TWO EXTREME YOUNG OBJECTS IN BARNARD 1-b

Two submillimeter/millimeter sources in the Barnard 1b (B1-b) core, B1-bN and B1-bS, have been studied in dust continuum, (HCO+)-C-13 J = 1-0, CO J = 2-1, (CO)-C-13 J= 2-1, and (CO)-O-18 J = 2-1. The spectral energy distributions of these sources from the mid-IR to 7mm are characterized by very cold temperatures of T-dust < 20 K and low bolometric luminosities of 0.15-0.31L(circle dot). The internal luminosities of B1-bN and B1-bS are estimated to be < 0.01-0.03 L-circle dot and similar to 0.1-0.2 L-circle dot, respectively. Millimeter interferometric observations have shown that these sources have already formed central compact objects of similar to 100 AU sizes. Both B1-bN and B1-bS are driving the CO outflows with low characteristic velocities of similar to 2-4 km s(-1). The fractional abundance of (HCO+)-C-13 at the positions of B1-bN and B1-bS is lower than the canonical value by a factor of four to eight. This implies that a significant fraction of CO is depleted onto dust grains in the dense gas surrounding these sources. The observed physical and chemical properties suggest that B1-bN and B1-bS are in an earlier evolutionary stage than most of the known class 0 protostars. In particular, the properties of B1-bN agree with those of the first hydrostatic core predicted by the MHD simulations. The CO outflow was also detected in the mid-IR source located at similar to 15 '' from B1-bS. Since the dust continuum emission was not detected in this source, the circumstellar material surrounding this source is less than 0.01 M-circle dot. It is likely that the envelope of this source was dissipated by the outflow from the protostar that is located to the southwest of B1-b.