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Photo of Paul McMillan

Paul McMillan

Researcher

Photo of Paul McMillan

The VMC survey - XLVIII. Classical cepheids unveil the 3D geometry of the LMC

Author

  • Vincenzo Ripepi
  • Laurent Chemin
  • Roberto Molinaro
  • Maria Rosa L. Cioni
  • Kenji Bekki
  • Gisella Clementini
  • Richard De Grijs
  • Giulia De Somma
  • Dalal El Youssoufi
  • Léo Girardi
  • Martin A.T. Groenewegen
  • Valentin Ivanov
  • Marcella Marconi
  • Paul J. McMillan
  • Jacco Th Van Loon

Summary, in English

We employed the VISTA near-infrared YJKssurvey of the Magellanic System (VMC) to analyse the Y, J, and Ks light curves of δCepheid stars (DCEPs) in the Large Magellanic Cloud (LMC). Our sample consists of 4408 objects accounting for 97 per cent of the combined list of OGLE IV and Gaia DR2 DCEPs. We determined a variety of period-luminosity (PL) and period-Wesenheit PW relationships for Fundamental (F) and First Overtone (1O) pulsators. We discovered for the first time a break in these relationships for 1O DCEPs at P= 0.58 d. We derived relative individual distances for DCEPs in the LMC with a precision of ∼1 kpc, calculating the position angle of the line of nodes and inclination of the galaxy: θ = 145.6 ± 1.0 deg and i = 25.7 ± 0.4 deg. The bar and the disc are seen under different viewing angles. We calculated the ages of the pulsators, finding two main episodes of DCEP formation lasting ∼40 Myr which happened 93 and 159 Myr ago. Likely as a result of its past interactions with the SMC, the LMC shows a non-planar distribution, with considerable structuring: the bar is divided into two distinct portions, the eastern and the western displaced by more than 1 kpc from each other. Similar behaviour is shown by the spiral arms. The LMC disc appears 'flared' and thick, with a disc scale height of h ∼0.97 kpc. This feature can be explained by strong tidal interactions with the Milky Way and/or the Small Magellanic Cloud or past merging events with now disrupted LMC satellites.

Department/s

  • Lund Observatory

Publishing year

2022-05

Language

English

Pages

563-582

Publication/Series

Monthly Notices of the Royal Astronomical Society

Volume

512

Issue

1

Document type

Journal article

Publisher

Oxford University Press

Topic

  • Astronomy, Astrophysics and Cosmology

Keywords

  • galaxies: photometry
  • galaxies: stellar content
  • galaxies: structure
  • Magellanic Clouds
  • stars: distances
  • stars: variables: Cepheids

Status

Published

ISBN/ISSN/Other

  • ISSN: 0035-8711