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VeSElkA: Vertical Stratification of Element Abundances in CP stars

A portion of the upper main-sequence stars, called chemically peculiar (CP) stars, show significant abundance anomalies mainly due to atomic diffusion of chemical elements within the stellar atmospheres of these stars. Slowly rotating CP stars may have hydrodynamically stable atmospheres where the competition between the gravitational and radiative forces leads to atomic diffusion that can be responsible for the abundance peculiarities observed in CP stars. Recently, project VeSElkA (Vertical Stratification of Element Abundances) was initiated with the aim to detect and study the vertical stratification of element abundances in the atmospheres of CP stars. Some results from abundance analysis of several slowly rotating (V$\sin{i}$< 40 km/s) CP stars observed recently with ESPaDOnS are presented here. Signatures of vertical abundance stratification for several chemical elements have been found in the stellar atmospheres of HD~22920, HD~41076, HD~95608, HD~116235, HD~148330 and HD~157087.