Volume 544, August 2012
|Number of page(s)||11|
|Section||Stellar structure and evolution|
|Published online||24 August 2012|
A new visual – near-infrared diagnostic to estimate the metallicity of cluster and field dwarf stars
1 INAF – Osservatorio Astronomico di Roma, via Frascati 33, 00040 Monte Porzio Catone, Italy
2 IAC – Instituto de Astrofisica de Canarias, Calle via Lactea, 38200 La Laguna, Tenerife, Spain
e-mail: firstname.lastname@example.org; email@example.com
3 Department of Astrophysics, University of La Laguna, 38200 La Laguna, Tenerife, Spain
4 Università di Roma Tor Vergata, via della Ricerca Scientifica 1, 00133 Rome, Italy
e-mail: Giuseppe.Bono@roma2.infn.it; firstname.lastname@example.org
5 INAF – Osservatorio Astronomico di Collurania, via M. Maggini, 64100 Teramo, Italy
Received: 30 May 2012
Accepted: 14 July 2012
We present a theoretical calibration of a new metallicity diagnostic based on the Strömgren index m1 and on visual – near-infrared (NIR) colors to estimate the global metal abundance of cluster and field dwarf stars. To perform the metallicity calibration we adopt α-enhanced evolutionary models transformed into the observational plane by using atmosphere models computed adopting the same chemical mixture. We apply the new visual-NIR metallicity-index-color (MIC) relations to two different samples of field dwarfs and we find that the difference between photometric estimates and spectroscopic measurements is on average smaller than 0.1 dex, with a dispersion smaller than σ = 0.3 dex. We apply the same MIC relations to a metal-poor (M 92) and a metal-rich (47 Tuc) globular cluster. We find a peak of −2.01 ± 0.08 (σ = 0.30 dex) and −0.47 ± 0.01 (σ = 0.42 dex), respectively.
Key words: stars: abundances / stars: evolution / stars: Population II / stars: low-mass
© ESO, 2012
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