Profiling filaments: comparing near-infrared extinction and submillimetre data in TMC-1
Profiling filaments: comparing near-infrared extinction and submillimetre data in TMC-1
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DOI：
10.1051/0004-6361/201219573
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发表时间：
2012-06
影响因子：
6.5
通讯作者：
J. Malinen;M. Juvela;M. Rawlings;D. Ward-Thompson;P. Palmeirim;P. Andre'
中科院分区：
文献类型：
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作者：
J. Malinen;M. Juvela;M. Rawlings;D. Ward-Thompson;P. Palmeirim;P. Andre'
上下文星际细丝是星星形成过程的重要组成部分。为了理解长丝的结构和形成，长丝横截面轮廓通常用所谓的Plummer轮廓函数拟合。目前，这种剖面往往是接近亚毫米的研究，特别是与赫歇尔。如果无法获得这些数据，那么使用地基近红外观测来研究细丝的特性会更方便。目标。我们比较了近红外消光和亚毫米观测获得的灯丝配置文件，以了解是否可以使用近红外观测得到可靠的配置文件。方法.我们使用的J-，H-和K-波段数据的灯丝TMC-1的北部，从背景恒星的颜色过剩的消光图。我们还使用2 MASS数据的这和另一个灯丝在TMC-1。我们比较普卢默配置文件从这些消光图与赫歇尔尘埃发射图。我们提出了两种根据近红外数据估计轮廓的新方法：Plummer轮廓在一定偏移范围内拟合恒星的AV中位数或直接拟合单个恒星的AV。我们比较这些方法的模拟。结果在模拟中，消光图和新方法给出的正确结果在中等密度（ρc = 10 4 - 10 5 cm −3）的± 10-20%之内。直接拟合单个恒星的数据通常比灭绝图给出更准确的结果，并且可以在更高的密度下工作。在对真实的观测值的剖面拟合中，普卢默参数的值通常在1/12的因子内（最多1/15的因子）相似。虽然参数值可以有很大的不同，长丝质量的估计通常保持准确的百分之几十内。我们的TMC-1的结果与早期的结果与SCUBA和ISO是一致的。高分辨率的近红外数据提供了更多的细节，但2 MASS数据可以用来估计近似的轮廓。结论.近红外消光图可以作为亚毫米观测的替代方法来分析细丝。恒星的直接拟合也可以是剖面分析中的一个有价值的工具。但是，Plummer轮廓参数并不总是受到很好的约束，因此在进行拟合和解释结果时应谨慎。在普卢默参数的评估中，还可以利用粉尘排放和近红外数据的独立性以及相关置信区域形状的差异。
Context. Interstellar filaments are an important part of the star formation process. In order to understand the structure and formation of filaments, the filament cross-section profiles are often fitted with the so-called Plummer profile function. Currently this profiling is often approached with submillimetre studies, especially with Herschel. If these data are not available, it would be more convenient if filament properties could be studied using groundbased near-infrared (NIR) observations. Aims. We compare the filament profiles obtained by NIR extinction and submillimetre observations to find out if reliable profiles can be derived using NIR observations. Methods. We use J-, H-, and K-band data of a filament north of TMC-1 to derive an extinction map from colour excesses of background stars. We also use 2MASS data of this and another filament in TMC-1. We compare the Plummer profiles obtained from these extinction maps with Herschel dust emission maps. We present two new methods to estimate profiles from NIR data: Plummer profile fits to median AV of stars within certain offset or directly to the AV of individual stars. We compare these methods by simulations. Results. In simulations the extinction maps and the new methods give correct results to within ∼10–20% for modest densities (ρc = 10 4 –10 5 cm −3 ). The direct fit to data on individual stars usually gives more accurate results than the extinction map, and can work in higher density. In the profile fits to real observations, the values of Plummer parameters are generally similar to within a factor of ∼2 (up to a factor of ∼5). Although the parameter values can vary significantly, the estimates of filament mass usually remain accurate to within some tens of per cent. Our results for TMC-1 are in good agreement with earlier results obtained with SCUBA and ISO. High resolution NIR data give more details, but 2MASS data can be used to estimate approximate profiles. Conclusions. NIR extinction maps can be used as an alternative to submm observations to profile filaments. Direct fits of stars can also be a valuable tool in profiling. However, the Plummer profile parameters are not always well constrained, and caution should be taken when making the fits and interpreting the results. In the evaluation of the Plummer parameters, one can also make use of the independence of the dust emission and NIR data and the difference in the shapes of the associated confidence regions.