An astrometric and spectroscopic study of the ? Scuti variable HD 21190 and its wide companion CPD-83A°A 64B

Although pulsations of delta Scuti type are not expected among Ap stars from a theoretical point of view, previous observations of the known delta Scuti star HD 21190 indicated a spectral classification F2 III SrEuSi:, making it the most evolved Ap star known. Our atmospheric chemical analysis based on recent High Accuracy Radial velocity Planet Searcher observations confirms the presence of chemical peculiarities in HD 21190. This star is also the only target known to host a magnetic field along with its delta Scuti pulsation properties. Using an astrometric analysis, we show that HD 21190 forms a physical binary system with the companion CPD -83A degrees A 64B. The presented astrometric and spectroscopic study of the binary components is important to understand the complex interplay between stellar pulsations, magnetic fields and chemical composition.