Variability of the NGC 1333 IRAS 4A Outflow: Silicon Monoxide Observations
Variability of the NGC 1333 IRAS 4A Outflow: Silicon Monoxide Observations
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NGC 1333 IRAS 4A 流出量的变化：一氧化硅观测
DOI：
10.1086/432113
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发表时间：
2005
期刊：
影响因子：
--
通讯作者：
Minho Choi
中科院分区：
文献类型：
--
作者：
Minho Choi
在SiO v = 0 J = 1→0线上观测到NGC 1333 IRAS 4A区域，角分辨率约为2”。SiO图显示了由紧凑的发射峰组成的高度准直的流出物。这张地图至少显示了两个外流：主要的两极外流在东北-西南方向，而较短的一个向南。主流出在东北叶的中部有一个急转弯。在弯曲的北部存在一个密集的分子云核，这表明流出物可能由于喷流核碰撞而偏转。双极出口的不对称形态、偏转流良好的准直性和复杂的运动学、弯道附近分子气体的低速发射以及偏转流中SiO发射的增强也支持了这一解释。预计偏转角度约为34°，并且流出的动能的很大一部分可能已经通过碰撞过程转移到周围的云。由于主外流是高度准直的，因此可以确定驱动源。较长的主流出可能是由IRAS 4A2驱动的，IRAS 4A2是原双星系统的次级成员，而较短的南流出则是由A1驱动的。对于流出和吸积之间的这种反相关性，可能的解释包括A1中流出活动开始的延迟以及二元组分之间吸积速率的逆转。
The NGC 1333 IRAS 4A region was observed in the SiO v = 0 J = 1 → 0 line with an angular resolution of about 2''. The SiO map revealed highly collimated outflows consisting of compact emission peaks. The map shows at least two outflows: the main bipolar outflow in the northeast-southwest direction and a shorter one toward the south. The main outflow displays a sharp bend in the middle of the northeastern lobe. The existence of a dense molecular cloud core just north of the bend suggests that the outflow may have been deflected as a result of jet-core collision. This explanation is also supported by the asymmetric morphology of the bipolar outflow, the good collimation and complicated kinematics of the deflected flow, the low-velocity emission from the molecular gas near the bend, and the enhancement of SiO emission in the deflected flow. The projected deflection angle is about 34°, and a significant fraction of the kinetic energy of the outflow may have been transferred to the ambient cloud through the collision process. Since the main outflow is highly collimated, it was possible to identify the driving source. The longer main outflow is probably driven by IRAS 4A2, the secondary member of the protobinary system, and the shorter southern outflow by A1, the primary. Possible explanations for this anticorrelation between outflow and accretion include a delay of the onset of outflow activity in A1 and a reversal of accretion rates between binary components.