Molecular line emission in HH54: a coherent view from near to far infrared
Molecular line emission in HH54: a coherent view from near to far infrared
复制标题
HH54 中的分子线发射：从近红外到远红外的相干视图
DOI：
10.1051/0004-6361:20065127
复制
发表时间：
2006
影响因子：
6.5
通讯作者：
D. Flower
中科院分区：
文献类型：
--
作者：
T. Giannini;C. McCoey;B. Nisini;S. Cabrit;A. C. O. Garatti;L. Calzoletti;L. Calzoletti;D. Flower
目标。我们详细研究了赫比格-哈罗天体HH54的红外线发射（1-200µm）。我们的数据库包括：近红外波段（1-2.5µm）的高分辨率（R ~ 9000）和低分辨率（R ~ 600）光谱数据；中红外分光光度图（5-12µm）；以及ISO卫星获得的远红外（45-200µm, R ~ 200）光谱。因此，我们提供了60多个分子特征（主要来自近红外和中红外的H2和远红外的H2O， CO和OH）和23条离子线的检测和绝对通量。方法。来自v = 0t v = 4的水平的H2线已经在最先进的冲击代码的背景下进行了解释，其输出参数被用作大速度梯度计算的输入，以解释CO， H2O和OH的FIR发射。结果。H2的发射可以解释为源自稳态j型激波或准稳态带有磁性前体的j型激波。然而，我们的多物种分析表明，只有具有磁性前驱体的j型激波模型（vshock = 18 km s−1,nH = 10 4 cm−3,B = 100µG，年龄= 400 yr）才能解释观测到的H2发射和CO和H2O谱线。这样的模型预测H2O丰度为~ 7 × 10−5，与其他与低质量原恒星相关的外流激波模型的估计一致。我们可以排除观察到的原子谱线与分子谱线在同一激波中产生的可能性，并提出论据，支持在该区域存在另一个高速的、完全解离的激波成分。最后，鉴于即将在赫歇尔卫星上安装的光谱设备，我们提供了被认为最适合诊断目的的H2O谱线的预测。
Aims. We present a detailed study of the infrared line emission (1–200 µm) in the Herbig-Haro object HH54. Our database comprises: high- (R ∼ 9000) and low- (R ∼ 600) resolution spectroscopic data in the near-infrared band (1–2.5 µm); mid-infrared spectrophotometric images (5–12 µm); and, far-IR (45–200 µm, R ∼ 200) spectra acquired with the ISO satellite. As a result, we provide the detection of and the absolute fluxes for more than 60 molecular features (mainly from H2 in the near- and mid-infrared and from H2O, CO and OH in the far-infrared) and 23 ionic lines. Methods. The H2 lines, coming from levels from v = 0t ov = 4 have been interpreted in the context of a state-of-the-art shock code, whose output parameters are adopted as input to a Large Velocity Gradient computation in order to interpret the FIR emission of CO, H2O and OH. Results. The H2 emission can be interpreted as originating in either steady-state J-type shocks or in quasi-steady J-type shocks with magnetic precursor. However, our multi-species analysis shows that only a model of a J-type shock with magnetic precursor (vshock = 18 km s −1 , nH = 10 4 cm −3 , B = 100 µG, age = 400 yr) can account for both the observed H2 emission and the CO and H2O lines. Such a model predicts a H2O abundance of ∼7 × 10 −5 , in agreement with estimations from other shock models of outflows associated with low mass protostars. We can exclude the possibility that the observed atomic lines arise in the same shock as the molecular lines, and give arguments in favour of the presence of a further high-velocity, fully dissociative shock component in the region. Finally, in view of the forthcoming spectroscopic facilities on board of the Herschel satellite, we provide predictions for H2O lines considered to be the most suitable for diagnostic purposes.