Kinematics of subclusters in star cluster complexes: imprint of their parental molecular clouds

Abstract

Star cluster complexes such as the Carina Nebula can have formed in turbulent giant molecular clouds. We perform a series of $N$-body simulations starting from subclustering initial conditions based on hydrodynamic simulations of turbulent molecular clouds. These simulations finally result in the formation of star cluster complexes consisting of several subclusters (clumps). We obtain the inter-clump velocity distribution, the size of the region, and the mass of the most massive cluster in our simulated complex and compare the results with observed ones (the Carina Nebula and NGC 2264). The one-dimensional inter-clump velocity dispersion obtained from our simulations is $2.9\pm0.3$ and $1.4\pm0.4$ km s$^{-1}$ for the Carina- and NGC 2264-like models, respectively, which are consistent with those obtained from Gaia Data Release 2: 2.35 and 0.99 km s$^{-1}$ for the Carina Nebula and NGC 2264, respectively. We estimate that the masses of the parental molecular clouds for the Carina Nebula and the NGC 2264 are $4\times 10^5$ and $4\times 10^4M_{\odot}$, respectively.