论文标题
猎户座源I的磁场结构I
Magnetic Field Structure of Orion Source I
论文作者
论文摘要
我们观察到SIO旋转从猎户座源I（SRCI）的极化，以探测该高质量质体的双极外流中的磁场。使用非常大的阵列（VLA）和Atacama大型毫米/亚毫米阵列（ALMA），分别使用$ \ sim $ 20 AU分辨率绘制了43 GHz $ j $ = 1-0和86 GHz $ j $ = 2-1线。地面振动状态下的$^{28} $ SIO过渡是热和maser发射的混合物。 $ J $ = 1-0和$ j $ = 2-1过渡中的极化位置角度的比较使我们能够对$ 10^{4} $ RADIANS M $^{ - 2} $的Faraday轮换设置上限，这将扭动$ J $ = 2-1位置角度通常比10度降低。流出裂片中光滑的，系统的极化结构表明，几百个AU的尺度上有一个有序的磁场。两极分化的均匀性表明$ \ sim $ 30毫升高巨人的野外强度。它足够强，可以塑造双极流出，并可能导致流出底部的气体旋转。在$^{28} $ sio $ v $ = 0中，高度高的分数线性极化为80-90％，需要各向异性泵送。我们在$ v $ = 0 $ j $ = 1-0的峰值中测量了60％的圆形极化。各向异性谐振散射（ARS）可能是该圆极化的原因。我们还介绍了$^{29} $ sio $ v $ = 0 $ j $ = 2-1 maser和其他几个SIO过渡的地图，该地图在较高的振动级别和同位素上。
We observed polarization of the SiO rotational transitions from Orion Source I (SrcI) to probe the magnetic field in bipolar outflows from this high mass protostar. Both 43 GHz $J$=1-0 and 86 GHz $J$=2-1 lines were mapped with $\sim$20 AU resolution, using the Very Large Array (VLA) and Atacama Large Millimeter/Submillimeter Array (ALMA), respectively. The $^{28}$SiO transitions in the ground vibrational state are a mixture of thermal and maser emission. Comparison of the polarization position angles in the $J$=1-0 and $J$=2-1 transitions allows us to set an upper limit on possible Faraday rotation of $10^{4}$ radians m$^{-2}$, which would twist the $J$=2-1 position angles typically by less than 10 degrees. The smooth, systematic polarization structure in the outflow lobes suggests a well ordered magnetic field on scales of a few hundred AU. The uniformity of the polarization suggests a field strength of $\sim$30 milli-Gauss. It is strong enough to shape the bipolar outflow and possibly lead to sub-Keplerian rotation of gas at the base of the outflow. The strikingly high fractional linear polarizations of 80-90% in the $^{28}$SiO $v$=0 masers require anisotropic pumping. We measured circular polarizations of 60% toward the strongest maser feature in the $v$=0 $J$=1-0 peak. Anisotropic resonant scattering (ARS) is likely to be responsible for this circular polarization. We also present maps of the $^{29}$SiO $v$=0 $J$=2-1 maser and several other SiO transitions at higher vibrational levels and isotopologues.
