TMC-1中的硫元素传奇：HCSCN和HCSCCH的发现
The sulphur saga in TMC-1: Discovery of HCSCN and HCSCCH.
作者信息
Cernicharo J, Cabezas C, Endo Y, Agúndez M, Tercero B, Pardo J R, Marcelino N, de Vicente P
机构信息
Grupo de Astrofísica Molecular, Instituto de Física Fundamental (IFF-CSIC), C / Serrano 121, 28006 Madrid, Spain.
Department of Applied Chemistry, Science Building II, National Yang Ming Chiao Tung University, 1001 Ta-Hsueh Rd., Hsinchu 30010, Taiwan.
出版信息
Astron Astrophys. 2021 Jun 23;650. doi: 10.1051/0004-6361/202141297. eCollection 2021 Jun.
We report the detection, for the first time in space, of cyano thioformaldehyde (HCSCN) and propynethial (HCSCCH) towards the starless core TMC-1. Cyano thioformaldehyde presents a series of prominent - and -type lines, which are the strongest previously unassigned features in our Q-band line survey of TMC-1. Remarkably, HCSCN is four times more abundant than cyano formaldehyde (HCOCN). On the other hand, HCSCCH is five times less abundant than propynal (HCOCCH). Surprisingly, we find an abundance ratio HCSCCH/HCSCN of ∼ 0.25, in contrast with most other ethynyl-cyanide pairs of molecules for which the CCH-bearing species is more abundant than the CN-bearing one. We discuss the formation of these molecules in terms of neutral-neutral reactions of S atoms with CHCCH and CHCN radicals as well as of CCH and CN radicals with HCS. The calculated abundances for the sulphur-bearing species are, however, significantly below the observed values, which points to an underestimation of the abundance of atomic sulphur in the model or to missing formation reactions, such as ion-neutral reactions.
我们首次在太空中检测到朝向无恒星核心TMC-1的氰基硫甲醛（HCSCN）和丙炔硫醛（HCSCCH）。氰基硫甲醛呈现出一系列突出的 - 型谱线，这些是我们对TMC-1进行Q波段谱线普查中最强的先前未归属特征。值得注意的是，HCSCN的丰度比氰基甲醛（HCOCN）高四倍。另一方面，HCSCCH的丰度比丙炔醛（HCOCCH）低五倍。令人惊讶的是，我们发现HCSCCH/HCSCN的丰度比约为0.25，这与大多数其他乙炔基 - 氰化物分子对形成对比，在那些分子对中，含CCH的物种比含CN的物种更丰富。我们根据S原子与CHCCH和CHCN自由基以及CCH和CN自由基与HCS的中性 - 中性反应来讨论这些分子的形成。然而，计算出的含硫物种的丰度明显低于观测值，这表明模型中原子硫的丰度被低估，或者存在缺失的形成反应，如离子 - 中性反应。
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