Scientific Highlights with the SMA

Magnetic field structure in the Flattened Envelope and Jet in the young protostellar system HH 211

HH 211 is a young Class 0 protostellar system, with a flattened envelope, a possible rotating disk, and a collimated jet. We have mapped it with the Submillimeter Array in 341.6 GHz continuum and SiO J=8-7 at ~ 0.6" resolution. The continuum traces the thermal dust emission in the flattened envelope and the possible disk. Linear polarization is detected in the continuum in the flattened envelope. The field lines implied from the polarization have different orientations (some toroidal and some poloidal), but they are not incompatible with current gravitational collapse models, which predict different orientation depending on the region/distance. Also, we might have detected for the first time polarized SiO line emission in the jet due to the Goldreich-Kylafis effect. Observations at higher sensitivity are needed to determine the field morphology in the jet (Lee et al. 2014, ApJL).

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Continuum intensity, polarization intensity and vectors, field orientation, and model field morphology. In (a) and (b), the blue contours show the continuum intensity map. The cross marks the source position. The blue and red arrows show the approaching and receding sides of the mean jet axis, respectively. In (a), the gray-scale image shows the polarization intensity greater than 2 σ detection. Line segments show the polarization vectors for the detection with 2 to 3.5 σ. (orange for 2-2.5 σ, green for 2.5-3 σ, and red for 3-3.5 σ). Polarization degree is indicated by the length of the vector. In (b) Line segments show the magnetic field orientations, some toroidal and some poloidal. (c) shows the model density (white contours and color image) and field (red lines) morphology adopted from Kataoka eta al. 2012, with the field axis (black lines) aligned with the jet axis of HH 211.