Local Molecular Gas toward the Aquila Rift Region

Abstract

Abstract We present the results of a ∼250 square degrees CO mapping (+26° ≲ l ≲ +50° and −5° ≲ b ≲ +5°) toward the Aquila Rift region at a spatial resolution of ∼50″ and a grid spacing of 30″. The high dynamic range CO maps with a spectral resolution of ∼0.2 km s−1 display highly structured molecular cloud (MC) morphologies with valuable velocity information, revealing complex spatial and dynamical features of the local molecular gas. In combination with the MWISP CO data and the Gaia DR2, distances of the main MC structures in the local ISM are well determined toward the Aquila Rift region. We find that the total MC mass within 1 kpc is about ≳4.1 × 105 in the whole region. In fact, the mass of the molecular gas is dominated by the W40 giant molecular cloud (GMC) at ∼474 pc (∼1.4 × 105 ) and the GMC complex G036.0+01.0 at ∼560–670 pc (∼2.0 × 105 ), while the MCs at ∼220–260 pc have gas masses of ∼102–103 . Interestingly, an ∼80 pc long filamentary MC G044.0–02.5 at a distance of ∼404 pc shows a systematic velocity gradient along and perpendicular to the major axis of the filament. The H i gas with enhanced emission has similar spatial morphologies and velocity features compared to the corresponding CO structure, indicating that large-scale converging H i flows are probably responsible for the formation of the MC. Meanwhile, the long filamentary MC consists of many sub-filaments with lengths ranging from ∼0.5 pc to several pc, as well as prevalent networks of filaments in other large-scale local MCs.