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Shaped B field lines in the massive star-forming region Orion BN/KL

Image Credit: Tang et al.

B field map (red-segments) inferred from the polarization of thermal dust emission at 870 micron (black contours) is shown. The asterisk, star, cross and plus mark the position of BN, source I, SMA1 and source n, respectively. The square marks the BN-I center, where the trajectories of BN and I are overlapped ~ 500 yr ago. The BN-I center is also the origin of the 0.3 pc explosive molecular outflows.

With the Submillimeter Array, the B field geometry is resolved up to 1" (2mp; 480 AU) toward the densest region of the closest massive star forming region Orion BN/KL. We ﬁnd an azimuthally symmetric structure in the overall B ﬁeld morphology, with the ﬁeld directions pointing toward 2.5" west to the center of the explosive outﬂows. We also find a preferred symmetry plane at a position angle of 36 degree, which is perpendicular to the mean B ﬁeld direction (120 degree) of the 0.5 pc dust ridge. The B field lines is evidently shaped either by the outflows, by the contraction or by the differential rotation of an magnetized pseudo-disk. (Tang et al. 2010, ApJ, 717, 1262)