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Astron. Astrophys. 358, L21-L23 (2000)

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Letter to the Editor

Removal of the calcium underabundance in cool metal rich Galactic disk dwarfs *

P. Thorén

Uppsala Astronomical Observatory, Box 515, 751 20, Uppsala, Sweden

Received 9 March 2000 / Accepted 26 April 2000


An apparent Ca underabundance for cool metal rich disk dwarfs was derived by Feltzing & Gustafsson (1998). This was suggested to be a NLTE effect, following the prediction by Drake (1991). New NLTE calculations with MARCS atmospheres and opacities show that deviations from LTE are very small and can not explain the underabundance. It is shown that the underabundance was primarily due to erroneously calculated atomic line broadening parameters (van der Waals broadening). Part of the underabundance was also due to the decision not to change photometrically determined stellar parameters to satisfy the Fe I excitation balance.

Key words: atomic data – stars: abundances – stars: late-type

* Based on observations made at ESO, La Silla

Send offprint requests to: Patrik Thorén (patrik.thoren@astro.uu.se)

© European Southern Observatory (ESO) 2000

Online publication: June 26, 2000