We present an analysis of velocity-resolved near-IR molecular hydrogen observations of a variety of protostellar outflows with very different energetics, degrees of collimation, and morphologies. Observations in the 2.12 μm line of H2 were obtained using an IR Fabry-Pérot interferometer with a spectral resolution of 23 km s-1. The integrated flux-velocity diagrams for each outflow show a flat spectrum for low velocities followed by a decreasing power law dF/dv ∝ vγ, with γ between -1.8 and -2.6, for velocities higher than a clearly defined break velocity at 2-17 km s-1. Contrary to shock model predictions, it is shown that the H2 intensity is constant with velocity. We argue that the flux-velocity relation can then be interpreted as a mass-velocity relation, in striking similarity to the power-law mass spectra observed in CO outflows. By comparing H2 and CO mass-velocity spectra, it is shown that there is a velocity regime in which both molecules coexist and produce similar γ-values. Evolution effects in outflows appear as a correlation between outflow length and γ; as outflows age, the spectra becomes steeper. Our results support a common physical origin for both CO and H2 emission and a strong association between the molecular outflows traced in each molecule.
展开▼
机译:我们提出了一种具有不同能量,准直度和形态的各种原恒星流出的速度分辨近红外分子氢观测值的分析。使用IRFabry-Pérot干涉仪以23 km s-1的光谱分辨率获得了H2 2.12μm线的观测值。每次流出的集成通量-速度图显示了低速的平坦频谱,其后是幂率递减的dF / dv ∝vγ,其中γ介于-1.8和-2.6之间,且速度高于在2-17处明确定义的断裂速度公里s-1。与冲击模型预测相反,证明了H2强度随速度恒定。我们认为通量-速度关系可以解释为质量-速度关系,这与在CO流出物中观察到的幂律质谱具有惊人的相似性。通过比较H2和CO的质量谱,可以看出存在一种速度机制,其中两个分子共存并产生相似的γ值。流出中的演化效应表现为流出长度与γ之间的相关性。随着流出年龄的增长,光谱变得越来越陡峭。我们的结果支持CO和H2排放的共同物理起源以及每个分子中追踪的分子流出之间的强关联。
展开▼