Young stars in the periphery of the Large Magellanic Cloud

Abstract

Despite their close proximity, the complex interplay between the two Magellanic Clouds, theMilky Way and the resulting tidal features, is still poorly understood. Recent studies haveshown that the Large Magellanic Cloud (LMC) has a very extended disc strikingly perturbedin its outskirts. We search for recent star formation in the far outskirts of the LMC, out to∼30◦from its centre. We have collected intermediate-resolution spectra of 31 young star candidatesin the periphery of the LMC and measured their radial velocity, stellar parameters, distanceand age. Our measurements confirm membership to the LMC of six targets, for which theradial velocity and distance values match well with those of the Cloud. These objects are allyoung (10–50 Myr), main-sequence stars, projected between 7◦and 13◦from the centre ofthe parent galaxy. We compare the velocities of our stars with those of a disc model, andfind that our stars have low to moderate velocity differences with the disc model predictions,indicating that they were formedin situ. Our study demonstrates that recent star formationoccurred in the far periphery of the LMC, where thus far only old objects were known. Thespatial configuration of these newly formed stars appears ring-like with a radius of 12 kpc anda displacement of 2.6 kpc from the LMC’s centre. This structure, if real, would be suggestiveof a star formation episode triggered by an off-centre collision between the Small MagellanicCloud and the LMC’s disc.