Infall, outflow, rotation, and turbulent motions of dense gas within NGC 1333 IRAS 4

Millimeter wavelength observations are presented of NGC 1333 IRAS 4, a grou p of highly embedded young stellar objects in Perseus, that reveal motions of infall, outflow, rotation, and turbulence in the dense gas around its tw o brightest continuum objects, 4A and 4B. These data have finest angular re solution of Delta2 " (0.0034 pc) and finest velocity resolution of 0.13 km s(-1). Infall motions are seen from inverse P Cygni profiles observed in H2 CO 3(12)-2(11) toward both objects, but also in CS 3-2 and H2H+ 1-0 toward 4A, providing the least ambiguous evidence for such motions toward low-mass protostellar objects. Outflow motions are probed by bright line wings of H 2CO 3(12)-2(11) and CS 3-2 observed at positions offset from 4A and 4B, lik ely tracing dense cavity walls. Rotational motions of dense gas are traced by a systematic variation of the N2H+ line velocities, and such variations are found around 4A but not around 4B. Turbulent motions appear reduced wit h scale, given N2H+ line widths around both 4A and 4B that are narrower by factors of 2 or 3 than those seen from single-dish observations. Minimum ob served line widths of similar to0.2 km s(-1) provide a new low, upper bound to the velocity dispersion of the parent core to IRAS 4 and demonstrate th at turbulence within regions of clustered star formation can be reduced sig nificantly. A third continuum object in the region, 4B', shows no detectabl e line emission in any of the observed molecular species.