A Dark-Cloud Complex in Aquila: Small Molecular Clouds Possibly Associated with the Aquila Rift

Abstract

Abstract A 12CO(J = 1−0) survey for local molecular clouds was performed toward dark clouds in Aquila (26° < l ≤ 42° and −25° ≤ b < −2°) by using the 4-meter millimeter wave telescope, NANTEN, at Las Campanas Observatory, Chile. A cloud complex consisting of 64 small clouds has been discovered in −25° ≲ b ≲ −12°; at a distance of 220 pc, its height from the galactic plane is ∼ 50–100 pc and the total mass is ∼ 4 × 103M⊙. The spatial and velocity distributions of the complex suggest that it may be connected to the Great Rift in Aquila. This complex, as a whole, has a significantly large virial mass compared with the mass derived from the CO intensities by an order of magnitude, though H I gas of ∼ 104M⊙, possibly associated, may contribute to bind them gravitationally. The individual CO clouds have velocity dispersion and mass similar to those of the high-latitude clouds; also, the clouds are not in gravitational equilibrium. There is no indication of active star formation.