Probing the age and structure of the nearby very young open clusters NGC 2244 and 2239

The Very young open cluster (OC) NGC2244 in the Rosette Nebula Was studied With fields, star-decontaminated Two-Micron All-Sky Survey (2MASS) photometry, which shows the main-sequence (MS) stars and ill abundant Pre-MS (PMS) population. Fundamental and Structural parameters were derived With colour-magnitude diagrams (CMDs), stellar radial density profiles (RDPs) and mass functions (MFs). Most previous Studies centred NGC 2244 close to the bright K0V star 12 Monocerotis, which is not a cluster member. Instead, the near-infrared RDP indicates a pronounced core near the 05 star HD 46150. We derive an age within 1-6 Myr, an absorption A(V) = 1.7 +/- 0.2, a distance from the Sun d(circle dot) = 1.6 +/- 0.2 kpc (approximate to 1.5 kpc Outside the solar circle), an MF slope chi = 0.91 +/- 0.13 and a total (MS+PMS) stellar mass of similar to 625 M-circle dot Its RDP is characterized by the core and cluster radii R-c approximate to 5.6 arcmin (approximate to 2.6 pc) and R-RDP approximate to 10 arcmin (approximate to 4.7 pc), respectively. Departure from dynamical equilibrium is suggested by the abnormally large core radius and the marked central stellar excess. We also investigate the elusive neighbouring OC NGC2239, which is low mass (m(MS+PMS) approximate to 301 M-circle dot), young (5 +/- 4 Myr) rather absorbed (A(V) = 3.4 +/- 0.2). and located in the background of NGC 2244 at d(circle dot) = 3.9 +/- 0.4 kpc. Its RDP follows a King-like function of R-c approximate to 0.5 arcmin approximate to 0.5 pc and R-RDP approximate to 5.0 arcmin approximate to 5.6 pc. The MF slope. chi = 1.24 +/- 0.06. is essentially Salpeter's initial mass function. NGC2244 is probably doomed to dissolution in a few 10(7) yr. Wide-field extractions and field-star decontamination increase the stellar statistics and enhance both CMDs and RDPs, which is essential for faint and bright star clusters.