CO observations of a molecular cloud complex associated with the bright rim near VY Canis Majoris

Abstract

We present extensive CO observations of a large molecular cloud complex ( 15 pc) associated with a bright rim near the peculiar star VY CMa. CO emission peaks in a region along and adjacent to the bright rim which forms the western border of the cloud complex. This emission abruptly decreases across the bright rim, which suggests a physical association of the rim with the cloud. The molecular complex is found to consist of two clouds which have different radial velocities and physical properties. The possibility that these two clouds may be in near-collision is discussed. The physical association of the bright rim with the cloud complex indicates that the clouds are at the same distance, 1.5 kpc, as the stars which excite the rim. Since VY CMa appears to be located at the tip of the bright rim and has a velocity similar to that of the molecular cloud complex and the stars of the cluster NGC 2362, we conclude that VY CMa is also at the same distance. The resulting luminosity of VY CMa (5 x l0 L0) indicates that the star is very massive and places constraints on interpretation of its evolutionary state. Subject headings: infrared: sources - interstellar: molecules - nebulae: general - stars: individual - stars: massive - stars: variables