Millimeter- and submillimeter-wave observations of the OMC-2/3 region. II. Observational evidence for outflow-triggered star formation in the OMC-2 FIR 3/4 region

We have observed the Orion Molecular Cloud- 2 FIR 3/ 4 region in the H13CO+ ( J 1Y0), 12CO ( J 1Y0), SiO ( v 0, J 2Y1), and CS ( J 2Y1) lines and the 3.3mmcontinuum emission with the Nobeyama Millimeter Array ( NMA) and in the CO ( J 3Y2) and CH3OH ( JK 7K Y6K) lines with Atacama Submillimeter Telescope Experiment ( ASTE). OurNMAobservations in the H13CO+ emission have revealed 0.07 pc scale dense gas associated with FIR 4 ( FIR 4 clump). The 12CO ( J 3Y2,1Y0) emission shows high- velocity blue- and redshifted components to both the northeast and southwest of FIR 3, suggesting an outflow from FIR 3 along the plane of the sky. The SiO and CH3OH emission, known as shock tracers, are detected around the interface between the outflow and FIR 4 clump. Furthermore, the 12CO ( J 1Y0) emission shows an L- shaped structure in the PV diagram. These results suggest the presence of an interaction between the outflow and FIR 4 clump. Moreover, our interferometric 3.3 mm continuum observations have first found that FIR 4 consists of 11 dusty cores at a scale of 2000 AU. The separation among these cores ( 5; 103 AU) is on the same order of the Jeans length ( 13; 103 AU), and the estimated time scale of the fragmentation ( 3: 8; 104 yr) is similar to the time scale of the outflow interaction ( 1: 4; 104 yr). We suggest that the interaction triggered the fragmentation into these dusty cores, and hence the next generation of the cluster formation in FIR 4.