arXiv 1104.29502011-04-26astro-ph.SR

无星致密核的内部运动

Internal Motions in Starless Dense Cores

Chang Won Lee, Philip C. Myers

备注：: Accepted for publication in The Astrophysical Journal, 34 pages, and 14 figures
DOI：: 10.1088/0004-637X/734/1/60

摘要：

本文讨论了无星致密核内部运动的统计特性及其与核密度和演化的关系。从几十个无星核的单点和映射观测中分析了三种分子的四条谱线。蓝色的不对称轮廓占主导地位，表明向内运动在足够密集的无星核心中很普遍。这些蓝色的配置文件被发现是更丰富的，他们的不对称性是蓝色的，在核心位置与较强的$\rm N_2H^+$线发射或更高的列密度。根据分子谱线图中谱线的蓝移和红移，将33个无星核分为4类。在这些核心中，收缩运动占主导地位：19个被归类为收缩，3个为振荡，3个为膨胀，8个为静态。收缩核在整个核内都有向内的运动，这些运动在峰值密度区域附近占主导地位。具有最蓝不对称性的芯倾向于具有比其他芯更大的柱密度，并且发现具有峰值柱密度$> \rm 6\times 10^{21} cm^{-2}$的所有五个芯都在收缩。这表明，如果没有恒星的核心足够凝聚，它们可能会有收缩运动。我们对无星核的分类可能表明了一个核演化的序列，从这个意义上说，柱密度从静态核到收缩核增加：最早阶段的静态核，下一阶段的膨胀和/或振荡核，以及最后阶段的收缩核。

英文摘要：

This paper discusses the statistics of internal motions in starless dense cores and the relation of these motions to core density and evolution. Four spectral lines from three molecular species are analyzed from single-pointing and mapped observations of several tens of starless cores. Blue asymmetric profiles are dominant, indicating that inward motions are prevalent in sufficiently dense starless cores. These blue profiles are found to be more abundant, and their asymmetry is bluer, at core positions with stronger $\rm N_2H^+$ line emission or higher column density. Thirty three starless cores are classified into four types according to the blue and red shifts of the lines in their molecular line maps. Among these cores, contracting motions dominate: 19 are classified as contracting, 3 as oscillating, 3 as expanding, and 8 as static. Contracting cores have inward motions all over the core with predominance of those motions near the region of peak density. Cores with the bluest asymmetry tend to have greater column density than other cores and all five cores with peak column density $> \rm 6\times 10^{21} cm^{-2}$ are found to be contracting. This suggests that starless cores are likely to have contracting motions if they are sufficiently condensed. Our classification of the starless cores may indicate a sequence of core evolution in the sense that column density increases from static to contracting cores: the static cores in the earliest stage, the expanding and/or the oscillating cores in the next, and the contracting cores in the latest stage.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

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