在NIR散射光中看到的南冕云丝I.与背景恒星消光的比较
A Corona Australis cloud filament seen in NIR scattered light I. Comparison with extinction of background stars
摘要：
利用现有的近红外（NIR）仪器，可以绘制出大面积的星际云散射的近红外线。表面亮度携带视线尘埃柱密度的信息。因此，散射光可以提供一个重要的工具，研究质量分布在静止的星际云在高，甚至亚弧秒分辨率。我们希望证实光散射在所有近红外波段中占主导地位的表面亮度的假设。此外，我们想表明，散射光可以用于精确估计尘埃柱密度的云与Av在1- 15等范围内。我们获得了南冕分子云中静止暗条的近红外图像。观测提供了J、H和Ks波段的漫射表面亮度图。假设信号是由散射光引起的，我们将表面亮度数据转换为尘柱密度图。同样的观测结果为大量背景恒星提供了过度的颜色。这些数据被用来导出云的消光图。两个，很大程度上独立的示踪剂的云结构进行了比较。结果在低于Av= 15米的区域，漫射表面亮度和背景恒星都导致类似的柱密度估计。现有的差异可以解释为正常的观测误差和背景星提供的反射采样偏差的结果。没有迹象表明，热尘埃排放将有显着的贡献，即使在Ks带。结果表明，在Av= 15等以下，散射光确实提供了绘制云结构的可靠方法。与使用背景星相比，它实际上还可以提供高得多的空间分辨率。
英文摘要：
With current near-infrared (NIR) instruments the near-infrared light scattered from interstellar clouds can be mapped over large areas. The surface brightness carries information on the line-of-sight dust column density. Therefore, scattered light could provide an important tool to study mass distribution in quiescent interstellar clouds at a high, even sub-arcsecond resolution. We wish to confirm the assumption that light scattering dominates the surface brightness in all NIR bands. Furthermore, we want to show that scattered light can be used for an accurate estimation of dust column densities in clouds with Av in the range 1-15mag. We have obtained NIR images of a quiescent filament in the Corona Australis molecular cloud. The observations provide maps of diffuse surface brightness in J, H, and Ks bands. Using the assumption that signal is caused by scattered light we convert surface brightness data into a map of dust column density. The same observations provide colour excesses for a large number of background stars. These data are used to derive an extinction map of the cloud. The two, largely independent tracers of the cloud structure are compared. Results. In regions below Av=15m both diffuse surface brightness and background stars lead to similar column density estimates. The existing differences can be explained as a result of normal observational errors and bias in the sampling of extinctions provided by the background stars. There is no indication that thermal dust emission would have a significant contribution even in the Ks band. The results show that, below Av=15mag, scattered light does provide a reliable way to map cloud structure. Compared with the use of background stars it can also in practice provide a significantly higher spatial resolution.
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