The JCMT Gould Belt Survey: first results from the SCUBA-2 observations of the Ophiuchus molecular cloud and a virial analysis of its prestellar core population
The JCMT Gould Belt Survey: first results from the SCUBA-2 observations of the Ophiuchus molecular cloud and a virial analysis of its prestellar core population
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DOI：
10.1093/mnras/stv376
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发表时间：
2015-02
影响因子：
4.8
通讯作者：
K. Pattle;D. Ward-Thompson;J. Kirk;G. White;G. White;E. Drabek-Maunder;J. Buckle;S. Beaulieu-S.-Beaulie
中科院分区：
文献类型：
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作者：
K. Pattle;D. Ward-Thompson;J. Kirk;G. White;G. White;E. Drabek-Maunder;J. Buckle;S. Beaulieu-S.-Beaulie
在这篇文章中，我们介绍了作为詹姆斯·克莱克·麦克斯韦望远镜(JCMT)古尔德带探测(GBS)的一部分，利用Scuba-2仪器对蛇夫座分子云进行的第一次观测。我们演示了将这些数据与之前的HARP CO、Herschel和IRAM N2H+观测相结合的方法，以便准确地量化蛇夫座中Scuba-2源的性质。我们制作了一份Scuba-2发现的所有来源的目录。我们把它们分为原恒星和无恒星核心。我们列出了所有没有恒星的核心，并进行了全面的维里分析，包括外部压力。这是第一次将外部压力包括在这个细节级别中。我们发现我们的大多数核心要么被捆绑，要么被病毒化。引力能和外部压力的平均值是相似的数量级，但在不同的地区有一些不同。我们发现，在Oph A区的核心是引力约束的前星核，而在Oph C和E区的核心是压力受限的。我们确定N2H+是一个很好的前星核结合物质的示踪剂，尽管我们发现了一些证据表明N2H+在非常高的核心密度下冻结。我们发现，在C18O和N2H+追踪的气体之间，非热线宽显著减小，这表明在较高密度下湍流的消散。我们发现临界Bonnor-Ebert稳定性判据并不是我们核心有界性的一个很好的指标。我们探测了前棕矮星候选者OphB-11，发现了与以前的工作一致的通量密度和质量。我们讨论了核心性质的区域差异，并为我们之前的假设找到了进一步的支持，即从西南到东北跨云的全球演化梯度，表明整个区域顺序地形成了恒星。
In this paper, we present the first observations of the Ophiuchus molecular cloud performed as part of the James Clerk Maxwell Telescope (JCMT) Gould Belt Survey (GBS) with the SCUBA-2 instrument. We demonstrate methods for combining these data with previous HARP CO, Herschel, and IRAM N2H+ observations in order to accurately quantify the properties of the SCUBA-2 sources in Ophiuchus. We produce a catalogue of all of the sources found by SCUBA-2. We separate these into protostars and starless cores. We list all of the starless cores and perform a full virial analysis, including external pressure. This is the first time that external pressure has been included in this level of detail. We find that the majority of our cores are either bound or virialized. Gravitational energy and external pressure are on average of a similar order of magnitude, but with some variation from region to region. We find that cores in the Oph A region are gravitationally bound prestellar cores, while cores in the Oph C and E regions are pressure-confined. We determine that N2H+ is a good tracer of the bound material of prestellar cores, although we find some evidence for N2H+ freeze-out at the very highest core densities. We find that non-thermal linewidths decrease substantially between the gas traced by C18O and that traced by N2H+, indicating the dissipation of turbulence at higher densities. We find that the critical Bonnor–Ebert stability criterion is not a good indicator of the boundedness of our cores. We detect the pre-brown dwarf candidate Oph B-11 and find a flux density and mass consistent with previous work. We discuss regional variations in the nature of the cores and find further support for our previous hypothesis of a global evolutionary gradient across the cloud from south-west to north-east, indicating sequential star formation across the region.