The VMC Survey. XXV. The 3D structure of the Small Magellanic Cloud from Classical Cepheids

V. RIPEPI, M.-R. L. CIONI, M.I. MORETTI, M. MARCONI, K. BEKKI, G. CLEMENTINI, R. DE GRIJS, J. EMERSON, M.A.T. GROENEWEGEN, V.D. IVANOV, R. MOLINARO, T. MURAVEVA, J.M. OLIVEIRA, A.E. PIATTI, S. SUBRAMANIAN, J. TH. VAN LOON

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2017 vol. 472 p. 808 - 827

0035-8711

The VISTA near-infrared Y JKs survey of the Magellanic System (VMC) is collectingdeep Ks -band time?series photometry of pulsating stars hosted by the two MagellanicClouds and their connecting Bridge. Here we present Y, J, Ks light curves for a sampleof 717 Small Magellanic Cloud (SMC) Classical Cepheids (CCs). These data, comple-mented with our previous results and V magnitude from literature, allowed us toconstruct a variety of period?luminosity and period?Wesenheit relationships, valid forFundamental, First and Second Overtone pulsators. These relations provide accurateindividual distances to CCs in the SMC over an area of more than 40 deg2. Adoptingliterature relations, we estimated ages and metallicities for the majority of the inves-tigated pulsators, finding that: i) the age distribution is bimodal, with two peaks at120±10 and 220±10 Myr; ii) the more metal-rich CCs appear to be located closer tothe centre of the galaxy. Our results show that the three?dimensional distribution ofthe CCs in the SMC, is not planar but heavily elongated for more than 25-30 kpcapproximately in the east/north-east towards south-west direction. The young andold CCs in the SMC show a different geometric distribution. Our data support thecurrent theoretical scenario predicting a close encounter or a direct collision betweenthe Clouds some 200 Myr ago and confirm the presence of a Counter-Bridge predictedby some models. The high precision three?dimensional distribution of young stars pre-sented in this paper provides a new testbed for future models exploring the formationand evolution of the Magellanic System.