CO and shocked H_2 in the highly collimated outflow from VLA 1623
CO and shocked H_2 in the highly collimated outflow from VLA 1623
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VLA 1623 高度准直流出中的 CO 和冲击 H_2
DOI：
10.1093/mnras/277.1.193
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发表时间：
1995
影响因子：
4.8
通讯作者：
D. M. Walther
中科院分区：
文献类型：
--
作者：
W. Dent;H. Matthews;D. M. Walther
我们展示了一颗被认为是“0级”的年轻星星VLA 1623流出的大尺度12 CO和H2图像。冲击的H2排放量显然是第一次与此流量。大部分的H2在于紧凑的节，其中每个是下游的一个高峰在高速CO。总流出量来自CO数据为0.10 M，其中大部分位于扩展的蓝移东南流。该方向的流出长度≥ 15弧分（0.7 pc），开口角≤ 1°.6。它可以分为两个区域：第一个区域，在星星的0.07 pc范围内，呈圆锥形。超过该半径，低速CO具有边缘变亮的形态，在高速下具有较窄的中心峰状通道;这指示沿圆柱形空腔的壁沿着流动。我们认为流出腔的大部分膨胀发生在源的初始0.07 pc内;超过此，分子流被限制在恒定宽度为10.03 pc的圆柱体内。CO和H2结果的比较倾向于表明VLA 1623的西北侧可能包含两个独立的流。近红外连续图像显示VLA 1623源周围的致密云在背景星云的剪影中。没有证据表明垂直于流出方向的伸长，核心有一个尖锐的外半径为1.002秒差距，没有证据表明周围有一个低密度的吸积包层。拟合消光的径向分布表明高斯密度梯度，而不是浅幂律密度梯度。
We show large-scale12CO and H2images of the outflow from the proposed 'class 0' young star VLA1623. Shocked H2emission is clearly associated for the first time with this flow. Most of the H2 lies in compact knots, each of which is downstream from a peak in the high-velocity CO. The total outflow mass derived from the CO data is 0.10 M⊙, most of which lies in the extended blueshifted south-east flow. The outflow in this direction is ≥ 15 arcmin (0.7 pc) in length with an opening angle of ≤ 1°.6. It can be divided into two regions: the first, within 0.07 pc of the star, has a conical shape. Beyond this radius, the low-velocity CO has a limb-brightened morphology, with a narrower, centrally peaked lane at high velocities; this is indicative of flow along the walls of a cylindrical cavity. We suggest that most expansion of the outflow cavity occurs within the initial 0.07 pc of the source; beyond this, the molecular flow is confined to a cylinder of constant width ˜ 0.03 pc. Comparison of the CO and H2 results tends to suggest that the north-west side of VLA 1623 may contain two separate flows.The near-infrared continuum image shows the dense cloud around the VLA 1623 source in silhouette against a background nebula. There is no evidence of elongation perpendicular to the outflow direction, and the core has a sharp outer radius of ˜ 0.02 pc, with no evidence of a surrounding lower density accreting envelope. Fits to the radial distribution of extinction indicate a Gaussian rather than shallow powerlaw density gradient.