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Scientific Highlights with the SMA

Two Extremely Young Objects in Barnard 1-b

B1-b, which is the most prominent dense core in the B1 region (top panel), harbors 2 submm/mm continuum sources labeled B1-bN and B1-bS. Both sources have no counterpart in mid infrared even in the 24 micron band of the Spitzer MIPS (bottom-left panel). The Spectral energy distributions (SEDs)of these sources from mid-IR to 7 mm revealed that these sources have very low temperatures of < 20 K and low bolometric luminosities of 0.15--0.3 L_sun. The internal luminosities of B1-bN and B1-bS are estimated to be < 0.01--0.03 Lsun and ~0.1--0.2 Lsun, respectively. Both B1-bN and B1-bS are driving the CO outflows with low characteristic velocities of ~2--4 km/s (bottom-right panel). The very low temperatures, the very low intrinsic luminosities, and the low-velocity outflows imply that B1-bN and B1-bS are in the earlier evolutionary stage than most of the known Class 0 protostars. Especially, the properties of B1-bN agree with those of the first hydrostatic core predicted by the MHD simulations.


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