A large-scale survey of NGC 1333

Abstract

We observed the clustered star forming complex NGC 1333 with the BIMA and FCRAO telescopes in the transitions HCO+(1-0) and N2H+(1-0) over an 11' × 11' area with resolution ~10'' (0.015 pc). The N2H+ emission follows very closely the submillimeter dust continuum emission, while HCO+ emission appears more spatially extended and also traces outflows. We have identified 93 N2H+ cores using the CLUMPFIND algorithm, and we derive N2H+ core masses between 0.05 and 2.5 Msun, with uncertainties of a factor of a few, dominated by the adopted N2H+ abundance. From a comparison with virial masses, we argue that most of these N2H+ cores are likely to be bound, even at the lowest masses, suggesting that the cores do not trace transient structures, and implies the entire mass distribution consists of objects that can potentially form stars. We find that the mass distribution of N2H+ cores resembles the field star IMF, which suggests that the IMF is locked in at the prestellar stage of evolution. We find that the N2H+ cores associated with stars identified from Spitzer infrared images have a flat mass distribution. This might be because lower mass cores lose a larger fraction of their mass when forming a star. Even in this clustered environment, we find no evidence for ballistic motions of the cores relative to their lower density surroundings traced by isotopic CO emission, although this conclusion must remain tentative until the surroundings are observed at the same high resolution as the N2H+.