W3（OH）复合物的W3观测：W3（H $_2$ O）和W3（OH）的物理和化学区别
SMA Observations of W3(OH) Complex: Physical and Chemical Differentiation between W3(H$_2$O) and W3(OH)
摘要：
报道了用亚毫米波阵列（SMA）在270 GHz处对W3（OH）和W3（H $_2$ O）配合物分子谱线的观测结果。虽然先前的观测已经将W3（H $_2$ O）分解为两个或三个子组分，但是这两个源的物理和化学性质没有得到很好的约束。我们的SMA观测清楚地分辨了W3（OH）和W3（H $_2$ O）连续谱核心。利用线性拟合工具XCLASS，我们确定并模拟了该复合物中丰富的分子光谱，包括两个核心中的多个CH $_3$ CN和CH $_3$ OH跃迁。HDO、C $_2$ H $_5$ CN、O $^{13}$ CS以及HCN、CH $_3$ CN和CH $_3$ OCHO的振动激发谱线仅在W3（H $_2$ O）中检测到。我们计算两个核心的气体温度和柱密度。结果表明，W3（H $_{2}$ O）具有较高的气体温度，和较大的柱密度比W3（OH），如先前观察到的，这表明两个核心之间的物理和化学差异。我们比较了W3（H $_2$ O）与Sgr B2（N）热核、猎户座KL热核和猎户座致密岭的分子丰度，并讨论了特定物种的化学起源。在W3（H $_2$ O）中观察到一个东西向的速度梯度，其延伸与水脉泽和射电喷流追踪到的双极外流方向一致。在W3（OH）上还观察到南北向的速度梯度。然而，根据目前的观测，我们还不能确定W3（OH）中的速度梯度是由旋转、外流还是各子分量的径向速度差引起的。
英文摘要：
We report on the Submillimeter Array (SMA) observations of molecular lines at 270 GHz toward W3(OH) and W3(H$_2$O) complex. Although previous observations already resolved the W3(H$_2$O) into two or three sub-components, the physical and chemical properties of the two sources are not well constrained. Our SMA observations clearly resolved W3(OH) and W3(H$_2$O) continuum cores. Taking the advantage of the line fitting tool XCLASS, we identified and modeled a rich molecular spectrum in this complex, including multiple CH$_3$CN and CH$_3$OH transitions in both cores. HDO, C$_2$H$_5$CN, O$^{13}$CS, and vibrationally excited lines of HCN, CH$_3$CN, and CH$_3$OCHO were only detected in W3(H$_2$O). We calculate gas temperatures and column densities for both cores. The results show that W3(H$_{2}$O) has higher gas temperatures, and larger column densities than W3(OH) as previously observed, suggesting physical and chemical differences between the two cores. We compare the molecular abundances in W3(H$_2$O) to those in the Sgr B2(N) hot core, the Orion KL hot core and the Orion Compact Ridge, and discuss the chemical origin of specific species. An east-west velocity gradient is seen in W3(H$_2$O), and the extension is consistent with the bipolar outflow orientation traced by water masers and radio jets. A north-south velocity gradient across W3(OH) is also observed. However, with current observations we can not assure if the velocity gradients are caused by rotation, outflow or radial velocity differences of the sub-components in W3(OH).
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