STELLAR INVESTIGATION IN THE OPEN CLUSTER OF POLARIS

We present the results of our analysis of high-resolution spectroscopic observations of Cepheid α UMi (Polaris A), and main-sequence type stars Polaris B, and HD 5914, an optical companion and a member of Polaris open cluster. The last ones are objects with high projected rotational velocities v sin i = 110 km s-1 and 100 km -1, respectively. The derived atmosphere parameters are: Polaris A: Teff=6020 K; log g=2.2; Vt=4.2 km s-1; Polaris B: Teff=6900 K; log g=4.3; Vt=2.5 km s-1; HD 5914: Teff=8800 K; log g=4.0; Vt=2.0 km s-1. C, Na and Mg content in last two stars is close to solar, whereas for Polaris A these values are typical for Cepheid after the first dredge-up stage. The distances to Polaris B and HD 5914 are 109.5 and 108 pc, respectively. The RV pulsational amplitude of Polaris A increased to 7.5 km s-1 in 2003, decreased to 0.6 km s-1 in 2005 and increased anew to 2.5 s-1 in 2007