在$0\rlap.{"}2$分辨率上解析BN对象的结构和运动学
Resolving the Structure and Kinematics of the BN Object at $0\rlap.{"}2$ Resolution
摘要：
我们提出了敏感的7毫米观测的H53 $α$复合线和相邻的连续，朝向猎户座BN/KL区域。在连续体中，我们检测BN对象，射电源I（GMR I）和红外源n（猎户座-n）的无线电对应物。通过与相同角分辨率但频率较低的观测结果进行比较，讨论了这些源的谱指数和角大小。在H53 $α$行中，我们仅检测BN对象。这是第一次从这个源中探测到射电复合线。BN的LSR径向速度从H53 $α$线，$v_{LSR} = 20.1 \pm 2.1$ km s $^{-1}$，是一致的，从以前的研究中发现的近红外线。虽然连续发射预计有相当大的光学深度在7毫米，所观察到的H53 $α$线发射是一致的光学薄的性质，我们讨论了这种明显的差异可能的解释。有证据表明存在速度梯度，BN的NE部分相对于SW部分红移了$\sim 10$ km s $^{-1}$。这与Jiang等人的建议一致，即BN可能沿着该方向驱动电离流出。
英文摘要：
We present sensitive 7 mm observations of the H53$α$ recombination line and adjacent continuum, made toward the Orion BN/KL region. In the continuum we detect the BN object, the radio source I (GMR I) and the radio counterpart of the infrared source n (Orion-n). Comparing with observations made at similar angular resolutions but lower frequency, we discuss the spectral indices and angular sizes of these sources. In the H53$α$ line we only detect the BN object. This is the first time that radio recombination lines are detected from this source. The LSR radial velocity of BN from the H53$α$ line, $v_{LSR} = 20.1 \pm 2.1$ km s$^{-1}$, is consistent with that found from previous studies in near-infared lines. While the continuum emission is expected to have considerable optical depth at 7 mm, the observed H53$α$ line emission is consistent with an optically-thin nature and we discuss possible explanations for this apparent discrepancy. There is evidence of a velocity gradient, with the NE part of BN being redshifted by $\sim 10$ km s$^{-1}$ with respect to the SW part. This is consistent with the suggestion of Jiang et al. that BN may be driving an ionized outflow along that direction.
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