MOLECULAR LINE OBSERVATIONS OF A COMET-SHAPED CLOUD (LBN-437) IN THE LACERTA OB1 ASSOCIATION

Two prominent nuclei of a large, comet-like (10 pc in length) dust and gas complex, located in the Lacerta Constellation (l similar to 96 de grees, b similar to -15 degrees), have been observed in molecular line s of CO, NH3 and H2CO. We will refer to the whole system as the LBN 43 7 complex. It lies at the edge of the youngest subgroup of the Lac OB1 association and is associated with this young group of stars. The com etary head, condensation A, contains reflection nebulae and a group of faint LkH alpha stars, among them LkH alpha 233. H2CO(1(11)-1(10)) (C O)-C-13(1-0) and (2-1) line maps show an elongated configuration of si ze similar to 2 x 0.5 pc and a mass of 150-300 M.. NH3(1,1) and (2,2) inversion line observations of Condensation A reveal the existence of a cold (10 K) and dense (3 10(4) cm(-3)) core of elliptical shape. The mass and linear dimensions of this NH3 clump are 15 M., similar to 0. 16 pc (semi-major axis) and similar to 0.10 pc (semi-minor axis). From IRAS 60-100 mu m images and (CO)-C-12(1-0) line data, we infer dust a nd gas temperatures of similar to 37 K for the surrounding low-column density, far-m emitting material. It is concluded that Condensation A consists of a cold dense core, from which newly formed Her emission li ne stars have formed. This is surrounded by a lower density envelope w hose warm surface is heated externally by a nearby B star (HD 213976). Condensation B, lying near the end of the cometary ''tail'', was mapp ed in H2CO absorption, although NH3 emission lines were not detected.