An unbiased search for the signatures of protostars in the ρ Ophiuchi molecular cloud , II. Millimetre continuum observations
An unbiased search for the signatures of protostars in the ρ Ophiuchi molecular cloud , II. Millimetre continuum observations
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DOI：
10.1051/0004-6361:20041331
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发表时间：
2005-11
影响因子：
6.5
通讯作者：
T. Stanke;Michael D. Smith;R. Gredel;T. Khanzadyan
中科院分区：
文献类型：
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作者：
T. Stanke;Michael D. Smith;R. Gredel;T. Khanzadyan
孕育和孕育年轻恒星的致密核心可以通过相关尘埃颗粒的连续辐射来探索。我们对蛇夫座ρ分子云中1.2毫米处的尘埃源进行了广泛的实地调查，以无偏的方式覆盖超过1平方度。我们检测到一些以前未知的来源，从扩展的核心紧凑，无星核心的信封周围的年轻恒星0类，I类和II类类型的对象。分析了核的质量分布、空间分布和势平衡。就内陆地区而言，调查结果与以往范围较窄的调查结果一致。核心质量函数类似于恒星的初始质量函数，核心质量函数向更高质量移动了两倍（对于选定的不透明度和温度）。此外，我们没有发现统计变化的核心质量函数之间的拥挤的内部区域和那些在更孤立的领域，除了最大的核心在扩展云的情况下。内部区域包含多个内核。这被解释为由于介质的平均压力较高，虽然强大的压力变化是显而易见的，在每个区域。核心显示出分层的空间分布，没有首选的分离尺度长度。然而，最近邻的频率分布显示出两个峰值，其中一个峰值位于5000 Au处，可能是核心碎裂的结果。岩心的长轴方向符合各向同性分布。相反，在所有的分离尺度上，核心对的相对取向优先在NW-SE方向。这些结果是一致的核心生产和演变在动荡的环境。最后，我们报告发现了一个新的，低质量的0类对象候选人和CO外流。
The dense cores which conceive and cradle young stars can be explored through continuum emission from associated dust grains. We have performed a wide field survey for dust sources at 1.2 millimetres in the ρ Ophiuchi molecular cloud, covering more than 1 square degree in an unbiased fashion. We detect a number of previously unknown sources, ranging from extended cores over compact, starless cores to envelopes surrounding young stellar objects of Class 0, Class I, and Class II type. We analyse the mass distribution, spatial distribution and the potential equilibrium of the cores. For the inner regions, the survey results are consistent with the findings of previous narrower surveys. The core mass function resembles the stellar initial mass function, with the core mass function shifted by a factor of two to higher masses (for the chosen opacity and temperature). In addition, we find no statistical variation in the core mass function between the crowded inner regions and those in more isolated fields except for the absence of the most massive cores in the extended cloud. The inner region contains compacter cores. This is interpreted as due to a medium of higher mean pressure although strong pressure variations are evident in each region. The cores display a hierarchical spatial distribution with no preferred separation scale length. However, the frequency distribution of nearest neighbours displays two peaks, one of which at 5000 AU can be the result of core fragmentation. The orientations of the major axes of cores are consistent with an isotropic distribution. In contrast, the relative orientations of core pairs are preferentially in the NW-SE direction on all separation scales. These results are consistent with core production and evolution in a turbulent environment. Finally, we report the discovery of a new, low-mass Class 0 object candidate and its CO outflow.