A Spectroscopic Study of the Bp-Star θ Aur

Abstract

The atmosphere parameters, spectral variability and the magnetic field geometry of the Bp-star θ Aur are evaluated from 30 coude-spectrograms. We adopt T_e= 10 800 K and lg g=3.40 (with lower reliability of lg g). The equivalent widths of the metalic lines show a relatively great scattering which troubles the period search. The bast fit to our data gives the period P = 3.620^d, but the variability is clearly seen only for SiII lines. The uncertainties in the star parameters obtained bring to a great uncertainty in the magnetic dipole geometry: i = 86°+ 39° and β = 18° + 80°. We adopt the most plausible star parameters to be: R = 3.8 R⊙ M = 3.5 M⊙, i = 80°, β = 20°, Bp = 1 KGs.