K dwarfs and the chemical evolution of the Solar cylinder

E. Kotoneva; C. Flynn; C. Chiappini; F. Matteucci

doi:10.1046/j.1365-8711.2002.05825.x

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arXiv · astro-ph/0206446

K dwarfs and the chemical evolution of the Solar cylinder

E. Kotoneva·C. Flynn·C. Chiappini·F. Matteucci

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Abstract

K-dwarfs have life-times older than the present age of the Galactic disc, and are thus ideal stars to investigate the disc's chemical evolution. We have developed several photometric metallicity indicators for K dwarfs, based an a sample of accurate spectroscopic metallicities for 34 disc and halo G and K dwarfs. The photometric metallicities lead us to develop a metallicity index for K dwarfs based only on their position in the colour absolute-magnitude diagram. Metallicities have been determined for 431 single K dwarfs drawn from the Hipparcos catalog, selecting the stars by absolute magnitude and removing multiple systems. The sample is essentially a complete reckoning of the metal content in nearby K dwarfs. We use stellar isochrones to mark the stars by mass, and select a subset of 220 of the stars which is complete in a narrow mass interval. We fit the data with a model of the chemical evolution of the Solar cylinder. We find that only a modest cosmic scatter is required to fit our age metallicity relation. The model assumes two main infall episodes for the formation of the halo-thick disc and thin disc respectively. The new data confirms that the solar neighbourhood formed on a long timescale of order 7 Gyr.

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E. Kotoneva, C. Flynn, C. Chiappini, F. Matteucci. 2002-06-26. K dwarfs and the chemical evolution of the Solar cylinder. https://doi.org/10.1046/j.1365-8711.2002.05825.x

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