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Abstract

I built a Master Catalogue of stars towards the Magellanic Clouds (MC2) based on multiwavelength cross-identifications of the DENIS, 2MASS, GSC-II and UCAC point source catalogues. I derived important results on the astro-photometric accuracy and calibration of the cross-identified catalogues. The MC2 can be queried on-line through a dedicated web interface I designed to handle its composite nature. See http://vizier.u-strasbg.fr/MC2/. I produced multispectral views of the LMC where its various populations discriminate remarkably well in colour-colour and colour-magnitude diagrams based on both infrared and visible wavelengths. The MC2 provides an unprecedented basis for the study of stellar populations in the Magellanic Clouds and for further cross-identifications with catalogues at other wavelengths.

I calibrated the absolute magnitudes of the B-type stars in the near-infrared, as a function of their spectral types. I combined high quality Hipparcos-based distance measurements with homogeneous photometry from the near-infrared 2MASS point sources. I corrected the data from extinction effect and assessed by means of simulations the contribution of various measurement errors and physical effects (binarity, rotation) to the scatter observed in the calibration. It is a mandatory step towards the determination of the structure of the young Galactic disk and of the distances and properties of young open clusters revealed by large area infrared surveys such as 2MASS.

I started a morphological and multiwavelength analysis of ionized regions and their stars in the LMC, observed in narrow-band imaging. Massive stars and their reciprocal interaction with the surrounding interstellar medium enable to gain insight into the local star formation history and stellar contents of these regions and to obtain a sketch of their dynamical evolution.