Spectroscopic survey of γ Doradus stars – I. Comprehensive atmospheric parameters and abundance analysis of γ Doradus stars

Abstract

We present a spectroscopic survey of known and candidate γ Doradus stars. The high-resolution, high signal-to-noise spectra of 52 objects were collected by five different spectrographs. The spectral classification, atmospheric parameters (<it>T</it><inf>eff</inf>, log <it>g</it>, ξ), <it>v</it>sin <it>i</it> and chemical composition of the stars were derived. The stellar spectral and luminosity classes were found between G0–A7 and IV–V, respectively. The initial values for <it>T</it><inf>eff</inf> and log <it>g</it> were determined from the photometric indices and spectral energy distribution. Those parameters were improved by the analysis of hydrogen lines. The final values of <it>T</it><inf>eff</inf>, log <it>g</it> and ξ were derived from the iron lines analysis. The <it>T</it><inf>eff</inf> values were found between 6000 K and 7900 K, while log <it>g</it> values range from 3.8 to 4.5 dex. Chemical abundances and <it>v</it>sin <it>i</it> values were derived by the spectrum synthesis method. The <it>v</it>sin <it>i</it> values were found between 5 and 240 km s−1. The chemical abundance pattern of γ Doradus stars were compared with the pattern of non-pulsating stars. It turned out that there is no significant difference in abundance patterns between these two groups. Additionally, the relations between the atmospheric parameters and the pulsation quantities were checked. A strong correlation between the <it>v</it>sin <it>i</it> and the pulsation periods of γ Doradus variables was obtained. The accurate positions of the analysed stars in the Hertzsprung–Russell diagram have been shown. Most of our objects are located inside or close to the blue edge of the theoretical instability strip of γ Doradus.