Segregation of Calcium Isotopes in the Atmospheres of CP Stars as a Consequence of Light-Induced Drift

摘要: A mechanism for the segregation of calcium isotopes in atmospheres chemically peculiar (CP) stars due to light-induced drift (LID) singly charged 48Ca+ ions is discussed. One peculiarity Ca+ that an adequate description effect LID requires taking into account several energy levels Ca+, and thus pairs relative differences (ν i − ν k )/ν transport frequencies collisions i k with neutral atoms (hydrogen, helium). The known real (calculated ab initio) interaction potentials are used numerically calculate factors states H He atoms. These computations show that, at temperatures characteristic CP stars, T = 6600−12 000 K, fairly high values obtained ions, ≈ 0.4−0.6. Simple, transparent demonstrate rates cool (Teff 6600 K) exceed rate light pressure by two orders magnitude. directed upward stellar atmosphere, heavy isotope 48Ca pushed upper layers atmosphere. This can explain observed predominance atmospheric stars; according radiative-diffusion theory, action alone (in absence LID) would lead sinking deeper following lighter main 40Ca. LIDrate decreases its increases growth effective stars. manifestations roughly comparable near Teff 9500 K.