Spectroscopic study of the Ap star 73 Draconis

An analysis of spectrograms of the Ap star 73 Draconis is made to study the variations of line intensities and elemental abundances. Intensity variations of 15 elements are obtained and they are classified into three groups. Abundances of 22 elements are determined by a fine analysis technique at two phases (at Eu II maximum and minimum). Model parameters are determined from the ionization equilibrium, H gamma profile, and from photometric data. The state of ionization is found to be essentially unchanged between these two phases. Also, no periodic variation in the H gamma profile can be detected. The effective temperature T sub(eff)=8900K and the surface gravity log sub(g)=3.9 are adopted at both phases. The abundances of Al, Ca, and Sc are found to be deficient at both phases by a factor of 3 to 40 compared to the solar abundances. Mg, Si, V, Fe, Y, and Ba are normal. Cr, Mn, Co, Ni, Sr, Zr, and rare earth elements are over-abundant by a factor of 3 to 1000. Ti is nearly normal at Eu II minimum, while it is overabundant by a factor of 10 at Eu II maximum. Mg, Ca, Ti, Mn, Sr, and Eu show apparent changes in their abundances by a factor of 2 or more between the two phases and ''abundance spots'' of these elements are discussed. (auth.)