Initial helium abundance and period distribution of RR Lyr type variables in the globular cluster M3
Abstract
Evolutionary calculations for stars with masses on the main sequence 0.812M ⊙ ≤ M 0 ≤ 0.83M⊙ and initial helium abundances 0.245 ≤ Y 0 ≤ 0.255 were carried out up to core helium exhaustion. The abundance of heavy elements Z 0 = 10^-3 corresponds to the chemical composition of the globular cluster M3. The mass loss rate was evaluated by the Reimers formula with parameter η R = 0.56. Selected models of evolutionary sequences were used as initial conditions for solution of the equations of hydrodynamics and time-dependent convection describing radial stellar oscillations on the core helium burning stage. For each crossing of the instability strip we determined the pulsation period as a function of evolutionary time. The fraction of fundamental mode pulsators f 0 was evaluated using Monte-Carlo simulations. It increases with decreasing both Y 0 and M 0, but does not exceed ≈ 50% for considered ranges of Y 0 and M 0 .
- Publication:
-
INASAN Science Reports
- Pub Date:
- October 2019
- DOI:
- 10.26087/INASAN.2019.3.1.024
- Bibcode:
- 2019INASR...3..156F