Dynamical histories of the IC 348 and NGC 1333 star-forming regions in Perseus

摘要

We present analyses of the spatial distributions of stars in the young (1–3 Myr) star-formingudregions IC 348 and NGC 1333 in the Perseus giant molecular cloud. We quantify the spatialudstructure using the Q-parameter and find that both IC 348 and NGC 1333 are smoothudand centrally concentrated with Q-parameters of 0.98 and 0.89, respectively. Neither regionudexhibits mass segregation (MSR = 1.1+0.2 −0.3 for IC 348 and MSR = 1.2+0.4 −0.3 for NGC 1333,udwhere MSR ∼ 1 corresponds to no mass segregation) nor do the most massive stars reside inudareas of enhanced stellar surface density compared to the average surface density, accordingudto the LDR method. We then constrain the dynamical histories and hence initial conditionsudof both regions by comparing the observed values to N-body simulations at appropriate ages.udStars in both regions likely formed with subvirial velocities that contributed to merging of substructureudand the formation of smooth clusters. The initial stellar densities were no higher thanudρ ∼ 100–500 M pc−3 for IC 348 and ρ ∼ 500–2000 M pc−3 for NGC 1333. These initialuddensities, in particular that of NGC 1333, are high enough to facilitate dynamical interactionsudthat would likely affect ∼10 per cent of protoplanetary discs and binary stars.udKey