Submillimeter Array Observations of L1551 IRS 5 in CS J = 7-6
Submillimeter Array Observations of L1551 IRS 5 in CS J = 7-6
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CS J = 7-6 中 L1551 IRS 5 的亚毫米波阵列观测
DOI：
10.1086/421939
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发表时间：
2004
期刊：
影响因子：
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通讯作者：
Ji Yang
中科院分区：
文献类型：
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作者：
S. Takakuwa;N. Ohashi;P. Ho;C. Qi;D. Wilner;Qizhou Zhang;T. Bourke;N. Hirano;Minho Choi;Ji Yang
我们用亚毫米波阵在CS J = 7-6和343 GHz连续辐射下对原双星L1551 IRS 5的星周包络进行了成像，分辨率约为3“。连续辐射显示出在双星周围垂直于相关射电喷流轴的拉长结构（~220 × 100 Au）。CS辐射延伸超过~400 Au，呈现近似圆形对称，并显示出从东南（蓝移）到西北（红移）的速度梯度。速度梯度的方向与在C_（18）O J = 1-0中观察到的不同。这可能是因为旋转在CS包络中比在C18 O包络中更占主导地位，在C18 O包络中既存在下落又存在旋转。CS辐射可分为两个速度分量：（1）围绕原恒星的盘状“高速”结构，距离系统速度±1.0-1.5 km s-1;（2）位于原恒星西南方向的“低速”结构，距离系统速度小于1.0 km s-1。高速分量跟踪温暖和稠密的气体与运动学一致的旋转周围的原恒星。低速分量可能来自于流出物中夹带的稠密气体。或者，该分量可以跟踪具有垂直结构的包层中的下落和旋转气体。
We have imaged the circumstellar envelope around the binary protostar L1551 IRS 5 in CS J = 7-6 and 343 GHz continuum emission at ~3'' resolution using the Submillimeter Array. The continuum emission shows an elongated structure (~220 × 100 AU) around the binary perpendicular to the axis of the associated radio jet. The CS emission extends over ~400 AU, appears approximately circularly symmetric, and shows a velocity gradient from southeast (blueshifted) to northwest (redshifted). The direction of the velocity gradient is different from that observed in C18O J = 1-0. This may be because rotation is more dominant in the CS envelope than the C18O envelope, in which both infall and rotation exist. The CS emission can be divided into two velocity components: (1) a "high"-velocity disklike structure surrounding the protostar ±1.0-1.5 km s-1 from the systemic velocity, and (2) a "low"-velocity structure located southwest of the protostar less than 1.0 km s-1 from the systemic velocity. The high-velocity component traces warm and dense gas with kinematics consistent with rotation around the protostar. The low-velocity component may arise from dense gas entrained in the outflow. Alternatively, this component may trace infalling and rotating gas in an envelope with a vertical structure.