An Electronic Publication Dedicated to Early Stellar Evolution and Molecular Clouds from the Editor Massive Molecular Outflows
An Electronic Publication Dedicated to Early Stellar Evolution and Molecular Clouds from the Editor Massive Molecular Outflows
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通讯作者：
H. Beuther;P. Schilke;Sridharan T. K.;K. Menten;C. M. Wamsley;F. Wyrowski
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作者：
H. Beuther;P. Schilke;Sridharan T. K.;K. Menten;C. M. Wamsley;F. Wyrowski
供日后提交。一旦我建立了一个网站在这里，我将沟通新的URL为在线存档的恒星形成通讯。为了了解大质量外流在高质量恒星形成中的作用，我们在12 CO J = 2−1跃迁中绘制了26个高质量恒星形成区域的早期演化。在11个空间分辨率下，在其中的21个中发现了双极分子外流。其他五个来源表现出混乱的形态，但强大的线翼。双极结构的高检出率证明，在低质量源中常见的外流也是大质量恒星形成过程中普遍存在的现象。这些流是巨大的，非常巨大和充满活力的，数据表明比以前认为的更强的准直。流动的动力时标与相关岩心的自由落体时标很好地对应。与已知的低质量流的相关性相比，我们发现直到高质量状态的连续性表明所有质量和光度的类似流形成情景。在10 - 4 L范围内的吸积率估计约为10 - 4 M yr - 1，高于低质量恒星形成的要求，但与高质量恒星形成的情况一致。此外，我们发现外流质量与核心质量之间的紧密相关性超过许多数量级。这两个量之间的强相关性表明，吸积效率f acc =˙M acc /（M核心/t ff）与喷流质量损耗率与吸积率之比f r（喷流与核心质量之比f acc f r = M射流/M核心）的乘积对于所有核心质量来说基本是恒定的。这再次表明，在很大的质量范围内，流的形成过程是相似的。此外，我们估计f r和f acc的中位数分别约为0.2和0.01，这与当前的射流夹带模式一致。总而言之，对双极流出数据的分析有力地支持了大质量恒星形成的理论，这些理论通过放大来解释，但其他方面类似的物理过程——主要是吸积——与它们的低质量对应。
for future submissions. Once I have set up a web site here, I will communicate the new URL for the online archive of the Star Formation Newsletter. With the aim of understanding the role of massive outflows in high-mass star formation, we mapped in the 12 CO J = 2 − 1 transition 26 high-mass star-forming regions at very early stages of their evolution. At a spatial resolution of 11 bipolar molecular outflows were found in 21 of them. The other five sources show confusing morphology but strong line wings. This high detection rate of bipolar structure proves that outflows common in low-mass sources are also ubiquitous phenomena in the formation process of massive stars. The flows are large, very massive and energetic, and the data indicate stronger collimation than previously thought. The dynamical timescales of the flows correspond well to the free-fall timescales of the associated cores. Comparing with correlations known for low-mass flows, we find continuity up to the high-mass regime suggesting similar flow-formation scenarios for all masses and luminosities. Accretion rate estimates in the 10 4 L range are around 10 −4 M yr −1 , higher than required for low-mass star formation, but consistent with high-mass star formation scenarios. Additionally, we find a tight correlation between the outflow mass and the core mass over many orders of magnitude. The strong correlation between those two quantities implies that the product of the accretion efficiency f acc = ˙ M acc /(M core /t ff) and f r (the ratio between jet mass loss rate and accretion rate), which equals the ratio between jet and core mass (f acc f r = M jet /M core), is roughly constant for all core masses. This again indicates that the flow-formation processes are similar over a large range of masses. Additionally, we estimate median f r and f acc values of approximately 0.2 and 0.01, respectively, which is consistent with current jet-entrainment models. To summarize, the analysis of the bipolar outflow data strongly supports theories which explain massive star formation by scaled up, but otherwise similar physical processes – mainly accretion – to their low-mass counterparts.