Abundances of a sample of A and F-type dwarf members of the Ursa Major Group
Abstract
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 ≃ 25 000 and R ≃ 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 ve sin i and the microturbulent velocity for each star analysed. In graphs [X/H] versus T_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.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- November 2005
- DOI:
- 10.1051/0004-6361:20053222
- Bibcode:
- 2005A&A...442..563M
- Keywords:
-
- stars: abundances;
- stars: rotation;
- open clusters and associations: individual: Ursa Major Group