Volume 372, Number 2, June III 2001
|Page(s)||544 - 550|
|Section||Interstellar and circumstellar matter|
|Published online||15 June 2001|
Pulsational constraints to the metallicity gradient in the Galactic disk
Osservatorio Astronomico di Roma, Via di Frascati 33, 00040 Monteporzio Catone, Italy
2 Osservatorio Astronomico di Capodimonte, Via Moiariello 16, 80131 Napoli, Italy
3 Observatoire de Genève, Switzerland e-mail: firstname.lastname@example.org; email@example.com; firstname.lastname@example.org;
Corresponding author: M. Marconi, email@example.com
Accepted: 26 March 2001
BVI data of Galactic Cepheids observed in the solar neighborhood and in the outer disk are analyzed on the basis of nonlinear, non-local and time-dependent convective pulsating models computed for different assumptions on the chemical composition. We show that the theoretical color-color, period-luminosity, and period-luminosity-color relations, as predicted by the models with varying metal content, provide the way to simultaneously estimate the true distance modulus and the metal content Z of each individual variable. On this basis, we estimate that the metallicity distribution of Cepheids with Galactocentric distances d from ~6 to ~19 kpc can be represented by a linear gradient of dex kpc-1, which is close to previous empirical determinations based on Cepheids, Planetary Nebulae and HII regions. However, our results are not excluding a different scenario, such as a two-zone model with a discontinuity in metallicity near kpc (see Twarog et al. 1997).
Key words: stars: variables: Cepheids / stars: oscillations / stars: distances
© ESO, 2001
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