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Astron. Astrophys. 323, 809-818 (1997)


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The [Fe/H] distribution of a volume limited sample of solar-type stars and its implications for galactic chemical evolution *

F. Favata 1, G. Micela 2 and S. Sciortino 2

1 Astrophysics Division - ESA/ESTEC, Postbus 299, 2200 AG Noordwijk, The Netherlands (fabio.favata@astro.estec.esa.nl)
2 Istituto e Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, I-90134 Palermo, Italy (gmicela@oapa.astropa.unipa.it,ssciortino@oapa.astropa.unipa.it)

Received 27 September 1996 / Accepted 6 January 1997

Abstract

We present [Fe/H] determinations for a volume-limited sample of G and K dwarfs from the Gliese catalog of nearby stars. The [Fe/H] values were determined from the Fe I lines present in [FORMULA] Å wide high resolution ([FORMULA]) spectra taken around the Li I 6707.8 Å line, through an equivalent width analysis based on the latest Kurucz model atmospheres.

The resulting abundance distribution, corrected for disk heating effects, is compared to recent models of galactic chemical evolution. The surprising result is that, while the abundance distribution of solar-type dwarfs hotter than [FORMULA] K and the derived chemical evolution parameters (in particular the rate of Fe enrichment and the abundance spread at a given age) are compatible with previous determinations of the same quantities, dwarfs cooler than 5100 K show a lack of metal-poor ([FORMULA]) objects, implying chemical evolution parameters (using the same model) not compatible with the ones derived for the hotter stars. Possible explanations for this fact are discussed, critically considering possible biases present in the parent sample, as well as each of the assumptions made in the chemical evolution model and in particular the assumption that the birth rate will be constant with time and independent of stellar mass.

Key words: stars: abundances – stars: late-type – stars: formation – Galaxy: evolution

* Based on observations collected at the ESO La Silla observatory

Send offprint requests to: F. Favata

© European Southern Observatory (ESO) 1997

Online publication: May 26, 1998

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