FUNDAMENTAL PARAMETERS OF AP-STARS 78 VIR (HD118022) AND AX CVN (HD110066)

Abstract

Determination of the fundamental parameters of stars is one of the main tasks of astrophysics. Magnetic chemically peculiar (Ap) stars HD118022 (78 Vir) and HD110066 (AX CVn) have similar strengths of the surface magnetic field 3 -4 kGs..The atmospheric analysis of the these two Ap stars results in the determination of the eective temperatures Teff , surface gravities lg g , radii R=Ro and luminosities L=L, as well as element abundances by self-consistent way. It allows to dene more accurately their position on the Hertzsprung-Russell diagram. Additionally, we derived the vertical distribution (stratication) of Fe and Cr elements for all spectra. Our analysis is based on high-resolution (R = 65000), high S/N spectra of 78Vir obtained with the NARVAL spectropolarimeter attached to the 2 m telescope of the Pic du Midi observatory (7 phases of rotation), and on one spectrum at the phase of magnetic maximum which was obtained with the UVES (R = 80000) spectrograph of the VLT. For star AX CVn the spectra were obtained with ESPaDOnS (R = 81000) spectropolarimeter of CFHT. HD 118022 and HD 110066 show nearly similar element abundance pattern and element stratification.