On the correlation between helium abundance in the atmospheres of early B-stars and their age and mass

For early B-stars with accurately determined helium abundance εHe the mass M and the age t were evaluated. It has been shown that if the stars are grouped on masses, there exists a correlation between εHe and t in each group. In addition, the rate εHe of helium enrichment in stellar atmospheres increases with M. The value of εHe depends linearly on M in the interval M/Msun=6-14. For the stars with such masses the helium abundance in atmospheres increases by 0.03-0.05 for the time of hydrogen burning in the core, whereas for the stars with M≤5Msun the εHe raising does not exceed 0.01. The εHe dependence on M and t with analogous dependence found for nitrogen may have an evolutionary nature and may shown that in the main sequence stage a mechanism already exists which leads to the transfer of CNO cycle-products from stellar interiors to the surface