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 groupof highly-embedded young stellar objects in Perseus, that reveal motions ofinfall, outflow, rotation, and turbulence in the dense gas around its twobrightest continuum objects, 4A and 4B. These data have finest angularresolution of approximately 2" (0.0034 pc) and finest velocity resolution of0.13 km/s. Infall motions are seen from inverse P-Cygni profiles observed inH2CO 3_12-2_11 toward both objects, but also in CS 3-2 and N2H+ 1-0 toward 4A,providing the least ambiguous evidence for such motions toward low-massprotostellar objects. Outflow motions are probed by bright line wings of H2CO3_12-2_11 and CS 3-2 observed at positions offset from 4A and 4B, likelytracing dense cavity walls. Rotational motions of dense gas are traced by asystematic variation of the N2H+ line velocities, and such variations are foundaround 4A but not around 4B. Turbulent motions appear reduced with scale, givenN2H+ line widths around both 4A and 4B that are narrower by factors of 2 or 3than those seen from single-dish observations. Minimum observed line widths ofapproximately 0.2 km/s provide a new low, upper bound to the velocitydispersion of the parent core to IRAS 4, and demonstrate that turbulence withinregions of clustered star formation can be reduced significantly. A thirdcontinuum object in the region, 4B', shows no detectable line emission in anyof the observed molecular species.Comment: LateX, 51 pages, 9 figures, accepted by Ap