Accepted for publication in The Astrophysical Journal A NEW METHOD FOR THE ASSESSMENT OF AGE AND AGE-SPREAD OF PRE–MAIN-SEQUENCE STARS IN YOUNG STELLAR ASSOCIATIONS OF THE MAGELLANIC CLOUDS?, †

We present a new method for the evaluation of the age and age-spread among pre–main-sequence (PMS) stars in star-forming regions in the Magellanic Clouds, accounting simultaneously for photomet-ric errors, unresolved binarity, differential extinction, stellar variability, accretion and crowding. The application of the method is performed with the statistical construction of synthetic color-magnitude diagrams using isochrones from two families of PMS evolutionary models. We convert each isochrone into 2D probability distributions of artificial PMS stars in the CMD by applying the aforementioned biases that dislocate these stars from their original CMD positions. A maximum-likelihood technique is then applied to derive the probability for each observed star to have a certain age, as well as the best age for the entire cluster. We apply our method to the photometric catalog of ∼ 2 000 PMS stars in the young association LH 95 in the Large Magellanic Cloud, based on the deepest HST/ACS imaging ever performed toward this galaxy, with a detection limit of V ∼ 28, corresponding to M ∼ 0.2 M. We assume the Initial Mass Function and reddening distribution for the system, as they are previously derived by us. Our treatment shows that the age determination is very sensitive to the considered grid of evolutionary models and the assumed binary fraction. The age of LH 95 is found to vary fro