CAOSP abstracts, Volume: 30, No.: 1, year: 2000

Abstract: We present projected rotational velocities distribution in He-rich stars against normal B type stars as well as the abundance analysis of light elements and their comparison with results of earlier series. The analysis is based on high-resolution observations (R=40000) collected at ESO, La Silla, Chile in the optical region and includes 11 stars, amongst them 5 new stars in comparison with an earlier sample. The distribution of projected rotational velocities shows a significant excess of slow rotators, no He-rich stars having v sin i > 130 km/s at the significance level of 99.5%. Based on fully consistent LTE models, the helium abundance ranges from 0.1 (solar) to 0.4. The analysis on the new sample confirms the results of earlier paper: the light element abundances display a diverse pattern from under-solar up to above-solar values. Carbon has the same abundance in He-rich and in standard stars for cool He-rich stars, following the predictions of radiative diffusion in the presence of wind. The star HD149363 appears rather as He-weak as based on the equivalent widths from R=40 000 spectra.

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