Revisiting the Velocity Dispersion–Size Relation in Molecular Cloud Structures 后印本

摘要: Structures in molecular ISM are observed to follow a power-law relation between the velocity dispersion and spatial size, known as Larson's first relation, which is often attributed to the turbulent nature of molecular ISM and imprints the dynamics of molecular cloud structures. Using the 13CO (J = 1–0) data from the Milky Way Imaging Scroll Painting survey, we built a sample with 360 structures having relatively accurate distances obtained from either the reddened background stars with Gaia parallaxes or associated maser parallaxes, spanning from 0.4 to ∼15 kpc. Using this sample and about 0.3 million pixels, we analyzed the correlations between velocity dispersion, surface/column density, and spatial scales. Our structure-wise results show power-law indices smaller than 0.5 in both the σv–Reff and σv–Reff · Σ relations. In the pixel-wise results, the  is statistically scaling with the beam physical size (Rs ≡ ΘD/2) in form