L. Inno Abstract

The 3D Structure of the Magellanic Clouds Traced by Classical Cepheids

L. Inno (ESO), N. Matsunaga, G. Bono, F. Caputo, R. Buonanno, C. D. Laney, and M. Marconi

Classical Cepheids are robust tracers of the Magellanic Cloud (MC) young stellar populations, since they are bright intermediate-mass stars in the blue loop phase. They obey to well-defined Period-Wesenheit (PW) relations, that are reddening independent and minimally affected by metallicity. The new near-infrared (NIR) data sets collected by the IRFS/SIRIUS survey together with the Optical Gravitational Lensing Experiment (OGLE III) data sets allow us to study the three-dimensional distribution of more than 7000 Cepheids in the MCs. By using NIR and Optical-NIR PW relations, we estimated the relative distances of ~3300 (LMC) and ~4400 (SMC) Cepheids, including fundamental, first overtone and double-mode pulsators (LMC: 1840 FU, 1202 FO, 60 FU/FO, 199 FO/SO;SMC: 2587 FU,1579 FO, 55 FU/FO,195 FO/SO).

We found that the LMC has a complex vertical structure along the line of sight, with evidence of a non-planar matter distribution. The SMC is more homogeneous, its thickness increases along the line-of-sight and the increase in the spread appears to be connected with the LMC. To constrain the kinematics and the metallicity distribution of the young populations we already collected with VIMOS at VLT low-resolution spectra for more than 900 Cepheids (~300 LMC and ~600 SMC). We plan to present preliminary results concerning both the radial velocities and the abundances.