标题： 红外暗云的建模 显示英文标题

标题： The Modelling of InfraRed Dark Clouds

摘要： 本文展示了针对一个红外暗云（IRDC）的三个不同核心的450微米和850微米连续谱以及HCO+线观测的建模结果，该IRDC指向W51分子云。 在这毫米波段连续谱中，这些核心表现为明亮且孤立的发射特征。 其中一个核心与由中途空间实验卫星测量的8.3微米消光峰值重合。 详细辐射转移代码被用于限制这些核心的物理条件以回答关键问题：这些IRDC核心是否孕育着亮源？ 连续谱模型的结果，通过 $\chi^2$ 质量拟合参数表达，也受到IRAS没有100微米发射这一事实的约束。 对于毫米波发射峰，这表明在这些核心内部嵌入了相当于300倍太阳亮度的源。 对于消光峰，连续谱和HCO+线建模的结合表明存在一个加热源。 此外，线模型提供了介质不均匀性的限制。 所有三个核心的质量约为70至150个太阳质量，并具有相似的密度结构。 消光峰与其他两个核心的不同之处在于它包含了一个弱得多的加热源，而IRDC边缘的毫米波发射核心则因更高的内部不均匀性而不同于其他核心。 显示英文摘要

摘要： This paper presents results from modelling 450 micron and 850 micron continuum and HCO+ line observations of three distinct cores of an infrared dark cloud (IRDC) directed toward the W51 GMC. In the sub-mm continuum these cores appear as bright, isolated emission features. One of them coincides with the peak of 8.3 micron extinction as measured by the Midcourse Space Experiment satellite. Detailed radiative transfer codes are applied to constrain the cores' physical conditions to address the key question: Do these IRDC-cores harbour luminous sources? The results of the continuum model, expressed in the $\chi^2$ quality-of-fit parameter, are also constrained by the absence of 100 micron emission from IRAS. For the sub-mm emission peaks this shows that sources of 300 solar luminosities are embedded within the cores. For the extinction peak, the combination of continuum and HCO+ line modelling indicates that a heating source is present as well. Furthermore, the line model provides constraints on the clumpiness of the medium. All three cores have similar masses of about 70-150 solar masses and similar density structures. The extinction peak differs from the other two cores by hosting a much weaker heating source, and the sub-mm emission core at the edge of the IRDC deviates from the other cores by a higher internal clumpiness.