IAUS379: Dynamical Masses of Local Group Galaxies

The Magellanic Bridge is a tidally-stripped structure located between the Magellanic Clouds and contains hundreds of stellar clusters and associations, which can help understanding the origin and evolution of the entire Magellanic Clouds-Milky Way (MW) system. Two main competing models describe the formation of the pair LMC-SMC: the LMC captured the SMC about 2 Gyr ago and they are in a bound orbit around the MW, or it is an old interacting sys- tem in its first perigalactic passage, falling into the MW potential ~2 Gyr ago. The Bridge should have been formed during a collision between the Clouds around 200 Myr ago, imply- ing kinematic signatures, as well as age and metallicity gradients along its extension. This work combines deep photometric data from VISCACHA and SMASH surveys in order to ex- plore this question, by homogeneously deriving age, metallicity, distance, structural parame- ters and mass of 35 Bridge objects with modern statistical tools such as Markov chain Monte Carlo and machine learning. In particular, the mass determination corrected by completeness can help to estimate the Bridge stellar mass and constrain the dynamical models. A spectro- scopic follow-up in the CaII triplet region is also carried out for clusters older than 1 Gyr in the Bridge and other SMC regions, to derive metallicity and radial velocity which, combined with Gaia proper motions, allow us to obtain a 6D phase-space vector. Preliminary results show a good agreement between VISCACHA and SMASH data and also that, despite the presence of some old objects at larger distances, the clusters in the middle of the Bridge are younger (~ 10-100 Myr) and more metal-rich than those closer to the SMC Wing. In this poster, we will review the recent results of the VISCACHA collaboration, present a detailed approach to age and metallicity gradients in the Bridge, and discuss the evidence on the most probable for- mation model of the pair LMC-SMC.