EDP Sciences
Free Access
Volume 442, Number 2, November I 2005
Page(s) 563 - 566
Section Stellar structure and evolution
DOI https://doi.org/10.1051/0004-6361:20053222

A&A 442, 563-566 (2005)
DOI: 10.1051/0004-6361:20053222

Research Note

Abundances of a sample of A and F-type dwarf members of the Ursa Major Group

R. Monier

Groupe de Recherches en Astronomie et Astrophysique du Languedoc UMR 5024, Université Montpellier II, Place E. Bataillon, 34095 Montpellier, France
    e-mail: monier@graal.univ-montp2.fr

(Received 11 April 2005 / Accepted 31 May 2005)

Abundances of 11 chemical elements have been determined for 10 F and 12 A dwarfs ("normal" and chemically peculiar) bona-fide and probable members of the Ursa Major Group (age about 500 Myr). The abundances were determined in a uniform manner using a model atmosphere analysis by minimising the chi-square of grids of synthetic spectra to observed high resolution high S/N ( $R \simeq 25\,000$ and $R \simeq 70\,000 $) spectra obtained in three narrow spectral regions centered around 5075 Å, 5525 Å and 6160 Å. Specifically, Takeda's (1995) semi-automated procedure was used to derive the abundances of C, O, Na, Mg, Si, Ca, Sc, Fe, Ni, Y, and Ba, the projected rotational velocity $v_{\rm e} \sin i$ and the microturbulent velocity for each star analysed. In graphs [X/H] versus $T_{\rm eff}$, the A stars exhibit larger star-to-star variations in [Fe/H], [Ni/H], and [Si/H] than the F dwarfs do. The abundance of nickel is the only one that appears to be correlated with that of iron.

Key words: stars: abundances -- stars: rotation -- open clusters and associations: individual: Ursa Major Group

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