Abundances of Molecular Species in Barnard 68

Abundances for 5 molecules (C18O, CS, NH3, H2CO, and C3H2) and 1 molecularion (N2H+) and upper limits for the abundances of 1 molecule (13CO) and 1molecular ion (HCO+) are derived for gas within the Bok globule Barnard 68(B68). The abundances were determined using our own BIMA millimeterinterferometer data and single-dish data gathered from the literature, inconjunction with a Monte Carlo radiative transfer model. Since B68 is the onlystarless core to have its density structure strongly constrained via extinctionmapping, a major uncertainty has been removed from these determinations. Allabundances for B68 are lower than those derived for translucent and cold denseclouds, but perhaps only significantly for N2H+, NH3, and C3H2. Depletion of CStoward the extinction peak of B68 is hinted at by the large offset between theextinction peak and the position of maximum CS line brightness. Abundancesderived here for C18O and N2H+ are consistent with other, recently determinedvalues at positions observed in common.Comment: 16 pages, 1 figure, accepted by AJ, typo corrected, reference removed in Section 4.