Dense Cores with Multiple Protostars: The Velocity Fields of L1448 IRS 3, NGC 1333 IRAS 2, and NGC 1333 IRAS 4
Dense Cores with Multiple Protostars: The Velocity Fields of L1448 IRS 3, NGC 1333 IRAS 2, and NGC 1333 IRAS 4
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具有多个原恒星的致密核心：L1448 IRS 3、NGC 1333 IRAS 2 和 NGC 1333 IRAS 4 的速度场
DOI：
10.1086/507437
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发表时间：
2006
期刊：
影响因子：
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通讯作者：
W. Welch
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文献类型：
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作者：
N. Volgenau;L. Mundy;L. Looney;W. Welch
嵌入的核心L1448 IRS 3，NGC 1333 IRAS 2和NGC 1333 IRAS 4被映射为C18 O，H13 CO+和N2 H + J = 1 → 0跃迁的发射。这些地图是通过结合比马和FCRAO观测创建的，并被调整到~ 50“、10”、5“和3”的分辨率。更高分辨率的地图显示的发射结构是相当小的特征核心半径（~0.1 pc）在早期的单碟研究中确定的。我们集中我们的研究在运动学的信封材料跟踪的发射线。我们发现，虽然FCRAO数据显示相对平滑的速度梯度的核心，更高的分辨率看到的速度场是随机的，与中心速度变化的范围为1公里秒-1。通常，速度的分布以及场的复杂性随着分辨率而增加。为了分析发射线宽度的变化，我们采用了网格化的数据立方体，最初开发的湍流云模型的属性进行量化的方法。即使在最小的可测量尺度下，芯也表现出宽范围的线宽。在普遍的包络温度（T ≤ 20 K）下的纯热展宽不足以产生测量的线宽;最窄的线必须具有至少与热分量一样大的湍流分量，并且对于几乎所有的线，湍流分量做出主要贡献。我们的研究结果表明，湍流运动持续到至少2400 Au的次核心尺度。
The embedded cores L1448 IRS 3, NGC 1333 IRAS 2, and NGC 1333 IRAS 4 are mapped in emission from the C18O, H13CO+, and N2H+ J = 1 → 0 transitions. The maps are created by combining BIMA and FCRAO observations and are tuned to resolutions of ~50'', 10'', 5'', and 3''. The higher resolution maps reveal emission structures that are considerably smaller than the characteristic core radius (~0.1 pc) identified in earlier single-dish studies. We focus our study on the kinematics of the envelope material traced by the emission lines. We find that although the FCRAO data show relatively smooth velocity gradients across the cores, the velocity fields seen with higher resolution are more random, with central velocities varying over a range of ~1 km s-1. In general, the distribution of velocities, as well as the complexity of the fields, increases with resolution. To analyze variations in the widths of the emission lines, we employ a method of gridding the datacubes that was initially developed to quantify properties of turbulent cloud models. The cores exhibit a broad range of line widths even at the smallest measurable scales. Pure thermal broadening at the prevailing envelope temperatures (T ≈ 20 K) is insufficient to produce the measured line widths; the narrowest lines must have a turbulent component at least as great as the thermal component, and for nearly all lines, the turbulent component makes the dominant contribution. Our results suggest that turbulent motions persist down to subcore scales of at least 2400 AU.