Time evolution of the core radius (r_c) and central density (ρ_c) for our cluster models. The central density and core radius are averaged over 0.5, 5, 50, and 500 Myr for t < 5 Myr, 5 Myr < t < 50 Myr, 50 Myr < t < 500 Myr, and t > 500 Myr, respectively. The error bars show the run-to-run variations. Each symbol indicates known star clusters near the Solar System: the present-day Pleiades, Praesepe, and Hyades, the other planet-hosting clusters (diamonds: Piskunov et al. 2007), open clusters (OC) with mass of 10² < M < 10³ M_⊙ (circles: Piskunov et al. 2007), embedded clusters (EC; squares: Lada & Lada 2003; Figer 2008; Pfalzner 2009), and youngmassive clusters (YMC; triangles: Portegies Zwart et al. 2010). Following Pfalzner (2009), we use for observed open clusters. We use the average separation from the cluster center given in Figer (2008) as r_c because the two values are comparable (Portegies Zwart et al. 2010). For embedded clusters, we consider the observed radii as their cluster sizes. We therefore adopt the half-mass radius as the radius for our embedded cluster model.