A fine analysis of calcium and iron lines in the spectrum of the chromospherically active G8 dwarf ξ Bootis A.

Selected regions containing calcium lines of moderately high excitation (2.5eV) and iron lines covering a wide range of excitation in the spectrum of the chromospherically active G8 dwarf, ξ Boo A, have been recorded at a resolution of λ/{DELTA}λ=100000 and with signal/noise >=100 using a CCD array. An analysis based on weak lines and strong-line wing profiles, features likely to be formed under conditions close to LTE, has led to the following set of self-consistent atmospheric parameters: Effective temperature: T_eff_=5500+/-70K; Surface gravity: logg=4.6+/-0.1; Logarithmic iron abundance (relative to the Sun): 000[Fe/H]=-0.15 +/-0.05; Logarithmic calcium abundance (relative to the Sun): 000[Ca/H]=-0.13+/-0.05; Microturbulence: ξ=1.8 +/-0.1km/s. A comparison between observed and computed profiles for the extremely strong ionized calcium line at 8542A confirms that ξ Boo A is slightly metal poor compared to the Sun. Results for ξ Boo A are compared to those obtained by Drake & Smith (1993) for the similar chromospherically active dwarf ɛ Eri.