STRUCTURE OF L-1521B - CO OBSERVATIONS OF A DENSE CORE IN TAURUS

L 1521B is a dense core near B216 in one of the long filaments of the Taurus molecular cloud complex. The core is not associated with any kn own IR sources and shows no apparent signs of star formation. We have mapped the cloud in (CO)-C-13(1-0) and (CO)-O-18(1-0) using a grid of 1'. This area, altogether some 140 square are minutes, contains the de nsity maximum as well as some parts of the filament north-west of the cloud centre. At the centre position we derive a column density N((CO) -O-18)=4.10(15)cm(-2) and an optical depth of about 1.3 for (CO)-O-18. Using a value of r=140 pc for the distance we estimate that the total mass contained within a radius of 3' around the density maximum is ab out 20 solar masses. The visual extinction has been estimated from the (CO)-O-18 column density and through star counts of two fields observ ed at 2.2 mu m. The extinction in the central region is A(v) approxima te to 20(m). We have also mapped part of the B216 filament about one d egree north-west of the centre of L 1521B in (CO)-O-18(1-0). This area contains two IRAS point sources which are probably associated with cl ass I protostars.