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赫歇尔古尔德带巡天观测到的猎户座B稠密核群的性质

Properties of the dense core population in Orion B as seen by the Herschel Gould Belt survey

V. Konyves, Ph. Andre, D. Arzoumanian, N. Schneider, A. Men'shchikov, S. Bontemps, B. Ladjelate, P. Didelon, S. Pezzuto, M. Benedettini, A. Bracco, J. Di France… 展开作者

V. Konyves, Ph. Andre, D. Arzoumanian, N. Schneider, A. Men'shchikov, S. Bontemps, B. Ladjelate, P. Didelon, S. Pezzuto, M. Benedettini, A. Bracco, J. Di Francesco, S. Goodwin, K. L. J. Rygl, Y. Shimajiri, L. Spinoglio, D. Ward-Thompson, G. J. White

备注：
In press in Astronomy and Astrophysics. arXiv admin note: text overlap with arXiv:1507.05926
发表信息：
A&A 635, A34 (2020)
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摘要：

我们提出了一个详细的研究猎户座B云（d~400 pc），成像与PACS/SPIRE相机在70-500 $μ$米的赫歇尔古尔德带调查（HGBS）。我们发布了新的高分辨率的尘埃柱密度和尘埃温度图。在NGC 2023/2024、NGC 2068/2071和L1622这三个次区域，共发现了1768个无星致密核，其中约28-45%是星前自引力核。另外还发现了76个原恒星致密核，它们的典型寿命为$t_{\rm pre}=1.7_{-0.6}^{+0.8}$ Myr。星前核心质量函数（CMF）在约0.5 $M_\odot$处达到峰值，与Salpeter斜率-1.35相比，在高质量端符合对数斜率为-1.27 $\pm$ 0.24的幂律。在这一区域，我们证实了在背景消光中星前核形成效率（CFE）在基准值A_V_bg~7 mag附近存在一个转变，类似于Herschel在其他云中观察到的趋势。这不是一个尖锐的阈值，而是在A_V_bg<5时具有非常低的星前CFE的区域与A_V_bg $\gtrsim$ 10时具有较高的大致恒定CFE的区域之间的平滑过渡。星前核的总质量仅占A_V_bg $\gtrsim$ 7 mag的致密分子云气体的~20%。约60-80%的星前核与暗条紧密相连，当考虑到更完整的暗条结构样品时，这一比例可增加到>90%。有趣的是，最近的核心邻居之间的中值分离对应于在附近的分子云中通常观察到的典型的内部细丝宽度~0.1 pc。作为背景云柱密度的函数观察到的CMF的分析表明，最大规模的星前核心在空间上隔离在最高的柱密度的地区，并建议，更高和更低质量的星前核心可能形成更密集的细丝。

英文摘要：

We present a detailed study of the Orion B clouds (d~400 pc), imaged with the PACS/SPIRE cameras at 70-500 $μ$m by the Herschel Gould Belt survey (HGBS). We release new high-res. maps of column density and dust temperature. In the filamentary sub-regions NGC2023/2024, NGC2068/2071, and L1622, 1768 starless dense cores were identified, ~28-45% of which are self-gravitating prestellar cores. A total of 76 protostellar dense cores were also found. The typical lifetime of the prestellar cores was found to be $t_{\rm pre}=1.7_{-0.6}^{+0.8}$ Myr. The prestellar core mass function (CMF) peaks at ~0.5 $M_\odot$ and is consistent with a power law with log slope -1.27$\pm$0.24 at the high-mass end, compared to the Salpeter slope of -1.35. In this region, we confirm the existence of a transition in prestellar core formation efficiency (CFE) around a fiducial value A_V_bg~7 mag in background visual extinction, similar to the trend observed with Herschel in other clouds. This is not a sharp threshold, but a smooth transition between a regime with very low prestellar CFE at A_V_bg<5 and a regime with higher, roughly constant CFE at A_V_bg$\gtrsim$10. The total mass in the form of prestellar cores represents only ~20% of the dense molecular cloud gas at A_V_bg$\gtrsim$7 mag. About 60-80% of the prestellar cores are closely associated with filaments, and this fraction increases up to >90% when a more complete sample of filamentary structures is considered. Interestingly, the median separation between nearest core neighbors corresponds to the typical inner filament width of ~0.1 pc commonly observed in nearby molecular clouds. Analysis of the CMF observed as a function of background cloud column density shows that the most massive prestellar cores are spatially segregated in the highest column density areas, and suggests that both higher- and lower-mass prestellar cores may form in denser filaments.

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