arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1508.04425astro-ph.GAastro-ph.SR
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大质量恒星形成区W42的物理环境

Physical environment of massive star-forming region W42

L. K. Dewangan, A. Luna, D. K. Ojha, B. G. Anandarao, K. K. Mallick, Y. D. Mayya

摘要:

我们提出了一个多波长的观测分析,从各种数据集和银河平面调查研究在W 42复杂的恒星形成过程。由于O 5-O 6型恒星在高度不均匀的介质中的电离反馈,W 42复合体的双极外观是明显的。VLT/NACO自适应光学K和L'图像(分辨率约为0”.2-0”.1)将该电离源分解为低于约5000 AU尺度的多个点状源。W 42分子云的位置角~15 °与H波段星光平均偏振角一致,而H波段星光平均偏振角与银河系磁场接近,表明银河系磁场对W 42分子云的演化有影响。Herschel亚毫米数据分析揭示了沿双极星云腰轴分布的三个团块,其峰值柱密度约为3-5 x10^{22} cm^{-2},对应于AV ~32-53.5 mag. Herschel温度图描绘了W 42的温度梯度,揭示了20 K、25 K和30-36 K的区域。赫歇尔图显示了嵌入的暗条(长度约1-3 pc),它们似乎径向指向与O 5-O 6星相关的密度更高的团块,形成了一个中心暗条系统。在复合体中识别出512个候选年轻恒星天体(YSO),其中约40%存在于主要分布在分子云中的星团中,包括赫歇尔细丝。我们的数据表明,包括大质量恒星在内的YSO星团位于丝状体的交界处,类似于玫瑰分子云中所看到的。

英文摘要:

We present an analysis of multi-wavelength observations from various datasets and Galactic plane surveys to study the star formation process in the W42 complex. A bipolar appearance of W42 complex is evident due to the ionizing feedback from the O5-O6 type star in a medium that is highly inhomogeneous. The VLT/NACO adaptive-optics K and L' images (resolutions ~0".2-0".1) resolved this ionizing source into multiple point-like sources below ~5000 AU scale. The position angle ~15 deg of W42 molecular cloud is consistent with the H-band starlight mean polarization angle which in turn is close to the Galactic magnetic field, suggesting the influence of Galactic field on the evolution of the W42 molecular cloud. Herschel sub-millimeter data analysis reveals three clumps located along the waist axis of the bipolar nebula, with the peak column densities of ~3-5 x10^{22} cm^{-2} corresponding to visual extinctions of AV ~32-53.5 mag. The Herschel temperature map traces a temperature gradient in W42, revealing regions of 20 K, 25 K, and 30-36 K. Herschel maps reveal embedded filaments (length ~1-3 pc) which appear to be radially pointed to the denser clump associated with the O5-O6 star, forming a hub-filament system. 512 candidate young stellar objects (YSOs) are identified in the complex, ~40% of which are present in clusters distributed mainly within the molecular cloud including the Herschel filaments. Our datasets suggest that the YSO clusters including the massive stars are located at the junction of the filaments, similar to those seen in Rosette Molecular Cloud.

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