| Abstract
| - The small-amplitude Cepheid SU Cas and four members of the association Cas OB2 ( HD 16893, HD 17327a and b, HD 17443) were investigated, using high-resolution CCD spectra. The following results were obtained: 1) All these objects have the same metallicity values, close to that of the Sun; 2) Elemental abundance indicates that SU Cas is a post first dredge-up star with an age from 1 10 8 to 1.45 10 8 yr, and it is not crossing the Cepheid instability strip for the first time. The mean value of $\log g$ = 2.35 corresponds to pulsations in the fundamental tone, although errors in gravity estimations provide overtone pulsations. The questions about its pulsational mode and membership in Cas OB2 remained open; 3) HD 17327a is a slowly rotating HgMn-star with the highest helium content among such objects, while HD 16893 also has a manganese overabundance and might be classified as an Am-star; 4) HD 17327b and HD 17443 are rapidly rotating main-sequence stars, while HD 17443 has a helium content comparable with that of the Sun.
|
