1997A&A...322..234R

A spectroscopic analysis of the rapidly oscillating chemically peculiar star γ Equ yields T_eff=7700K, logg=4.20, a microturbulence and v.sin i which cannot be determined reliably, but which must be close to zero, because line broadening can be modelled by magnetic field effects alone. A mean magnetic field modulus of B=4.0kG is estimated by comparing synthetic Zeeman pattern with observations. This value provides another phase point for magnetic field variations of γ Equ, a CP2 star with the longest hitherto known magnetic field period of about 77 years. For a simple dipolar field geometry, the angle between the line of sight and the magnetic axis ≃130° (or ≃50°). We discuss in some detail the problems for abundance determinations in the presence of a strong magnetic field and we increase substantially the number of ions to 42, for which abundances are now available. In particular, we obtain a more reliable abundance of log(Eu/N_tot)=-10.24, and find Fe and the light elements, C to Ca, to have nearly solar abundances. Co is clearly overabundant, and Nb and Mo are the most overabundant elements in γ Equ relative to the Sun.