论文标题
在赫歇尔丝的典型宽度上
On the typical width of Herschel filaments
论文作者
论文摘要
Herschel的研究表明，附近（D <500 PC）分子丝具有典型的半功率宽度〜0.1pc，但是这一发现受到质疑，理由是测得的宽度倾向于随距离而增加。在这里，我们重新审视了测得的灯丝宽度对距离或等效空间分辨率的依赖性，以确定附近的分子丝是否具有特征性的半功率宽度，还是这是否是Herschel数据有限分辨率的伪像。我们通过几次降解Herschel数据的分辨率并从所得的柱密度曲线中重新估计灯丝宽度，对金牛座的B211/213细丝进行收敛测试。我们还比较了金牛座细丝和其他细丝的宽度与Herschel Gould Belt调查的其他细丝与具有各种类型的简单，理想化的柱密度曲线的合成细丝发现的宽度。我们发现，随着空间分辨率恶化和/或细丝的距离增加，测得的灯丝宽度确实会略有增加。但是，这种趋势与简单光束卷积的期望完全一致，对于像垂体一样密度曲线且具有固有的半功率直径约为0.08-0.1 PC和对数斜率1.5 <p <2.5的固有的半功能直径约为底线，在许多情况下，在包括金牛座的丝状包括的许多情况下。由于存在背景噪声波动，因此从望远镜束上测得的宽度的反卷积迅速变得不准确。我们得出的结论是，在附近的云中用赫歇尔测量的典型的半功率宽度〜0.1 PC最有可能反映在冷星际介质的丝状结构中存在真正的常见尺度，至少至少在太阳邻居中。我们建议这种常见量表可能对应于分子云中磁化的湍流相关长度。
Herschel studies suggest that nearby (d < 500 pc) molecular filaments have a typical half-power width ~0.1pc, but this finding has been questioned on the ground that the measured widths tend to increase with distance. Here we revisit the dependence of measured filament widths on distance or equivalently spatial resolution, in an effort to determine whether nearby molecular filaments have a characteristic half-power width or whether this is an artifact of the finite resolution of the Herschel data. We perform a convergence test on the B211/213 filament in Taurus, by degrading the resolution of the Herschel data several times and re-estimating the filament width from the resulting column density profiles. We also compare the widths measured for the Taurus filament and other filaments from the Herschel Gould Belt survey to those found for synthetic filaments with various types of simple, idealized column density profiles. We find that the measured filament widths do increase slightly as the spatial resolution worsens and/or the distance to the filaments increases. However, this trend is entirely consistent with what is expected from simple beam convolution for filaments with density profiles that are Plummer-like and have intrinsic half-power diameters ~0.08-0.1 pc and logarithmic slopes 1.5 < p < 2.5 at large radii, as observed in many cases including the Taurus filament. Due to the presence of background noise fluctuations, deconvolution of the measured widths from the telescope beam quickly becomes inaccurate. We conclude that the typical half-power filament width ~0.1 pc measured with Herschel in nearby clouds most likely reflects the presence of a true common scale in the filamentary structure of the cold interstellar medium, at least in the solar neighborhood. We suggest that this common scale may correspond to the magnetized turbulent correlation length in molecular clouds.
