A possible age-metallicity relation in the Galactic thick disk?
Författare
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.
Avdelning/ar
Publiceringsår
2004
Språk
Engelska
Sidor
969-976
Publikation/Tidskrift/Serie
Astronomy and Astrophysics
Volym
421
Fulltext
- Available as PDF - 335 kB
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Dokumenttyp
Artikel i tidskrift
Förlag
EDP Sciences
Ämne
- Astronomy, Astrophysics and Cosmology
Nyckelord
- 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/Övrigt
- ISSN: 1432-0746