Journal Article

Chemical composition of evolved stars in the open cluster NGC 2506

Šarūnas Mikolaitis, Gražina Tautvaišienė, Raffaele Gratton, Angela Bragaglia and Eugenio Carretta

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 416, issue 2, pages 1092-1098
Published in print September 2011 | ISSN: 0035-8711
Published online September 2011 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2011.19106.x
Chemical composition of evolved stars in the open cluster NGC 2506

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In this study we present abundances of 12C, 13C, N, O and up to 26 other chemical elements in two first-ascent giants and two core-helium-burning ‘clump’ stars of the open cluster NGC 2506. Abundances of carbon were derived using the C2 Swan (0,1) band head at 5635.5 Å. The wavelength interval 7940–8130 Å, with strong CN features, was analysed in order to determine nitrogen abundances and carbon isotope ratios. The oxygen abundances were determined from the [O i] line at 6300 Å. NGC 2506 was found to have a mean [Fe/H]=−0.24 ± 0.05 (standard deviation). Compared with the Sun and other dwarf stars of the Galactic disc, mean abundances in the investigated clump stars suggest that carbon is depleted by about 0.2 dex, nitrogen is overabundant by about 0.3 dex and other chemical elements have abundance ratios close to solar. The C/N and 12C/13C ratios are lowered to 1.25 ± 0.27 and 11 ± 3, respectively.

Keywords: stars: abundances; stars: atmospheres; stars: horizontal branch; open clusters and associations: individual: NGC 2506

Journal Article.  3946 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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