I. V. Chernyshova | Searcharxiv

arXiv1998

Accurate LTE abundances for some lambda Boo stars

High-resolution and high S/N CCD spectra were analyzed to determine accurate LTE abundances in four lambda Boo stars: pi^1 Ori, 29 Cyg, HR 8203 and 15 And. In general, 14 chemical elements were investigated. The main results are the following: all stars have a strong deficiency of the majority of investigated metals. Oxygen exhibits a moderate deficiency. The carbon abundance is close to the solar one. The results obtained support an accretion/diffusion model, which is currently adopted for the explanation of the lambda Boo phenomenon.

astro-ph↗

arXiv1998

The unusual A-star VW Ari: chemical composition revisited

Seven high-resolution and high S/N CCD spectra were used to derive elemental abundances in the atmosphere of VW Ari A (T_eff=7200, log g=3.7) which is the primary component of a visual binary system. The synthetic spectrum technique applied in the analysis allowed to reveal the following feature: the atmosphere of this star is strongly deficient in some metals, while light elements have solar-like abundances. Taking into account these results, one can suggest that VW Ari A is a lambda Boo-type star. Another argument supporting this supposition is the following: on the diagrams (b-y)-c_1, (b-y)-m_1 and (b-y)-beta (Paunzen et al. 1997), VW Ari A falls exactly in the region occupied by the lambda Boo stars. Note also, that a previous analysis (Andrievsky et al. 1995) has shown that the secondary component of VW Ari has a normal metallicity. Differences in chemical compositions of the two components appear to be due to the specific evolution of the primary VW Ari A.

astro-ph↗