The Recent Star Formation History of the Magellanic Clouds Traced by Classical Cepheids

We present a new theoretical calibration of the period-age (PA) relations for classical Cepheids in the Magellanic Clouds (MCs), by adopting a homogeneous set of nonlinear, convective pulsation models and a detailed set of intermediate-mass evolutionary tracks. The new PA relations were applied to the sample of MC classical Cepheids collected by OGLE III to investigate their recent star formation history. We found that the MCs experienced an ongoing star formation activity during the past 400 Myrs and the two systems show strong similarities. Moreover, we also found that the star formation was quite homogeneous when moving from the central bar regions to the more external regions. Current findings support dynamical models predicting that the MCs are binary galaxies in their first infall towards the Galaxy. The shift in mean age between the Large Magellanic Cloud (LMC, ̃140 Myr) and the Small Magellanic Cloud (SMC, ̃230 Myr) is due to an intrinsic evolutionary property. The SMC is more metal-poor than the LMC and the extent in temperature of the blue loops is larger in the former system....