ABUNDANCE ANALYSIS OF ROAP STARS .3. GAMMA-EQUULEI

A spectroscopic analysis of the rapidly oscillating chemically peculia r star gamma Equ yields T-eff=7700K, log g=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 eff ects alone. A mean magnetic field modulus of B=4.0kG is estimated by c omparing synthetic Zeeman pattern with observations. This value provid es another phase point for magnetic field variations of gamma Equ, a C P2 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 approximate to 130 deg (or approxi mate to 50 deg). We discuss in some detail the problems for abundance determinations in the presence of a strong magnetic field and we incre ase substantially the number of ions to 42, for which abundances are n ow available. In particular, we obtain a more reliable abundance of lo g(Eu/N-tot)=-10.24, and find Fe and the light elements, C to Ca, to ha ve nearly solar abundances. Co is clearly overabundant, and Nb and Mo are the most overabundant elements in gamma Equ relative to the Sun.