Volume 489, Number 1, October I 2008
|Page(s)||403 - 412|
|Published online||28 July 2008|
Abundances of four open clusters from solar stars *,**,***
Centro de Astrofisica, Universidade do Porto, Rua das Estrellas, 4150–762 Porto, Portugal
2 Aryabhatta Research Institute of Observational Sciences, Manora Peak, Nainital, 263129 Uttaranchal, India e-mail: firstname.lastname@example.org
3 European Southern Observatory, Karl Schwarzschildstr. 2, Garching bei München, Germany
4 Observatoire de Paris, 64 Avenue de l'Observatoire, 75014 Paris, France
Accepted: 16 June 2008
Aims. We present the abundance measurements of several elements (Fe, Ca, Na, Ni, Ti, Al, Cr, Si) for 20 solar-type stars belonging to four Galactic open clusters: NGC 3680, IC 4651, Praesepe, and M 67. Oxygen abundances were in addition measured for most stars in each cluster apart from IC 4651. For NGC 3680, accurate abundance determinations using high-resolution spectra covering a large spectral domain are computed for the first time.
Methods. We used UVES high-resolution, high signal-to-noise (S/N) ratio spectra and performed a differential analysis with respect to the sun, by measuring equivalent widths and assuming LTE.
Results. The most surprising result is a measurement of significant supersolar metallicity for Praesepe ([Fe/H] = 0.27±0.10). As for the other clusters, we confirm a supersolar metallicity for IC 4651 ([Fe/H] = 0.12±0.05), a solar metallicity for M 67 ([Fe/H] = 0.03±0.04) and a slight subsolar metallicity for NGC 3680 ([Fe/H] = -0.04±0.03). We find that the abundance ratios of almost all elements are solar, with the notable exception of oxygen in NGC 3680 and Praesepe, supersolar in the former cluster ([O/Fe] = 0.2±0.05) and as low as [O/Fe] = -0.4±0.1 in the latter. Observations of several objects per cluster is required to obtain robust results, especially for those elements with a limited number of suitable lines.
Key words: stars: abundances / Galaxy: open clusters and associations: individual: NGC 3680 / Galaxy: open clusters ans associations: individual: IC 4651 / Galaxy: open clusters and associations: individual: Praesepe / Galaxy: open clusters and associations: individual: M 67
Table 1 is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (220.127.116.11) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/489/403
© ESO, 2008
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.