A search for rapid pulsations in the magnetic cool chemically peculiar star HD3980

The Ap star HD3980 appears to be a promising roAp candidate based on its fundamental parameters, leading us to search for rapid pulsations with the VLT UV-Visual Echelle Spectrograph (UVES). A precise Hipparcos parallax and estimated temperature of 8100K place HD3980 in the middle of the theoretical instability strip for rapidly oscillating Ap stars, about halfway through its main-sequence evolution stage. The star has a strong, variable magnetic field, as is typical of the cool magnetic Ap stars. Dipole model parameters were determined from VLT observations using Focal Reducer and low Dispersion Spectrograph (FORS)1. From Doppler shift measurements for individual spectral lines of rare-earth elements and the Halpha line core, we find no pulsations above 20-30ms-1. This result is corroborated by the inspection of lines of several other chemical elements, as well as with cross-correlation for long spectral regions with the average spectrum as a template. Abundances of chemical elements were determined and show larger than solar abundances of rare-earth elements. Further, ionization disequilibria for the first two ionized states of Nd and Pr are detected. We also find that the star has a strong overabundance of manganese, which is typical for much hotter HgMn and other Bp stars. Line profile variability with the rotation period was detected for the majority of chemical species.