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arXiv · 1806.06836

Evolution and period change in RR Lyr variables of the globular cluster M 3

Yu. A. Fadeyev
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Abstract

The grid of evolutionary tracks of population II stars with initial masses from $0.81M_\odot$ to $0.85M_\odot$ and chemical composition of the globular cluster M 3 is computed. Selected models of horizontal branch stars were used as initial conditions for solution of the equations of radiation hydrodynamics and time--dependent convection describing radial stellar oscillations. The boundaries of the instability strip on the Herztsprung--Russel diagram were determined using nearly 100 hydrodynamic models of RR Lyr pulsating variables. For each evolutionary track crossing the instability strip the pulsation period was determined as a function of evolutionary time. The rate of period change of most variables is shown to range within $-0.02\le\dotΠ\le 0.05~\mathrm{day}/10^6\mathrm{yr}$. Theoretical estimate of the mean period change rate obtained by the population synthesis method is $\langle\dotΠ\rangle=6.0\times 10^{-3}~\mathrm{day}/10^6\mathrm{yr}$ and agrees well with observations of RR Lyr variables of the globular cluster M 3.

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Yu. A. Fadeyev. 2018-06-18. Evolution and period change in RR Lyr variables of the globular cluster M 3. https://doi.org/10.1134/s1063773718100018

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