The Ara OB1 Association and its molecular complex

Abstract

Carbon monoxide (12CO J= 1 ?¨ 0) line observations toward the OB association Ara OB1 are reported. The molecular features that are likely to be associated with the OB-association span a velocity range from -28 to -20 km s-1. The most negative radial velocities are observed along NGC 6188 (also known as the Rim Nebula). The main CO structures, labeled E and F in Fig. ref{arnal:COobs}, have radial velocities of about -23.5 and -21.8 km s-1, respectively. The former harbors the IRAS source IRAS 16362-4845 and the infrared cluster RCW 108-IR. The observations at intermediate resolution show noticeable changes in shape, peak intensity and full width at half maximum in the line profiles observed toward structures E and F. The large line widths, about 7.5 km s-1, found toward structure E very likely reflect the interaction of RCW 108-IR with its surrounding molecular gas. A scale down version of this phenomenon is also found toward structure F