[论文解读] Interaction of the central jet with the surrounding gas in the protostellar outflow from IRAS 04166+2706

M. Tafalla, D. Johnstone+4 more|arXiv (Cornell University)|Jan 8, 2026

Astrophysics and Star Formation Studies被引用 0

一句话总结

该论文利用 ALMA 将 IRAS 04166+2706 的喷流映射，显示极高速度(EHV)气体与较慢喷出物之间存在物理联系，并提出一个简单的弹道模型，其中横向喷射将动量传递给周围的剪切流。

ABSTRACT

$Context.$ The outflow from the Class 0 protostar IRAS 04166+2706 (hereafter IRAS 04166) contains a remarkably symmetric jet-like component of extremely high-velocity (EHV) gas. $Aims.$ We studied the IRAS 04166 outflow and investigated the relation between its EHV component and the slower outflow gas. $Methods.$ We mosaicked the CO(2--1) emission from the IRAS 04166 outflow using the 12m and the Compact Arrays of ALMA. We also developed a ballistic toy model of the gas ejected laterally from a jet to interpret the data. $Results.$ In agreement with previous observations, the ALMA data show that the slow outflow component is distributed in two opposed conical lobes and has a shear-flow pattern with velocity increasing toward the axis. The EHV gas consists of a series of arc-like condensations that span the full width of the conical lobes and merge with their walls, suggesting that the fast and slow outflow components are physically connected. In addition, position--velocity diagrams along the outflow axis show finger-like extensions that connect the EHV emission with the origin of the diagram, as if part of the EHV gas had been decelerated by its interaction with the low-velocity outflow. A ballistic model can reproduce these finger-like extensions assuming that the EHV gas consists of jet material that has been ejected laterally over a short period of time and has transferred part of its momentum to the surrounding shear flow. $Conclusions.$ The EHV gas in the IRAS 04166 outflow seems to play a role in the acceleration of the slower gas component. The presence of similar finger-like extensions in the position-velocity diagrams of other outflows suggests that this process may be occurring in other systems, even if the EHV component is not seen because it has an atomic composition.

研究动机与目标

• 研究 IRAS 04166+2706 中 EHV 分量与较慢 SHV 喷出物之间的关系。
• 表征 EHV 气体的空间与动力结构及其与 SHV 壁的联系。
• 评估 EHV 气体通过相互作用是否对较慢喷出物的加速产生影响。
• 开发一个简化模型以解释喷射物横向喷射与周围介质相互作用的机理。

提出的方法

• 用 ALMA 12m 和 ACA 拼接在喷出物全长上成像 CO(2–1) 发射，以回收 EHV 和 SHV 区域。
• 观测额外的谱线（SiO(5–4)、13CO(2–1)、SO(6,5–5,4)），具有相似的速度分辨率，尽管灵敏度有限。
• 沿喷出轴构建位置–速度图以识别锯齿图样和指状特征。
• 提出一个简单的弹道模型，假设喷射物在横向射出时守恒动量并与周围的剪切流相互作用，以解释 PV 特征。

Figure 1: Maps of the CO(2–1) intensity integrated over the EHV and SHV velocity regimes. The velocity ranges of integration are given inside square brackets and are measured with respect to a cloud LSR velocity of 6.7 km s -1 . The map coordinates are offsets measured with respect to the position o

实验结果

研究问题

• RQ1 IRAS 04166+2706 中 EHV 分量的空间与速度结构是什么，它与 SHV 喷出之间有何关系？
• RQ2 EHV 凝聚体是否与 SHV 壁合并，指示物理相互作用和动量传递？
• RQ3 一个简单的横向喷射弹道模型是否能再现观测到的指状 PV 特征和锯齿状速度模式？
• RQ4 EHV 分量是否有助于加速较慢的 SHV 气体？
• RQ5 其他喷出物是否也出现类似的指状 PV 特征，暗示喷射–环境相互作用机制的普遍性？

主要发现

• SHV 气体形成两个对向的圆锥形喷口，具有肋状明亮壳层，而 EHV 气体表现为一系列弧状凝聚体，横跨 SHV 喷口的全宽并与其壁合并。
• PV 图显示 EHV 分量中的锯齿模式和指状特征，将 EHV 峰值连回到起点，暗示与较慢喷出物的相互作用。
• 一个弹道 toy 模型，在内部冲击期间喷射物横向射出，能够再现 PV 空间中的指状延伸，与对 SHV 流动的动量传递一致。
• EHV 气体似乎在加速较慢的 SHV 分量方面发挥作用，因为连续的 EHV 弧状与其与 SHV 壁的合并所指示。
• 在其他喷出物中看到的类似指状 PV 延伸，表明通过横向喷射的喷射物与环境相互作用可能是普遍过程，即使 EHV 分量并不明显可见。

Figure 2: Maps of the combined blueshifted and redshifted EHV emission of CO(2–1), SiO(5–4), and SO(6,5–5,4) toward the inner $25^{\prime\prime}\times 25^{\prime\prime}$ of the IRAS 04166 outflow. For CO(2–1) and SiO(5–4), the first contour and contour interval are 9 K km s -1 , while for the weaker