Dense Cores of Dark Clouds. XII. 13CO and C18O in Lupus, Corona Australis, Vela, and Scorpius
Dense Cores of Dark Clouds. XII. 13CO and C18O in Lupus, Corona Australis, Vela, and Scorpius
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乌云的密集核心。
DOI：
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发表时间：
2000
期刊：
影响因子：
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通讯作者：
G. Fuller
中科院分区：
文献类型：
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作者：
J. W. Vilas;P. Myers;G. Fuller
在13CO和C18O （J = 1-0）的转变中，观测到狼座、南冕、牛座、船帆座和天蝎座的黑云有110多次密集凝聚。蛇夫座、金牛座和仙王座等恒星形成活跃的黑云凝聚体的C18O和H2柱平均密度分别为1.8 × 1015和1.1 × 1022 cm-2。如果我们取缩聚体的平均大小为0.2 pc，则缩聚体的平均H2体积密度必须≥2 × 104 cm-3，才能成为形成恒星的良好候选者。这四条狼疮细丝具有相似的径向速度和速度色散，这表明它们起源于同一个母云。在这些细丝中，狼疮1号在最近的恒星形成活动中是独一无二的，尽管在其他细丝中观察到大量的金牛座T星。“狼疮1号”沿其主轴也显示出复杂的速度梯度。观测到的天蝎座方向凝聚体的径向速度分布与它们位于膨胀速度小于或等于18 km s-1的区域的假设很好地吻合。南冕云的速度梯度范围从一个极端的-0.5 km s-1 pc-1到另一个极端的0.1 km s-1 pc-1。
More than 110 dense condensations of the dark clouds in Lupus, Corona Australis, Norma, Vela, and Scorpius were observed in the 13CO and C18O (J = 1-0) transitions. The condensations of dark clouds with high star formation activity like the Ophiuchus, Taurus, and Cepheus have average C18O and H2 column densities of 1.8 × 1015 and 1.1 × 1022 cm-2. If we take the average size of the condensations to be 0.2 pc, a condensation must have average H2 volumetric densities ≥2 × 104 cm-3 in order to be a good candidate to form stars. The four Lupus filaments have similar radial velocities and velocity dispersions, suggesting that they originated from the same parental cloud. Among these filaments, Lupus 1 is unique in having recent star formation activity, despite the high number of T Tauri stars observed toward the others. Lupus 1 also shows a complex velocity gradient along its main axis. The distribution of radial velocities of the condensations observed toward Scorpius are in good agreement with the hypothesis that they are in a region with expansion velocity smaller than or equal to 18 km s-1. The Corona Australis cloud has velocity gradients ranging from -0.5 km s-1 pc-1 at one extreme to 0.1 km s-1 pc-1 at the other.