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arXiv 1605.03065astro-ph.GAastro-ph.SR
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在不同Viewing Angles下的尘丝外观

Appearance of Dusty Filaments at Different Viewing Angles

R. -A. Chira, R. Siebenmorgen, Th. Henning, J. Kainulainen

摘要:

内容:在过去的几年里,有许多关于暗条在恒星形成区域中的普遍存在和结构的研究,以及它们在恒星形成过程中的作用。这些细丝通常被认为是横跨天空平面的细长纤维。但我们如何检测倾斜的细丝呢?目的:我们的目标是更多地了解是否,以及如何,总柱密度或粉尘温度变化的视线。这种变化将使观测者能够利用尘埃观测来识别和研究任何倾斜度的细丝,并获得更多关于银河平面内细丝分布和方向的见解。研究方法:作为第一步,我们进行简单的圆柱模型的数值计算,以评估灯丝的几何形状的平均通量密度的影响。在此之后,我们应用我们的三维Monte Carlo尘埃辐射转移代码上的两个模型的恒星形成区,并得出有效的总柱密度和尘埃温度在不同的视角地图。结果:我们只看到我们研究的所有圆柱体的平均通量密度的轻微变化。对于我们更复杂的模型,我们发现,有效的尘埃温度是不敏感的视角,而总柱密度的强烈影响,差异超过一个数量级。这种变化与视角无关,而是取决于物体的结构。结论:我们的结论是,在我们的分析中,没有一个单一的量可以唯一地跟踪基于尘埃观测的灯丝的倾斜度和三维结构。然而,在给定的有效尘埃温度下观察到总柱密度的广泛变化表明倾斜的细丝。

英文摘要:

Context: In the last years, there have been many studies on the omnipresence and structures of filaments in star-forming regions, as well as their role in the process of star formation. Those filaments are normally identified as elongated fibres across the plane of the sky. But how would we detect filaments that are inclined? Aims: We aim to learn more about whether, and how, total column density or dust temperature change with respect to the line of sight. Such variations would enable observers to use dust observations to identify and study filaments at any inclination and gain more insight on the distribution and orientations of filaments within the Galactic plane. Methods: As a first step, we perform numerical calculations on simple cylindrical models to evaluate the influence of filament geometry on the average flux density. After that, we apply our three-dimensional Monte Carlo dust radiative transfer code on two models of star-forming regions and derive maps of effective total column density and dust temperature at different viewing angles. Results: We see only slight changes of average flux density for all cylinders we study. For our more complex models, we find that the effective dust temperature is not sensitive to viewing angle, while the total column density is strongly influenced, with differences exceeding an order of magnitude. The variations are not injective with the viewing angle and depend on the structure of the object. Conclusions: We conclude that there is no single quantity in our analysis that can uniquely trace the inclination and three-dimensional structure of a filament based on dust observations alone. However, observing wide variations in total column density at a given effective dust temperature is indicative of inclined filaments.

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