Shock chemistry in the young bipolar outflow L1157
Shock chemistry in the young bipolar outflow L1157
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DOI：
10.1086/310877
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发表时间：
1997-09-20
影响因子：
4.9
通讯作者：
Gutierrez, MP
中科院分区：
文献类型：
--
作者：
Bachiller, R;Gutierrez, MP
我们提出的第一个结果，从最近的调查分子线在L1157，一个高度准直的双极分子外流驱动的0类原恒星。这些观测被用来研究由剧烈的、高度准直的外流所产生的化学变化。观察到不同的分子谱线以追踪气体的不同组分。一些分子（C3 H2，N2 H+，（HCO+）-C-13，DCO+）在静止介质中是丰富的，但在高速下没有观察到。来自这些分子的谱线是原恒星周围致密气体浓度的最佳示踪剂。此外，我们发现一些其他罕见的分子（例如，SiO、CH 3OH、H2 CO、HCN、CN、SO和SO2）在冲击区域被增强至少一个数量级。我们的观察提供了这些物种的增强因子的估计。沿着流出蓝色叶观察到化学成分的强梯度，这可能是由于化学过程的时间演变。我们简要地讨论了最重要的分子的化学性质，特别关注被认为是丰富的星际冰地幔中的物种。
We present the first results from a recent survey of molecular lines in L1157, a highly collimated bipolar molecular outflow driven by a class 0 protostar. These observations are used to study the chemical alterations produced by a violent, highly collimated outflow. Different molecular lines are observed to trace different components of the gas. Some molecules (C3H2, N2H+, (HCO+)-C-13, DCO+) are abundant in the quiescent medium but are not observed at high velocities. Lines from these molecules are the best tracers of the concentration of dense gas around the protostar. In addition, we find that some otherwise rare molecules (e.g., SiO, CH3OH, H2CO, HCN, CN, SO, and SO2) are enhanced by at least an order of magnitude at the shocked region. Our observations provide estimates of the enhancement factors for such species. Strong gradients in the chemical composition are observed along the outflow blue lobe, which could be due to the evolution in time of the chemical processes. We briefly discuss the chemistry of the most important molecules, devoting special attention to the species that are thought to be abundant in interstellar ice mantles.