Chemical abundances for ten stars in the Alpha Persei open cluster

Abstract

Abstract. Abundances of Fe, Ti, Cr, Mg and He have been determinedfor 10 stars : 5 B, 3 A, 1 F dwarfs and 1 chemically peculiar giantB8IIIp with apparent velocities ranging from 15 to 130 km.s −1 , mem-bers of the Alpha Persei open cluster (logage=7.40 yrs). The methodconsists in adjusting grids of synthetic spectra calculated with SYN-SPEC48 (Hubeny & Lanz 1992) in the wavelength range of 4450-4600˚A. The input model atmospheres are LTE, RE, plane parallel li ne blan-keted models calculated with ATLAS9 (Kurucz, 1992a). A correlationmay exist between [Fe/H] and the effective temperature. Further ob-servations of a much larger sample of B, A and F stars in this clusterare foreseen in the near future. 1 Introduction Abundance determinations for A stars have focused on chemically peculiar A starsbecause of their low apparent rotational velocities which facilitate line measure-ments. In contrast, the chemical composition of the atmospheres of normal A starsremains poorly known as their lines are broadened by rapid rotation.Interest in normal A stars has grown up recently. Using spectral line synthesis,Lemke(1989,1990), Hill & Landstreet (1993) and Hill (1995) found considerableabundance differences from star to star among the few tens normal field A dwarfsthey analysed. Consequently Varenne & Monier (1999) and Monier (2005) foundsimilar behaviour for the A dwarfs in the Hyades open cluster (age ≃ 750 Myrs)and the Ursa Major moving group (age ≃ 500 Myrs). In these two associations,the abundances of iron and other chemical elements vary over a range of 0.7 dexfor normal A dwarfs having same surface properties (same effective temperatureand surface gravity).Hui-Bon-Hoa et al. (1997) found atypical abundance patterns for the A dwarfs inthe young open cluster Alpha Persei which they tentatively identified as early Am