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Lennart Lindegren. Profile picture.

Lennart Lindegren

Professor

Lennart Lindegren. Profile picture.

Estimating the age–metallicity distribution of a stellar sample from the probability distributions of the individual stars

Author

  • Christian L. Sahlholdt
  • Lennart Lindegren

Summary, in English

Estimating age distributions, or star formation histories, of stellar populations in the Milky Way is important in order to study the evolution of trends in elemental abundances and kinematics. We build on previous work to develop an algorithm for estimating the age-metallicity distribution which uses the full age-metallicity probability density functions (PDFs) of individual stars. No assumptions are made about the shape of the underlying distribution, and the only free parameter of the algorithm is used to ensure a smooth solution. In this work, we use individual age-metallicity PDFs from isochrone fitting of stars with known metallicities. The method is tested with synthetic samples and is found to recover the input age-metallicity distribution more accurately than the distribution of individually estimated ages and metallicities. The recovered sample age distribution (SAD) is always more accurate than the distribution of individual ages, also when restricted to the most precise individual ages. By applying the method to the stars in the Geneva-Copenhagen survey, we detect a possible minimum in the star formation history of the Solar neighbourhood at an age of 10 Gyr which is not seen in the distribution of individual ages. Although we apply the method only to age-metallicity distributions, the algorithm is described more generally and can in principle be applied in other parameter spaces. It is also not restricted to individual parameter distributions from isochrone fitting, meaning that an SAD can be estimated based on individual age PDFs from other methods such as asteroseismology or gyrochronology.

Department/s

  • Lund Observatory - Has been reorganised

Publishing year

2021-01

Language

English

Pages

845-864

Publication/Series

Monthly Notices of the Royal Astronomical Society

Volume

502

Issue

1

Document type

Journal article

Publisher

Oxford University Press

Topic

  • Astronomy, Astrophysics and Cosmology

Keywords

  • methods: statistical
  • stars: fundamental parameters
  • Hertzsprung-Russell and colour-magnitude diagrams
  • Galaxy: stellar content
  • Astrophysics - Instrumentation and Methods for Astrophysics
  • Astrophysics - Astrophysics of Galaxies
  • Astrophysics - Solar and Stellar Astrophysics

Status

Published

Project

  • Stellar ages for Galactic Archaeology: Methods and Applications

ISBN/ISSN/Other

  • ISSN: 0035-8711