标题： 用红外观测探测OMC1中的湍流 显示英文标题

标题： Probing Turbulence with Infrared Observations in OMC1

摘要： 给出了猎户分子云中湍流速度结构的统计分析，尺度范围从70个天文单位到30000个天文单位。 结果基于K带S(1)v=1-0线（2.121微米）中激波和光激发H2的红外法布里-珀罗干涉观测结果，并涉及暖扰动气体的动力学特征。 观测表明，Larson大小-线宽关系在所研究的最小尺度上得到遵守，将该关系的有效范围扩展了将近两个数量级。 构建了速度概率分布函数（PDF），显示出扩展的指数翼，提供了间歇性的证据，进一步由速度分布的偏度和峰度支持。 作为滞后函数，构造了速度差的PDF的方差和峰度。 方差显示出近似的滞后幂律依赖性，指数显著低于Kolmogorov值，并且在低于2000 AU时的偏差归因于外流以及可能与OMC1中的低质量恒星形成相关的盘状结构。 峰度显示出强偏离高斯速度场，提供了小滞后时间速度相关性的证据。 结果与Eggers & Wang（1998）的半经验模拟结果准确一致。 此外，还分析了170个单独的H2发射团块，其大小在500到2200 AU之间。 这些团块在PDF和方差函数方面表现出相当大的多样性。 我们的分析构成了首次对恒星形成尺度湍流速度场的表征，并提供了一个数据集，恒星形成区域的模型应努力重现。 显示英文摘要

摘要： A statistical analysis is presented of the turbulent velocity structure in the Orion Molecular Cloud at scales ranging from 70 AU to 30000 AU. Results are based on IR Fabry-Perot interferometric observations of shock and photon-excited H2 in the K-band S(1) v=1-0 line at 2.121micron and refer to the dynamical characteristics of warm perturbed gas. Observations establish that the Larson size-linewidth relation is obeyed to the smallest scales studied here extending the range of validity of this relationship by nearly 2 orders of magnitude. The velocity probability distribution function (PDF) is constructed showing extended exponential wings, providing evidence of intermittency, further supported by the skewness and kurtosis of the velocity distribution. Variance and kurtosis of the PDF of velocity differences are constructed as a function of lag. The variance shows an approximate power law dependence on lag, with exponent significantly lower than the Kolmogorov value, and with deviations below 2000AU which are attributed to outflows and possibly disk structures associated with low mass star formation within OMC1. The kurtosis shows strong deviation from a gaussian velocity field, providing evidence of velocity correlations at small lags. Results agree accurately with semi-empirical simulations in Eggers & Wang (1998). In addition, 170 individual H2 emitting clumps have been analysed with sizes between 500 and 2200 AU. These show considerable diversity with regard to PDFs and variance functions. Our analysis constitutes the first characterization of the turbulent velocity field at the scale of star formation and provide a dataset which models of star-forming regions should aim to reproduce.