Hydrodynamic Model of Decaying Radial Oscillations in RU Cam

نویسندگان

چکیده

Calculations of stellar evolution up to the early white dwarf stage were carried out for stars with mass on main sequence $M_0=0.82M_\odot$, $0.85M_\odot$, $0.9M_\odot$ and initial abundances helium heavier elements $Y=0.25$ $Z=10^{-3}$, respectively. For each value $M_0$ AGB post--AGB evolutionary phases computed three values loss parameter in Bl\"ocker formula: $\eta_B=0.02$, 0.05 0.1. The variable star RU~Cam pulsation period $\Pi\approx 22$ day is shown be amplitude decrease years 1962--1963 due movement across HR diagram beyond instability region. Theoretical estimates luminosity are $0.524M_\odot\le M\le 0.532M_\odot$ $2.20\times 10^3L_\odot\le L\le 2.33\times 10^3L_\odot$, Hydrodynamic calculations nonlinear pulsations show that while approaches boundary a significant reduction ($\approx 90\%$) occurs nearly two subsequent slow decay low--amplitude oscillations. Solution equations hydrodynamics time--dependent inner conditions describing changes radius at bottom pulsating envelope allows us conclude radial oscillations accompanied by effect oscillation hysteresis. In particular, large--amplitude limit cycle extends $\approx 12$ decaying small--amplitude oscilations spreads formal instability.

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ژورنال

عنوان ژورنال: Astronomy Letters

سال: 2021

ISSN: ['1063-7737', '1562-6873']

DOI: https://doi.org/10.1134/s1063773721110025