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arXiv 1801.09680astro-ph.GAastro-ph.SR
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猎户座B致密核的空间分布

On the spatial distributions of dense cores in Orion B

Richard J. Parker

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14 pages, 10 figures (including 1 appendix), accepted for publication in MNRAS
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摘要：

我们量化了猎户座B恒星形成区三个空间上不同的区域中致密核心的空间分布。对于L1622、NGC 2068/NGC 2071和NGC 2023/NGC 2024，我们使用$\mathcal{Q}$ -参数测量空间子结构的量，并发现所有三个区域都是空间子结构（$\mathcal{Q} < 0.8$）。我们使用$Λ_{\rm MSR}$对质量偏析量进行了量化，发现最大质量的核心在NGC 2068/NGC 2071（$Λ_{\rm MSR} \sim 2$）中存在轻度质量偏析，在NGC 2023/NGC 2024中存在非常大的质量偏析（四个最大质量的核心为$Λ_{\rm MSR} = 28^{+13}_{-10}$）。L1622中的大部分块状核并不位于相对高表面密度或更深的重力位，而NGC 2068/NGC 2071和NGC 2023/NGC 2024中的块状核则明显如此。鉴于猎户座B的低密度（10个核心pc $^{-2}$）和核心的空间子结构，质量分离不可能是动态的。我们的结果也不一致的模拟中，最大质量的恒星形成通过竞争吸积，而不是暗示，磁场可能是重要的影响气体和恒星的原始空间分布在恒星形成区域。

英文摘要：

We quantify the spatial distributions of dense cores in three spatially distinct areas of the Orion B star-forming region. For L1622, NGC2068/NGC2071 and NGC2023/NGC2024 we measure the amount of spatial substructure using the $\mathcal{Q}$-parameter and find all three regions to be spatially substructured ($\mathcal{Q} < 0.8$). We quantify the amount of mass segregation using $Λ_{\rm MSR}$ and find that the most massive cores are mildly mass segregated in NGC2068/NGC2071 ($Λ_{\rm MSR} \sim 2$), and very mass segregated in NGC2023/NGC2024 ($Λ_{\rm MSR} = 28^{+13}_{-10}$ for the four most massive cores). Whereas the most massive cores in L1622 are not in areas of relatively high surface density, or deeper gravitational potentials, the massive cores in NGC2068/NGC2071 and NGC2023/NGC2024 are significantly so. Given the low density (10 cores pc$^{-2}$) and spatial substructure of cores in Orion B, the mass segregation cannot be dynamical. Our results are also inconsistent with simulations in which the most massive stars form via competitive accretion, and instead hint that magnetic fields may be important in influencing the primordial spatial distributions of gas and stars in star-forming regions.

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