ALMA Observations of the ρ Ophiuchus B2 Region. I. Molecular Outflows and Their Driving Sources

Abstract We present the results of ALMA mosaic observations of dust continuum and 12CO (J = 2−1), 13CO (J = 2−1), and C18O (J = 2−1) molecular lines toward the ρ Ophiuchus B2 region. The 1.3 mm dust continuum image made from the combined 12 and 7 m array data reveals not only the dense cores identified by past single-dish observations but also their detailed internal substructures. The 12CO (J = 2−1) images show very complex structures of protostellar outflows. They suggest that the gigantic outflow lobes in Oph B2 are presumably driven at least by two protostars, EL 32 and EL 33. We do not detect clear high-velocity components associated with the Class I protostar SST c2d J162730.9−242733 and the flat-spectrum object SST c2d J162721.8−242727. In addition, we find interesting striations with 15″ (≈2000 au) separations in both the 12CO and 13CO channel maps. The CO striations appear to be roughly parallel to the magnetic field direction, and we speculate that the directions of the striations may follow the magnetic field in the envelope of Oph B2.