A Corona Australis cloud filament seen in NIR scattered light - II. Comparison with sub-millimeter data
A Corona Australis cloud filament seen in NIR scattered light - II. Comparison with sub-millimeter data
复制标题
近红外散射光中看到的澳大利亚日冕云丝 - II。
DOI：
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发表时间：
2009
期刊：
影响因子：
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通讯作者：
S. Porceddu
中科院分区：
文献类型：
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作者：
M. Juvela;V. Pelkonen;S. Porceddu
上下文尘埃的发射和散射为星际云的研究提供了工具。要正确地分析这些观测结果，必须详细了解颗粒的性质。然而，尘埃的性质被怀疑从弥漫到密集的区域。这些变化可能会影响我们对大尺度观测的解释（例如，团簇质谱）下至单个核的结构。目标。我们研究了南冕分子云的北方部分，它由一个暗条和暗条内一个致密的亚毫米核组成。我们的目标是测量该区域内的尘埃温度和亚毫米发射率。我们还希望确认近红外（NIR）表面亮度可用于研究即使是非常密集的云的结构。方法.我们扩展了我们以前的近红外映射的灯丝。用Spitzer 160 μ m和APEX/Laboca 870 μm图估算了尘埃色温。基于背景恒星的红化，近红外表面亮度，和热亚毫米尘埃排放的柱密度进行了比较。利用三维灯丝模型研究了各向异性照明对近红外表面亮度的影响以及尘埃温度测量的可靠性。结果相对于视消光，870 μ mi sκ870处的估计发射率=（1.3 ± 0.4）× 10 −5 mag −1。这与在漫射介质中发现的值相似。亚毫米发射率的显著增加似乎被排除在外。尽管饱和，近红外表面亮度能够准确地查明，并优于背景恒星的颜色过度的测量，柱密度最大值的确切位置。近红外和远红外数据都表明，辐射场的强度在暗条南部较高。
Context. Dust emission and scattering provide tools for the study of interstellar clouds. Detailed knowledge of grain properties is essential for correct analysis of these observations. However, dust properties are suspected to change from diffuse to dense regions. The changes could affect our interpretation of observations from large scales (e.g., clump mass spectra) down to the structure of individual cores. Aims. We study a northern part of the Corona Australis molecular cloud that consists of a filament and a dense sub-millimetre core inside the filament. Our aim is to measure dust temperature and sub-mm emissivity within the region. We also look for confirmation that near-infrared (NIR) surface brightness can be used to study the structure of even very dense clouds. Methods. We extend our previous NIR mapping south of the filament. The dust colour temperatures are estimated using Spitzer 160 μ ma nd APEX/Laboca 870 μm maps. The column densities derived based on the reddening of background stars, NIR surface brightness, and thermal sub-mm dust emission are compared. A three dimensional toy model of the filament is used to study the effect of anisotropic illumination on near-infrared surface brightness and the reliability of dust temperature determination. Results. Relative to visual extinction, the estimated emissivity at 870 μ mi sκ870 = (1.3 ± 0.4) × 10 −5 mag −1 . This is similar to the values found in diffuse medium. A significant increase in the sub-millimetre emissivity seems to be excluded. In spite of saturation, NIR surface brightness was able to accurately pinpoint, and better than measurements of the colour excesses of background stars, the exact location of the column density maximum. Both near- and far-infrared data show that the intensity of the radiation field is higher south of the filament.