2003ApJ...590..932T

We have carried out mapping observations of the molecular core associated with the young Class 0 protostar, IRAM 04191+1522, in the CH₃OH (J_K=2_K-1_K) and C³⁴S (J=2-1) lines, using the 45 m telescope at Nobeyama Radio Observatory. Our observations have revealed that there is a condensation associated with the protostar, elongated in the east-west direction mostly perpendicular to the axis of the associated CO outflow. Its size and mass are estimated to be 0.07x0.04 pc and 2.3 M_☉, respectively, from the CH₃OH data. In addition to the elongated envelope, two compact (∼0.03 pc) condensations were found in the CH₃OH line at the southern edge of the elongated envelope, where the blueshifted CO outflow emerging from the protostar is located. In contrast to the elongated envelope, those compact CH₃OH condensations show much larger line width (up to 2.0 km/s), with centroid velocities blueshifted by ∼0.8 km/s. The compact condensations have momenta (∼0.06 M_☉km/s) comparable to that of the blueshifted molecular outflow. In addition, they are gravitationally unbound, and most probably will dissipate eventually. These results suggest that the compact condensations are probably formed in the course of interaction between the outflow and the ambient gas surrounding the protostar and that such interaction may cause dissipation of a part of the ambient gas. No drastic, localized enhancement of the CH₃OH abundance is, however, observed toward the compact condensations, implying that there seems to be no significant shock heating at the compact condensations, in spite of the interaction with the outflow. This may be because the CO outflow velocity (<10 km/s) is too low to cause effective heating to release CH₃OH on dust grains into the gas phase.