Recent star formation history of the Large and Small Magellanic Clouds

G. Indu* and Annapurni Subramaniamy
Indian Institute of Astrophysics, Bengaluru 560034, India

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Recent interactions between the Large and the Small Magellanic Clouds (LMC and SMC) and the Milky Way can be understood by studying their recent star formation history. We traced the age of the last star-formation event (LSFE) in the inner Large and Small Magellanic Cloud (L&SMC) using the photometric data in V and I passbands from the Optical Gravitational Lensing Experiment (OGLE-III) and the Magellanic Cloud Photometric Survey (MCPS). The spatial distribution of the age of the LSFE shows that the star-formation has shrunk to within the central regions in the last 100 Myr in both the galaxies. We detect peaks of starformation at 0 - 10 Myr and 90 - 100 Myr in the LMC, and 0 - 10 Myr and 50 - 60 Myr in the SMC. We propose that the HI gas in the LMC has been pulled to the north of the LMC in the last 200 Myr because of the gravitational attraction of our Galaxy at the time of perigalactic passage. The shifted HI gas was preferentially compressed in the north during the time interval 200 - 40 Myr and in the north-east in the last 40 Myr, owing to the motion of the LMC in the Galactic halo. The recent star-formation in the SMC is due to the combined gravitational effect of the LMC and the perigalactic passage.

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Keywords : galaxies: Magellanic Clouds – galaxies: star-formation – stars: formation – galaxies: evolution – galaxies: kinematics and dynamics