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Thomas Bensby. Profile photo.

Thomas Bensby

Senior lecturer

Thomas Bensby. Profile photo.

A possible age-metallicity relation in the Galactic thick disk?

Author

  • Thomas Bensby
  • Sofia Feltzing
  • Ingemar Lundström

Summary, in English

A sample of 229 nearby thick disk stars has been used to investigate theexistence of an age-metallicity relation (AMR) in the Galactic thickdisk. The results indicate that that there is indeed an age-metallicityrelation present in the thick disk. By dividing the stellar sample intosub-groups, separated by 0.1 dex in metallicity, we show that the medianage decreases by about 5-7 Gyr when going from [Fe/H] ≈ -0.8 to[Fe/H] ≈ -0.1. Combining our results with our newly publishedα-element trends for a local sample of thick disk stars that showsignatures from supernovae type Ia (SN Ia), we draw the conclusion thatthe time-scale for the peak of the SN Ia rate is of the order of 3-4 Gyrin the thick disk. The tentative evidence for a thick disk AMR that wepresent here also has implications for the thick disk formationscenario; star-formation must have been an ongoing process for severalbillion years. This appears to strengthen the hypothesis that the thickdisk originated from a merger event with a companion galaxy that puffedup a pre-existing thin disk.Based on data obtained with the Hipparcos satellite.

Department/s

  • Lund Observatory

Publishing year

2004

Language

English

Pages

969-976

Publication/Series

Astronomy and Astrophysics

Volume

421

Document type

Journal article

Publisher

EDP Sciences

Topic

  • Astronomy, Astrophysics and Cosmology

Keywords

  • stars: Hertzsprung-Russell (HR) and C-M diagrams
  • stars: kinematics
  • Galaxy: disk
  • Galaxy: formation
  • Galaxy: solar neighbourhood
  • Galaxy: kinematics and dynamics

Status

Published

ISBN/ISSN/Other

  • ISSN: 1432-0746