The Outflow from the Luminous Young Stellar Object IRAS 20126+4104: From 4000 AU to 0.4 pc
The Outflow from the Luminous Young Stellar Object IRAS 20126+4104: From 4000 AU to 0.4 pc
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DOI：
10.1086/522919
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发表时间：
2007-12
期刊：
影响因子：
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通讯作者：
Yu-Nung Su;Sheng-Yuan Liu;H. Chen;Qizhou Zhang;R. Cesaroni
中科院分区：
文献类型：
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作者：
Yu-Nung Su;Sheng-Yuan Liu;H. Chen;Qizhou Zhang;R. Cesaroni
我们使用亚毫米阵列在 CO (3-2)、HCN (4-3) 和 SiO (5-4) 中以 1''-2'' 分辨率在距中心驱动源半径约 20'' 的半径内对发光年轻恒星物体 IRAS 20126+4104 (I20126) 的流出物进行了成像。我们的观测揭示了流出气体的至少三种不同成分：（1）朝向中央年轻恒星物体的致密（~4000 AU）双极流出。该组件的动态时间尺度约为 120 年，代表了 I20126 中非常新的喷射/流出活动。 (2) 先前在 SiO (2-1) 中检测到的准直流出物范围约为 0.2 pc。形态和运动学都支持该组件成为喷气驱动的弓激波系统。 (3) S 形 CO 流出，范围约为 0.4 pc。该组件很好地记录了进动历史。它的运动学特征（速度随着距 YSO 的距离而增加）表明，与其他证据无关，流出轴正在向天空平面移动。三个流出分量记录了初级射流进动的历史，尺度范围从几百天文单位到大约 0.4 pc。我们的结果表明 CO (3-2) 排放是探测主射流的良好示踪剂。 I20126 冲击中的气体密度和 SiO2 相对丰度是使用大速度梯度计算来估计的。 I20126 流出叶中推断的 SiO2 丰度为 (1-5) × 10-8，与冲击区域的预期增强相当。
We have imaged the outflow from the luminous young stellar object IRAS 20126+4104 (I20126) with the Submillimeter Array in CO (3-2), HCN (4-3), and SiO (5-4) at 1''-2'' resolutions within a radius of ~20'' from the central driving source. Our observations reveal at least three different components of the outflowing gas: (1) A compact (~4000 AU) bipolar outflow toward the central young stellar object. With a dynamical timescale of ~120 yr, this component represents a very new jet/outflow activity in I20126. (2) A collimated outflow with an extent of ~0.2 pc previously detected in SiO (2-1). Both morphology and kinematics favor this component being a jet-driven bow shock system. (3) An S-shaped CO outflow with an extent of ~0.4 pc. This component records the precession history very well. Its kinematic feature, where the velocity increases with distance from the YSO, indicates, independently of other evidence, that the outflow axis is moving toward the plane of the sky. The three outflow components record the history of the primary jet precession over scales ranging from a few hundred AU to approximately 0.4 pc. Our results indicate that CO (3-2) emission is a good tracer to probe the primary jet. The gas densities and SiO relative abundances in I20126 shocks are estimated using the large velocity gradient calculations. The inferred SiO abundances of (1-5) × 10-8 in I20126 outflow lobes are comparable to the expected enhancement at shocked regions.