Spatially associated clump populations in Rosette from CO and dust maps
Spatially associated clump populations in Rosette from CO and dust maps
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DOI：
10.1093/mnras/stx3267
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发表时间：
2017-12
影响因子：
4.8
通讯作者：
T. Veltchev;V. Ossenkopf-Okada;O. Stanchev;N. Schneider;S. Donkov;R. Klessen
中科院分区：
文献类型：
--
作者：
T. Veltchev;V. Ossenkopf-Okada;O. Stanchev;N. Schneider;S. Donkov;R. Klessen
来自不同示踪剂的团块的空间关联被证明是确定分子云物理性质的一个有价值的工具。它提供了对$X因子的可靠估计，用于跟踪仅在柱密度中看到的团块密度，并允许测量在尘埃排放中确定的团块的速度弥散。我们研究了利用GAUSSCLUMPS技术从恒星形成区Rosette的CO(1-0)、CO(1-0)线图和Herschel尘埃发射图中提取的簇群之间的空间关联，并分析了它们的物理性质。所有与另一个CO或尘埃相对应的CO团簇都被发现受到引力的束缚，并位于分子云的大质量恒星形成丝中。它们服从单一的质量-尺寸关系M_(Rmcl)与r_(Rm)cl^\r(表示平均密度不变)，而几乎不表现出速度-尺寸关系。我们将它们的种群解释为通过汇聚的水流压缩而形成的低密度结构，并且仍然没有在自重的影响下演化。其团簇质量函数的高质量部分符合幂函数NrmCl/Rmd，对数Mrmc1，ProtoMrmCl，并表现出接近Salpeter斜率的GAMMA\SIM-1.3$。另一方面，从尘埃发射图中提取的团块呈现出较浅的质量-尺寸关系，其质量-尺寸关系为$\Gamma=2.5$，质量函数具有非常陡峭的斜率$\Gamma\sim-2.3$，即使与CO团块有关。它们在PC的十分之几的尺度上跟踪相关CO团块的密度峰，在那里不应该期望单一的密度标度律。
Spatial association of clumps from different tracers turns out to be a valuable tool to determine the physical properties of molecular clouds. It provides a reliable estimate for the $X$-factors, serves to trace the density of clumps seen in column densities only and allows to measure the velocity dispersion of clumps identified in dust emission. We study the spatial association between clump populations, extracted by use of the GAUSSCLUMPS technique from $^{12}$CO (1-0), $^{13}$CO (1-0) line maps and Herschel dust-emission maps of the star-forming region Rosette, and analyse their physical properties. All CO clumps that overlap with another CO or dust counterpart are found to be gravitationally bound and located in the massive star-forming filaments of the molecular cloud. They obey a single mass-size relation $M_{\rm cl}\propto R_{\rm cl}^\gamma$ with $\gamma\simeq3$ (implying constant mean density) and display virtually no velocity-size relation. We interpret their population as low-density structures formed through compression by converging flows and still not evolved under the influence of self-gravity. The high-mass parts of their clump mass functions are fitted by a power law ${\rm d}N_{\rm cl}/{\rm d}\,\log M_{\rm cl}\propto M_{\rm cl}^{\Gamma}$ and display a nearly Salpeter slope $\Gamma\sim-1.3$. On the other hand, clumps extracted from the dust-emission map exhibit a shallower mass-size relation with $\gamma=2.5$ and mass functions with very steep slopes $\Gamma\sim-2.3$ even if associated with CO clumps. They trace density peaks of the associated CO clumps at scales of a few tenths of pc where no single density scaling law should be expected.