We have carried out mapping observations of the molecular core associated with the young Class 0 protostar , IRAM 04191+1522 , in the CH _ { 3 } OH ( J _ { K } =2 _ { K } –1 _ { K } ) and C ^ { 34 } S ( 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 0.07 pc \times 0.04 pc and 2.3 M _ { \odot } , respectively , from the CH _ { 3 } OH data .
In addition to the elongated envelope , two compact ( \sim 0.03 pc ) condensations were found in the CH _ { 3 } OH 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 CH _ { 3 } OH condensations show much larger line width ( up to 2.0 km s ^ { -1 } ) with centroid velocities blueshifted by \sim 0.8 km s ^ { -1 } .
The compact condensations have momenta ( \sim 0.06 M _ { \odot } 
km s ^ { -1 } ) 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 CH _ { 3 } OH 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 ^ { -1 } ) is too low to cause effective heating to release CH _ { 3 } OH on dust grains into gas phase .