2006ApJ...652.1374M

We investigate the structure of the core surrounding the recently identified deeply embedded young stellar object Barnard 1c. B1c lies within the Perseus molecular cloud at a distance of 250 pc. It is a deeply embedded core of 2.4 M_☉(Kirk et al.) and a luminosity of 4±2 L_☉. Observations (and resolutions) of ¹²CO J=1-0 (9".2x5".9), ¹³CO J=1-0, C¹⁸O J=1-0 (14".3x6".7), HCO⁺ J=1-0 (7".6x5".8), and N₂H⁺ J=1-0 (5".9x4".6) were obtained with the BIMA array, together with the continuum at 3.3 mm (6".4x4".9) and 2.7 mm (9".5x6".3). Single-dish measurements of N₂H⁺ J=1-0 and HCO⁺ J=1-0 with FCRAO reveal the larger scale emission in these lines with ∼60 resolution. The ¹²CO and HCO⁺ emission traces the outflow extending over the full field of view (2'.1), which coincides in detail with the S-shaped jet recently found in Spitzer IRAC imaging. The N₂H⁺ emission, which anticorrelates spatially with the C¹⁸O emission, originates from a rotating envelope with effective radius ∼2400 AU and mass 2.1-2.9 M_☉, as derived from the 3.3 mm continuum emission. N₂H⁺ emission is absent from a 600 AU diameter region around the young star, offset from the continuum peak. The remaining N₂H⁺ emission may lie in a coherent torus of dense material. With its outflow and rotating envelope, B1c closely resembles the previously studied object L483 mm, and we conclude that it is a protostar in an early stage of evolution, i.e., Class 0 or in transition between Class 0 and Class I. We hypothesize that heating by the outflow and star has desorbed CO from grains, which has destroyed N₂H⁺ in the inner region, and surmise that the presence of grains without ice mantles in this warm inner region can explain the unusual polarization signature observed from B1c.