Naomi HIRANO (ASIAA); Shigehisa TAKAKUWA (Kagoshima Univ.); Kengo TOMIDA (Osaka Univ.); Kazuya SAIGO (NAOJ); Masahiro MACHIDA (Kyushu Univ.); Koji TOMISAKA (NAOJ); Masaaki HIRAMATSU (NAOJ); Tien-Hao Hsieh (ASIAA); Nadia Murillo (Leiden Observatory)
Two extremely young protostars, B1-bN and B1-bS, and a Class 0 protostar, B1-c have been observed with the Atacama Large Millimeter/submillimeter Array at an angular resolution of ~0.2". The CH3OH 5_k--4_k lines at E_up < 50 K and H2CO 3(1,2)--2(1,1) line trace the outflows from these protostars. In the case of B1-c, the CH3OH and H2CO delineate the edges of the outflow lobes traced by the CO. In contrast, the outflows from B1-bN and B1-bS traced by the CH3OH and H2CO show significant different features. The outflow from B1-bN consists of the highly collimated blueshifted lobe and spatially compact redshifted lobe. The axes of the blue- and redshifted lobes are misaligned by 30 deg. The radial velocity of the blueshifted lobe increases linearly as a function of distance from the central star. The high velocity component along the axis is surrounded by the lower velocity component. These results suggest that the lobe was formed by the single explosive event that happened at ~1000 yrs ago. The outflow from B1-bS consists of three pairs of collimated lobes, each of which has similar velocity structure as that of the blueshifted lobe in B1-bN. As in the case of the B1-bN outflow, the axes of the blue- and redshifted pairs are also misaligned, The terminal velocities of the B1-bN and B1-bS outflow reaches ~9 km/s and ~8 km/s (without inclination correction), respectively, both of which are much higher than that of the outflow from the first hydrostatic core. This indicates that both B1-bN and B1-bS have already experienced the second collapse.