Ejection History of the IRAS 04166+2706 Molecular Jet. (arXiv:1902.06038v1 [astro-ph.SR])

<a href="http://arxiv.org/find/astro-ph/1/au:+Wang_L/0/1/0/all/0/1">Liang-Yao Wang</a> (1 and 2), <a href="http://arxiv.org/find/astro-ph/1/au:+Shang_H/0/1/0/all/0/1">Hsien Shang</a> (1 and 2), <a href="http://arxiv.org/find/astro-ph/1/au:+Chiang_T/0/1/0/all/0/1">Tzu-Yang Chiang</a> (1 and 2) ( (1) Academia Sinica, Theoretical Institute for Advanced Research in Astrophysics, (2) Academia Sinica, Institute of Astronomy and Astrophysics, Taipei, Taiwan )

The high-velocity molecular jet driven by Class 0 protostar IRAS 04166+2706

exhibits a unique saw-tooth velocity pattern. It consists of a series of

well-aligned symmetric knots with similar averaged speeds, whose speeds at

peaks of emission decreases roughly linearly away from the origin. Recent ALMA

observations of knots R6 and B6 reveal kinematic behavior with expansion

velocity increasing linearly from the axis to the edge. This pattern can be

formed by a spherically expanding wind with axial density concentration. In

this picture, the diverging velocity profile naturally possesses an increasing

expansion velocity away from the axis, resulting in a tooth-like feature on the

position-velocity diagram through projection. Such geometric picture predicts a

correspondence between the slopes of the teeth and the outflow inclination

angles, and the same inclination angle of 52$^circ$ of the IRAS 04166+2706 can

generally explain the whole pattern. Aided by numerical simulations in the

framework of unified wind model by Shang et al. (2006), the observed velocity

pattern can indeed be generated. A proper geometrical distribution of the jet

and wind material is essential to the reconstruction the ejection history of

the system.

The high-velocity molecular jet driven by Class 0 protostar IRAS 04166+2706

exhibits a unique saw-tooth velocity pattern. It consists of a series of

well-aligned symmetric knots with similar averaged speeds, whose speeds at

peaks of emission decreases roughly linearly away from the origin. Recent ALMA

observations of knots R6 and B6 reveal kinematic behavior with expansion

velocity increasing linearly from the axis to the edge. This pattern can be

formed by a spherically expanding wind with axial density concentration. In

this picture, the diverging velocity profile naturally possesses an increasing

expansion velocity away from the axis, resulting in a tooth-like feature on the

position-velocity diagram through projection. Such geometric picture predicts a

correspondence between the slopes of the teeth and the outflow inclination

angles, and the same inclination angle of 52$^circ$ of the IRAS 04166+2706 can

generally explain the whole pattern. Aided by numerical simulations in the

framework of unified wind model by Shang et al. (2006), the observed velocity

pattern can indeed be generated. A proper geometrical distribution of the jet

and wind material is essential to the reconstruction the ejection history of

the system.

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