The Seven Most Massive Clumps in W43-Main as Seen by ALMA: Dynamical Equilibrium and Magnetic Fields
The Seven Most Massive Clumps in W43-Main as Seen by ALMA: Dynamical Equilibrium and Magnetic Fields
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DOI：
10.3847/1538-4357/ab378d
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发表时间：
2019-07
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通讯作者：
P. Cortés;C. Hull;J. Girart;C. Orquera-Rojas;Sridharan T. K.;Zhi-Yun Li;F. Louvet;J. Cortés;V. J. M. L. Gouellec;R. Crutcher;S. Lai
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作者：
P. Cortés;C. Hull;J. Girart;C. Orquera-Rojas;Sridharan T. K.;Zhi-Yun Li;F. Louvet;J. Cortés;V. J. M. L. Gouellec;R. Crutcher;S. Lai
在这里，我们提出了新的阿尔马观测偏振尘埃排放的六个最大的团块在W 43-主。簇MM 2、MM 3、MM 4、MM 6、MM 7和MM 8已被分解成两个群体的碎片丝。从这两个群体中，我们提取了81个核心（96个与MM 1核心），质量在0.9 M到425 M之间，质量灵敏度为0.08 M。MM 6、MM 7和MM 8团块表现出明显的破碎化，但偏振强度显得稀疏而紧凑。MM 2、MM 3和MM 4星群的碎片较少，但每个星团的辐射都是由一个原恒星核控制的。此外，极化强度更广泛，在这个群体中显着更强。从极化发射，我们推导出详细的磁场模式，我们用它来估计磁场强度的六个团块中的四个。平均场强估计值在500 μG到1.8 mG之间。此外，我们从单碟和数据中检测并模拟了向MM 2和MM 3的下落运动，导致了M yr−1和M yr−1的质量下落率。使用我们的估计，我们通过计算总维里参数αtotal来评估我们的核的动力学平衡。对于可靠的现场估计的核心，我们发现，71%似乎是重力约束，而其余的29%不是。我们的结论是，这些未束缚的核心，这也是质量较小，仍在吸积，尚未达到临界质量。这也意味着不同的演化时间尺度，这基本上表明，星星在高质量细丝中的形成是不均匀的。
Here we present new ALMA observations of polarized dust emission from six of the most massive clumps in W43-Main. The clumps MM2, MM3, MM4, MM6, MM7, and MM8, have been resolved into two populations of fragmented filaments. From these two populations we extracted 81 cores (96 with the MM1 cores) with masses between 0.9 M⊙ to 425 M⊙ and a mass sensitivity of 0.08 M⊙. The MM6, MM7, and MM8 clumps show significant fragmentation, but the polarized intensity appears to be sparse and compact. The MM2, MM3, and MM4 population shows less fragmentation, but with a single protostellar core dominating the emission at each clump. Also, the polarized intensity is more extended and significantly stronger in this population. From the polarized emission, we derived detailed magnetic field patterns throughout the filaments that we used to estimate field strengths for four out of the six clumps. The average field strength estimates were found to lie between 500 μG to 1.8 mG. Additionally, we detected and modeled infalling motions toward MM2 and MM3 from single-dish and data, resulting in mass infall rates of M⊙ yr−1 and M⊙ yr−1. Using our estimations, we evaluated the dynamical equilibrium of our cores by computing the total virial parameter αtotal. For the cores with reliable field estimates, we found that 71% appear to be gravitationally bound while the remaining 29% are not. We conclude that these unbound cores, which are also less massive, are still accreting and have not yet reached a critical mass. This also implies different evolutionary timescales, which essentially suggests that star formation in high-mass filaments is not uniform.