Hipparcos and the age of the Galactic disc |
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Authors: | Raul Jimenez,Chris Flynn,& Eira Kotoneva |
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Affiliation: | Institute for Astronomy, University of Edinburgh, Royal Observatory Edinburgh, Blackford Hill, Edinburgh EH9 3HJ,;Tuorla Observatory, Piikkiö, FIN-21500, Finland |
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Abstract: | We use the Hipparcos colour–magnitude diagram of field stars with Tycho colours to make a new minimum age estimate for the Galactic disc. The method is based on fits to the red envelope of subgiants in the Hipparcos colour–magnitude diagram with synthetic isochrones covering the range of disc metal abundance. The colours and luminosities of the isochrones as a function of abundance are checked using new techniques involving 'red-clump' stars in the giant branch region and on the main sequence using G and K dwarfs. We derive a minimum disc age of 8 Gyr, in good agreement with other methods. |
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Keywords: | stars: abundances stars: evolution stars: late-type Galaxy: evolution |
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