A distance-limited sample of massive molecular outflows
A distance-limited sample of massive molecular outflows
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DOI：
10.1093/mnras/stv1635
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发表时间：
2015-09
影响因子：
4.8
通讯作者：
L. Maud;T. Moore;S. Lumsden;J. Mottram;J. Urquhart;M. Hoare
中科院分区：
文献类型：
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作者：
L. Maud;T. Moore;S. Lumsden;J. Mottram;J. Urquhart;M. Hoare
我们用詹姆斯·克拉克麦克斯韦望远镜观测了99个中红外明亮的、大质量的年轻恒星天体和致密的H ii区，这些天体是从12 CO和13 CO的J = 3−2跃迁的红MSX源巡天中绘制的。其中89个目标距离太阳6千秒差距以内，涵盖了具有代表性的光度和核心质量范围。这些构成了与大质量星星形成相关的双极分子流出的相对公正的样本。其中，59、17和13个来源国（66%、19%和15%）分别被发现有流出、有一些流出证据和没有流出证据。利用空间可变的动态时间尺度计算了高速分子流的时变参数。流出参数和源光度之间的正则相关恢复，并与低质量源的尺度。对于同时代的星星的形成，我们发现的缩放是一致的，所有的原恒星在一个嵌入式集群提供外流的力量，与大质量的恒星高达30 M的外流。从表面上看，这些结果支持了与吸积相关的外流产生机制的放大版本模型，该机制与低质量物体中的圆盘和喷流有关，其核心的时间平均吸积速率为10 - 3 M·yr-1。然而，我们也提出了一个替代模型，其中的分子外流动力学是由夹带质量和无关的加速机制的细节。我们发现没有证据表明，外流的湍流动能的周围致密的核心作出重大贡献。
We have observed 99 mid-infrared-bright, massive young stellar objects and compact H ii regions drawn from the Red MSX source survey in the J = 3−2 transition of 12CO and 13CO, using the James Clerk Maxwell Telescope. 89 targets are within 6 kpc of the Sun, covering a representative range of luminosities and core masses. These constitute a relatively unbiased sample of bipolar molecular outflows associated with massive star formation. Of these, 59, 17 and 13 sources (66, 19 and 15 per cent) are found to have outflows, show some evidence of outflow, and have no evidence of outflow, respectively. The time-dependent parameters of the high-velocity molecular flows are calculated using a spatially variable dynamic time-scale. The canonical correlations between the outflow parameters and source luminosity are recovered and shown to scale with those of low-mass sources. For coeval star formation, we find the scaling is consistent with all the protostars in an embedded cluster providing the outflow force, with massive stars up to ∼30 M⊙ generating outflows. Taken at face value, the results support the model of a scaled-up version of the accretion-related outflow-generation mechanism associated with discs and jets in low-mass objects with time-averaged accretion rates of ∼10−3 M⊙ yr−1 on to the cores. However, we also suggest an alternative model, in which the molecular outflow dynamics are dominated by the entrained mass and are unrelated to the details of the acceleration mechanism. We find no evidence that outflows contribute significantly to the turbulent kinetic energy of the surrounding dense cores.