High-Resolution Observations of the Molecular Clouds in the NGC 1333 IRAS 4 Region
High-Resolution Observations of the Molecular Clouds in the NGC 1333 IRAS 4 Region
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DOI：
10.1086/320657
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发表时间：
2001-05
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影响因子：
--
通讯作者：
Minho Choi
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文献类型：
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作者：
Minho Choi
在NGC 1333 IRAS 4区，在几条分子谱线上和毫米波连续谱上观测到了分子外流和致密核，角分辨率约为4′′。流出特别好地由HCN管线追踪。IRAS 4A东北-西南外流由几个紧凑的节点组成，这些节点间隔规则，并具有交替的位置角。这种“摆动”可以由“旋进”喷流或驱动源的准周期性爆发产生。在前一种情况下，导致原恒星盘进动或“摆动”的双星间距应该小于IRAS 4A 1和4A 2之间的间距。HCN图显示IRAS 4A南部还有另一个外流和IRAS 4 BI驱动的紧凑双极外流，但在IRAS 4 BII附近没有发现外流活动。利用C18 O线测得IRAS 4A致密核的中心速度为VLSR = 6.7 km s-1。在这个中心速度下，朝向IRAS 4A的光学粗线并没有明显的蓝偏，并且双峰线轮廓在这个特定情况下可能不是坠落运动的特征。IRAS 4 BII的光谱指数比IRAS 4A/4 BI更陡，从3.4到2.7 mm，这表明IRAS 4 BII可能比它的同伴更进化。
The molecular outflows and the dense cores in the NGC 1333 IRAS 4 region were observed in several molecular lines and in the millimeter continuum with ~4′′ angular resolution. The outflows were particularly well traced by the HCN line. The IRAS 4A northeast-southwestern outflow consists of several compact knots which are spaced regularly and have alternating position angles. This "wiggle" could be produced either by a "precessing" jet or by quasi-periodic outbursts of the driving source. In the former case, the binary separation causing either the precession or the "wobbling" of the protostellar disk should be smaller than the separation between IRAS 4A1 and 4A2. The HCN map shows yet another outflow to the south of IRAS 4A and a compact bipolar outflow driven by IRAS 4BI, but no outflow activity was found near IRAS 4BII. The central velocity of the IRAS 4A dense core is determined to be VLSR = 6.7 km s-1 using the C18O line. With this central velocity, the optically thick lines toward IRAS 4A are not significantly blue-skewed, and the double-peaked line profile may not be a signature of infall motion in this particular case. IRAS 4BII has a steeper spectral index from 3.4 to 2.7 mm than IRAS 4A/4BI, suggesting that IRAS 4BII may be more evolved than its companions.