An analysis of the turbulence in the central region of M 42 through structure functions

Here, we analyse the character of the turbulence of the Huygens region in the Orion Nebula (M 42) using structure functions. We compute the second-order structure function of a high-resolution velocity map in H alpha obtained through the MUSE instrument. Ours is one of the few works that follows a mathematically sound methodology for calculating the second-order structure function of astronomical velocity fields. Because of that, our results will be useful for future comparisons with other studies of M 42 or other regions. We first analyse the probability distribution function and found it consistent with those resulting from numerical simulations of solenoidal turbulence. After a further analysis of the data, we found two possible separate motions or at least regimes in the region. This is confirmed later through the calculation of several filtered structure functions. We found that the turbulence in the Huygens region is between the Kolmogorov regime (S-2 proportional to delta r(2/3)) and the Burgers regime (S-2 proportional to delta r). We found that the turbulence in the region consists of two flow regimes that reproduce a generalized Larson's Law, S-2 similar to delta r(0.74-0.76).