Spectrum of the Delta Scuti variable 20 Canum Venaticorum

We have analyzed the high dispersion spectra of 20 CVn by using model atmospheres. By fitting computed continua, hydrogen lines, ionization equilibria etc. to the observed quantities, we derive a reciprocal effective temperature theta(eff.) = 0.64+-0.02, a surface gravity log g=3.8+-0.3, and a microturbulent velocity xi=(3.5+-0.5) kms-1 (depth-independent). The abundances of 26 elements relative to the Sun are determined. C, N and O are normal. The elements Al, Si, S, Ca, Sc, Cr, Mn, Fe, Ni, Y, and La are overabundant by a factor of 2 to 4, and Na, Mg, Ti, V, Co, Cu, and Zn by a factor of about 5. Among the heavy elements, Sr, Zr, Ba, and Ce are overabundant by a factor of 7 to 10, while Eu is overabundant by a factor of 16. The abundances of the chemical elements relative to Fe in delta Scuti stars are compared with those in Am stars. The general abundance pattern of delta Scuti stars suggests that in delta Scuti stars Am anomalies are less pronounced (often becoming normal) than in Am stars. The results can be explained by the diffusion hypothesis. (author)