Sunday, May 19, 2013

1305.3681 (Hauyu Baobab Liu et al.)

Gas kinematics and the Dragged Magnetic Field in the High-mass Molecular Outflow Source G192.16$-$3.84: An SMA View    [PDF]

Hauyu Baobab Liu, Keping Qiu, Qizhou Zhang, Josep M. Girart, Paul T. P. Ho
We report the Submillimeter Array (SMA) observations of the polarized 0.88\,mm thermal dust emission and various molecular line transitions toward the early B-type ($L_{*}\sim2\times10^{3}L_{\odot}$) star-forming region G192.16$-$3.84 (IRAS 05553+1631). The peak of the continuum Stokes-I emission coincides with a hot rotating disk/envelope (SO$_{2}$ rotational temperature T$_{rot}^{SO_{2}}$$\sim84^{+18}_{-13}$\,K), with a north-south velocity gradient. Joint analysis of the rotation curve traced by HCO$^{+}$ 4-3 and SO$_{2}$ 19$_{1,19}-18_{0,18}$ suggests that the dense molecular gas is undergoing a spinning-up rotation, marginally bound by the gravitational force of \textbf{an} enclosed mass $M_{*+gas+dust}\sim$11.2-25.2\,$M_{\odot}$. Perpendicular to the rotational plane a $\gtrsim100/\cos(i)$\,km\,s$^{-1}$ ($i\sim63^{\circ}$) high velocity molecular jet, and the $\sim$15-20\,km\,s$^{-1}$ expanding biconical cavity were revealed in the CO 3-2 emission. The polarization percentage of the 0.88\,mm continuum emission decreases toward the central rotating disk/envelope. The polarization angle in the inner $\sim2"$ (0.015\,pc) disk/envelope is perpendicular to the plane of the rotation. The magnetic field lines, which are predominantly in the toroidal direction along the disk plane, are likely to be dragged by the gravitationally accelerated rotation.
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