The Gaia -ESO Survey: Open clusters in Gaia -DR1: A way forward to stellar age calibration

Forskningsoutput: TidskriftsbidragArtikel i vetenskaplig tidskrift


Context. Determination and calibration of the ages of stars, which heavily rely on stellar evolutionary models, are very challenging, while representing a crucial aspect in many astrophysical areas. Aims. We describe the methodologies that, taking advantage of Gaia-DR1 and the Gaia-ESO Survey data, enable the comparison of observed open star cluster sequences with stellar evolutionary models. The final, long-term goal is the exploitation of open clusters as age calibrators. Methods. We perform a homogeneous analysis of eight open clusters using the Gaia-DR1 TGAS catalogue for bright members and information from the Gaia-ESO Survey for fainter stars. Cluster membership probabilities for the Gaia-ESO Survey targets are derived based on several spectroscopic tracers. The Gaia-ESO Survey also provides the cluster chemical composition. We obtain cluster parallaxes using two methods. The first one relies on the astrometric selection of a sample of bona fide members, while the other one fits the parallax distribution of a larger sample of TGAS sources. Ages and reddening values are recovered through a Bayesian analysis using the 2MASS magnitudes and three sets of standard models. Lithium depletion boundary (LDB) ages are also determined using literature observations and the same models employed for the Bayesian analysis. Results. For all but one cluster, parallaxes derived by us agree with those presented in Gaia Collaboration (2017, A&A, 601, A19), while a discrepancy is found for NGC 2516; we provide evidence supporting our own determination. Inferred cluster ages are robust against models and are generally consistent with literature values. Conclusions. The systematic parallax errors inherent in the Gaia DR1 data presently limit the precision of our results. Nevertheless, we have been able to place these eight clusters onto the same age scale for the first time, with good agreement between isochronal and LDB ages where there is overlap. Our approach appears promising and demonstrates the potential of combining Gaia and ground-based spectroscopic datasets.


  • S. Randich
  • E. Tognelli
  • R. Jackson
  • R. D. Jeffries
  • S. Degl'Innocenti
  • E. Pancino
  • P. Re Fiorentin
  • A. Spagna
  • G. Sacco
  • A. Bragaglia
  • L. Magrini
  • P. G.Prada Moroni
  • E. Alfaro
  • E. Franciosini
  • L. Morbidelli
  • V. Roccatagliata
  • H. Bouy
  • L. Bravi
  • F. M. Jiménez-Esteban
  • C. Jordi
  • E. Zari
  • G. Tautvaišiene
  • A. Drazdauskas
  • S. Mikolaitis
  • G. Gilmore
  • A. Vallenari
  • S. Koposov
  • A. Korn
  • A. Lanzafame
  • R. Smiljanic
  • A. Bayo
  • G. Carraro
  • M. T. Costado
  • U. Heiter
  • A. Hourihane
  • P. Jofré
  • J. Lewis
  • L. Monaco
  • L. Prisinzano
  • L. Sbordone
  • S. G. Sousa
  • C. C. Worley
  • S. Zaggia
Enheter & grupper
Externa organisationer
  • INAF - Osservatorio Astrofisico di Arcetri
  • Keele University
  • INAF Osservatorio Astronomico di Bologna
  • CSIC Instituto de Astrofísica de Andalucía (IAA)
  • CSIC Centro de Astrobiologia (INTA)
  • University of Barcelona
  • Vilnius University
  • University of Cambridge
  • INAF - Osservatorio Astronomico di Padova
  • Uppsala universitet
  • University of Catania
  • Nicolaus Copernicus Astronomical Center of the Polish Academy of Sciences
  • University of Padova
  • Diego Portales University
  • INAF Palermo Astronomical Observatory
  • European Southern Observatory Santiago
  • Centre for Astrophysics of the University of Porto
  • University of Pisa
  • INFN Section of Pisa
  • INAF - Osservatorio Astrofisico di Torino
  • Bordeaux Observatory
  • University of Florence
  • Leiden University
  • University of Valparaíso
  • Andrés Bello National University

Ämnesklassifikation (UKÄ) – OBLIGATORISK

  • Astronomi, astrofysik och kosmologi


TidskriftAstronomy and Astrophysics
StatusPublished - 2018 apr 1
Peer review utfördJa

Related projects

Gerry Gilmore, Sofia Randich, Sofia Feltzing, Thomas Bensby, Louise Howes, Pieter Gruyters, Nils Ryde, Edita Stonkute & Gregory Ruchti


Projekt: ForskningInternationellt samarbete

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