Dynamical Collapse in W51 Massive Cores: NH3 Observations
Dynamical Collapse in W51 Massive Cores: NH3 Observations
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DOI：
10.1086/304667
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发表时间：
1997-10
期刊：
影响因子：
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通讯作者：
Qizhou Zhang;P. Ho
中科院分区：
文献类型：
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作者：
Qizhou Zhang;P. Ho
本文报道了W_（51）H_Ⅱ区配合物在NH_3（J，K）=（1，1），（2，2），（3，3）反转跃迁中的高角分辨（0.“2- 1”，~1600-8000 Au）研究.这个区域以前已经被引力坍缩的光谱特征所识别。在其中一个坍缩核心W51 e2中，我们探测到了距离星星约1“（0.04 pc）尺度下约3.5 km s-1的径向坍缩。地核的向内运动几乎是恒定的。在106 cm-3尺度上存在约4 km s-1的速度梯度。NH3的旋转温度在整个塌缩区域保持大致恒定。质量密度在下落区向内增加，并与半径成比例r-2。在不同的空间尺度上，这种密度分布和下落区的总质量与等速自由福尔斯下落相一致。
We present high angular resolution (0.″2-1'', ~1600-8000 AU) studies of the W51 H II region complex in the NH3 (J, K) = (1, 1), (2, 2), and (3, 3) inversion transitions. This region has been identified previously with spectroscopic signatures of gravitational collapse. In one of the infalling cores, W51e2, we detect radial infall of ~3.5 km s-1 at scales of ~1'' (0.04 pc) from the star. The inward motion in the core is nearly constant. A velocity gradient of ~4 km s-1 exists at scales 106 cm-3). The NH3 rotational temperature remains roughly constant throughout the collapsing region. The mass densities in the infall region increase inward and scale with radius as r-2. This density distribution and the total mass in the infall zones are consistent with free falls of constant speed at different spatial scales.