紫外半透明星际云。利用甚大望远镜的紫外和目视中阶梯摄谱仪获得的观测数据，研究了SH的近紫外吸收光谱。在SH的A →-X →（0，0）带中，在λ 3242.40和3240.66 A处的两个弱吸收特征分别被指定为P11（3/2）和（P21（3/2）+ Q11（3/2））双峰跃迁，在四条选定的视线的平均光谱中被确定：HD 73882、HD 78344、HD 80077和HD 154368。这些特征很弱，但可以在3σ检测限内识别，并且在其他已发表的数据集中也可以找到。我们编制了一组SH的线位置和振荡器强度，以方便数据分析。我们得到了SH柱密度的平均值，为1.5 ± 0.3 × 1013 cm−2，这很可能代表了单个富含SH的半透明云中SH柱密度的大小。这个值也是一致的预测模型的C型冲击和湍流耗散区与典型的半透明云的条件。
We present the first detection of rotationally resolved electronic transitions of the mercapto radical (SH) in the near-ultraviolet in translucent interstellar clouds. Observational data acquired by the Ultraviolet and Visual Echelle Spectrograph of the Very Large Telescope were used to search for the near-ultraviolet absorption spectra of SH. Two weak absorption features at ∼3242.40 and 3240.66 A, assigned as the P11(3/2) and the (P21(3/2) + Q11(3/2)) doublet transitions in the AΣ–XΠ (0, 0) band of SH, respectively, were identified in the averaged spectrum of four selected lines of sight: HD 73882, HD 78344, HD 80077, and HD 154368. These features are weak, but can be identified within a 3σ detection limit, and are found in other published data sets as well. We compiled a set of line positions and oscillator strengths of SH to facilitate the data analysis. We derived an averaged value of the SH column density, ∼1.5 ± 0.3 × 1013 cm−2, that is most likely representative for the magnitude of SH column densities in individual SH-rich translucent clouds. This value is also consistent with predictions from models for C-type shocks and turbulent dissipation regions with typical translucent cloud conditions.