The filamentary structures in the CO emission toward the Milky Way disk

Abstract

We present a statistical study of the filamentary structure orientation in the CO emission observations obtained in the Milky Way Imaging Scroll Painting survey in the range 25.°8 < l < 49.°7, |b| ≤ 1.°25, and −100 < vLSR < 135 km s−1. We found that most of the filamentary structures in the 12CO and 13CO emission do not show a global preferential orientation either parallel or perpendicular to the Galactic plane. However, we found ranges in Galactic longitude and radial velocity where the 12CO and 13CO filamentary structures are parallel to the Galactic plane. These preferential orientations are different from those found for the HI emission. We consider this an indication that the molecular structures do not simply inherit these properties from parental atomic clouds. Instead, they are shaped by local physical conditions, such as stellar feedback, magnetic fields, and Galactic spiral shocks.