EPoS Contribution
EPoS Contribution
Two extremely young protostars in Barnard 1

Naomi Hirano
ASIAA, Taipei, Taiwan
We have observed the continuum and molecular line emission from nearby (D~230 pc) dense molecular cloud core Barnard 1-b (B1-b) using the Nobeyama Millimeter Array (NMA) and the Submillimeter Array (SMA). The continuum emission from two sources, B1-bN and B1-bS, are clearly detected in 3 mm, 1.3 mm, and 1.1 mm, indicating that compact objects similar to class 0 protostars have already been formed there. However, neither B1-bN nor B1-bS has a counterpart in the Spitzer mid-IR image even at 24 and 70 micron. The Spectral energy distributions of these sources imply that they are extremely cold (T_dust = 13--15 K) and low luminosity (L_bol ~0.3 L_sun) objects. The N2D+ J=3-2 and H13CO+ J=1-0 line data observed with the SMA and NMA, respectively, are supplemented by the single-dish data in order to fill the short-spacing information. The N2D+ map shows two compact structures that correspond to B1-bN and B1-bS, respectively, and spatially extended structure. Strong N2D+ emission at B1-bN and B1-bS suggests that the N2D+ molecule can survive in the gas phase at low temperature and high density condition. On the other the H13CO+ map is featureless without any compact structure, and almost identical to the single-dish map. The lack of H13CO+ emission in the vicinities of B1-bN and B1-bS is probably due to the depletion of the H13CO+ molecule onto dust grains, as in the case of pre-stellar cores. The observed physical and chemical properties suggest that B1-bN and B1-bS are in the very beginning stage of protostellar evolution, which is between pre-stellar core and class 0 protostar.
Fang-Chun Liu, MPIfR, Germany
Yun-Hsin Huang, NTU, Taiwan
Shih-Oing Lai, NTHU, Taiwan
Tomofumi Umemoto, NAOJ, Japan