2006ApJ...637..860W

We report ``infall asymmetry'' in the HCO⁺(1-0) and (3-2) lines toward NGC 1333, extended over ∼0.39 pc², a larger extent than has been reported before for any star-forming region. The infall asymmetry extends over a major portion of the star-forming complex, and is not limited to a single protostar, a single dense core, or a single spectral line. It seems likely that the infall asymmetry represents inward motions, and that these motions are physically associated with the complex. Both blue-asymmetric and red-asymmetric lines are seen, but in both the (3-2) and (1-0) lines of HCO⁺ the vast majority of the asymmetric lines are blue, indicating inward motions. The (3-2) line, tracing denser gas, has the spectra with the strongest asymmetry; these spectra are associated with the protostars IRAS 4A and 4B, which most likely indicates that a warm central source is affecting the line profiles. The (3-2) and (1-0) lines usually have the same sense of asymmetry in common positions, but their profiles differ significantly, and the (1-0) line appears to trace motions on much larger spatial scales than does the (3-2) line. Line profile models fit the spectra well, but do not strongly constrain their parameters. The mass accretion rate of the inward motions is of order 10^–4 M_☉/yr1, similar to the ratio of stellar mass to cluster age.