Film boiling around immersed objects in a subcooled liquid is critical in various engineering applications and offer many scientific issues. After presenting a numerical solver able to simulate film boiling around a solid obstacle and some preliminary validations of this solver, we propose a comprehensive study based on the Direct Numerical Simulation (DNS) to investigate accurately on the dynamical and heat transfer effects inside the vapor film. After defining two Jakob numbers related respectively to the wall superheat and to the liquid, a parametric study is performed by varying both dimensionless numbers. The simulations allow to visualize the flow structure inside the vapor film and to predict angular variations of the local Nusselt number along the solid wall. In particular, spatial distributions of the local heat flux, related to variations of the film thickness along the solid obstacle, are observed with higher values at the bottom part of the sphere due to buoyancy effect. The simulations also provide accurate data on the global Nusselt number variation with respect to the Jakob numbers and confirm the dominance of conduction heat transfer inside the vapor film. Finally, the study also explores the equilibrium between vaporization and condensation processes which leads to the stabilization of the vapor film around the solid obstacle. This research enhances the understanding of subcooled film boiling and offers new data for film boiling model validation.