CO and near IR observations of a filamentary cloud, L43

Abstract

Detailed observations of the filamentary cloud L43 have been made. Maps are presented for /sup 12/CO and /sup 13/CO emission and for star counts on a hypersensitized Kodak IV-N plate. We determine that for thermalized CO, N (/sup 13/CO)/A/sub V/approx.1.5 x 10/sup 15/ cm/sup -2/ mag/sup -1/ everywhere in the cloud except for the highly opaque core, where N (/sup 13/CO)/A/sub V/ or =12 mag. The cloud mass is estimated to be > or =14 M/sub sun/ in the core. A small observed velocity gradient is insufficient by a factor of at least 12 to allow any rotational support for the cloud, and is also much less than that expected for free-fall collapse along its length. It appears as if this filament is evolving towards a configuration with a centralized concentration of mass. The time scale for this to happen is indeterminate, but it appears to be longer than a free-fall collapse time. Two stars have faint reflection nebulae at the periphery of L43. If these stars formed in the cloud, then small-scale star formation may occur without the free-fall collapse of a surrounding cloud.