SMALL-SCALE STRUCTURE OF CANDIDATES FOR PROTOSTELLAR COLLAPSE .1. BIMA OBSERVATIONS OF L1527 AND CB-54

Aperture synthesis observations of L1527 and CB 54 were made in the (C O)-C-13 and (CO)-O-18 J = 1 --> 0 lines using the BIMA interferometers , in order to probe the small-scale structure of the gas distribution and to test the collapse picture in these two sources. In L1527, a bip olar outflow is detected in (CO)-C-13 with an opening angle of 50 degr ees and its axis in the plane of the sky along the east-west direction . The profile difference between the (CO)-C-13 and (CO)-O-18 J = 1 --> 0 lines toward the center position is consistent with the signature o f infall, as suggested by previous single-dish observations of L1527. In CB 54, a bipolar outflow is seen in (CO)-C-13; one of the redshifte d outflow peaks is less than 10 '' from the center position, making it difficult to pick out possible signatures of infall. We have made rad iative transfer models for L1527 based on the collapse solution of a r otating cloud by Terebey, Shu, & Cassen. The best-fit parameters are a s follows: the effective sound speed, a = 0.25 km s(-1); the infall ra dius, r(inf) = 0.026 pc; the H2CO abundance, X(H2CO) = 4 x 10(-9); and the (CO)-O-18 abundance, X((CO)-O-18) = 1.4 x 10(-7). The model can r eproduce the observed profiles of single-dish observations and also th e qualitative feature of the interferometric observations. Comparisons are made with other models for L1527 in the literature.