The Magellanic Clouds are the nearest gas-rich dwarf satellites of the Milky Way and illustrate a typical example of an early phase of a minor merger event, the collision of galaxies that differ in mass by at least a factor of ten. The
Magellanic Clouds play a major role in supplementing material to the Milky Way and their irregular morphology has been severely shaped by interactions between each other, and with the Milky Way. The Magellanic Clouds are embedded in a large neutral gas envelope and and linked by a 'bridge' while a 'stream' spanning a large distance across the sky departs from them. These are likely tidal and/or ram pressure features.
Thanks to their proximity (50-60 kpc) we can study the content of the Magellanic Clouds, stars and gas, in great detail and major world-wide facilities have invested large amounts of telescope time to observe the faintest stars, to study their distribution, and to measure their age, distance, motion, and chemistry. Maria-Rosa Cioni is leading the most sensitive near-infrared multi-epoch imaging survey of the Magellanic Clouds (VMC; Cioni et al. 2011) aimed at deriving the spatially resolved star formation history and the three-dimensional geometry of the system. She also participates in two major optical imaging programs: the STEP survey (Ripepi et al. 2014) aimed at reconstructing the history of star formation of the SMC and Bridge, and the SMASH survey , aimed at detecting stellar debris in the outermost regions of the Magellanic Clouds system. Increasingly large samples of spectra are also being collected, to obtain the radial velocity and chemical information that can better characterise the stellar populations and remove potential biases, and Maria-Rosa is coordinating future observations with new multi-object facilities, including MOONs and 4MOST.
The most recent results obtained from the VMC survey. The proper motion of the Small Magellanic Cloud, of the Galactic globular cluster 47 Tucanae, and of the Milky Way stars in the line-of-sight are represented. The different colours refer to regions at progressively larger distances from the centre of the cluster (inner - black, middle - cyan, outer - magenta). For details see Cioni et al. 2015.