2000ApJ...542..344P

We present the aperture synthesis imaging of C₃H₂ 2₁₂-1₀₁ and HCO⁺ 1-0 lines and of continuum emission at λ=3.4 mm toward the class 0 young stellar object IRAS 18148-0440 in the L483 molecular cloud. The continuum emission is detected at the IRAS position at a level of 16 mJy, indicating a compact source with a mass of ∼0.13 M_☉. The C₃H₂ delineates an envelope near the IRAS position, with a size of ∼3000 AUx2000 AU in R.A. and decl. directions, respectively. A velocity gradient detected only along the axis of outflow can be explained in terms of free-fall motion of the envelope. The HCO⁺ line wing extends up to the velocity of ±6 km.s^–1 relative to the systemic one, and the high-velocity material shows a symmetric bipolarity and extends over 2' or 0.1 pc along the east-west direction. It is found that the outflow material is clumpy and the opening angle is widest for the slowest moving component. The core component of the HCO⁺ 1-0 line exhibits an anti-infall asymmetry not only in interferometric but also in single dish observations. It is attributable to the slow isotropic outward motion of gas between the flattened envelope and the collimated outflow.