Hydrodynamic modelling of pulsation period decrease in the Mira-type variable T UMi

Fadeyev, Yuri A.

doi:10.1093/mnras/stac1711

Cited by 8 publications

(4 citation statements)

References 17 publications

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“…Results of pulsation calculations are presented in the lower To obtain these dependencies we solved the initial-value problem for equations of hydrodynamics with the inner boundary conditions determined from evolutionary models. The method of calculations is described in Fadeyev (2022).…”

Section: Evolutionary Sequences For R Hyamentioning

confidence: 99%

“…A helium-shell flash is accompanied by two consecutive phases of declining stellar radius and luminosity (Wood & Zarro 1981;Iben 1982;Boothroyd & Sackmann 1988). The onset of the first stage nearly coincides with the maximum peak of the helium-shell luminosity L3α when the hydrogen-burning shell rapidly extinguishes (Fadeyev 2022). The stellar contraction ceases as soon as the radiation-diffusion wave from the helium-shell flash propagates up to the outer convection zone.…”

Section: Introductionmentioning

confidence: 99%

“…To this end we compute the non-linear stellar pulsations using the time-dependent inner boundary conditions determined from the evolutionary calculations. This method has been earlier employed for modelling the pulsation period decrease in the Mira-type variable T UMi (Fadeyev 2022).…”

Section: Introductionmentioning

confidence: 99%

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Evolutionary and Hydrodynamic Models of Short-Period Cepheids

Fadeyev

2020

Astron. Lett.

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Pulsation period evolution during the helium-shell flash in the Mira variable R Hya is investigated using consistent stellar evolution and non-linear stellar pulsation computations. The initial and time-dependent inner boundary conditions for the equations of radiation hydrodynamics describing non-linear stellar oscillations were determined using a grid of TP-AGB model sequences with initial masses on the main sequence 1.5M ⊙ ≤ M ZAMS ≤ 5.0M ⊙ and the initial metallicity Z = 0.014. The setup of initial conditions for hydrodynamic models corresponds to ≈ 100 yr prior to the maximum of the helium-shell luminosity and ensures that the stellar envelope of the evolution model is under both hydrostatic and thermal equilibrium. Solution of the equations of hydrodynamics allowed us to determine the temporal variation of the pulsation period Π(t) during ≈ 500 yr. Within this time interval R Hya is a fundamental mode pulsator. The period temporal dependencies Π(t) calculated for the AGB star models at the beginning of the third dredge-up phase and with masses 4.4M ⊙ < ≈ M < ≈ 4.5M ⊙ are in agreement with observational estimates of the period of R Hya obtained during last two centuries. The mean radius of R Hya pulsation models at the end of the XX century (470R ⊙ < ≈ R < ≈ 490R ⊙ ) agrees with observational estimates obtained using the interferometric angular diameter measurements.

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Section: Evolutionary Sequences For R Hyamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Evolutionary and Hydrodynamic Models of Short-Period Cepheids

Fadeyev

2020

Astron. Lett.

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“…In regions where the opacity increases with temperature (e.g., where hydrogen and helium are partly ionized), the atmosphere becomes unstable against pulsations (Hansen et al 2004;Kippenhahn et al 2012;Das et al 2020;Kurtz 2022). Hydrogen ionization drives the pulsations of Mira variables (Fox & Wood 1982;Fadeyev 2022) and red supergiants (Heger et al 1997;Yoon & Cantiello 2010), the high-overtone, low-degree, nonradial pressure modes of rapidly oscillating Ap stars (Kurtz 1982;Shibahashi & Takata 1993;Bigot & Dziembowski 2002;Holdsworth et al 2021), and ZZ Ceti variables (Landolt 1968;Córsico et al 2019). Helium ionization drives pulsations in RR Lyrae variables (Smith 2004;Ngeow et al 2022) and δ Scuti variables (Balona 2018;Bowman & Kurtz 2018;Guzik 2021;Murphy et al 2023), DBV white dwarf variables (Córsico et al 2019;Saumon et al 2022), and is furthermore responsible for acoustic glitches in solar-like oscillators (Gough 1990;Mazumdar et al 2014;Verma et al 2017Verma et al , 2019Saunders et al 2023).…”

Section: Introductionmentioning

confidence: 99%

An Expanded Set of Los Alamos OPLIB Tables in MESA: Type-1 Rosseland-mean Opacities and Solar Models

Farag,

Fontes,

Timmes

et al. 2024

ApJ

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We present a set of 1194 Type-1 Rosseland-mean opacity tables for four different metallicity mixtures. These new Los Alamos OPLIB atomic radiative opacity tables are an order of magnitude larger in number than any previous opacity table release, and span regimes where previous opacity tables have not existed. For example, the new set of opacity tables expands the metallicity range to Z = 10−6 to Z = 0.2, which allows improved accuracy of opacities at low and high metallicity, increases the table density in the metallicity range Z = 10−4 to Z = 0.1 to enhance the accuracy of opacities drawn from interpolations across neighboring metallicities, and adds entries for hydrogen mass fractions between X = 0 and X = 0.1 including X = 10−2, 10−3, 10−4, 10−5, 10−6 that can improve stellar models of hydrogen deficient stars. We implement these new OPLIB radiative opacity tables in MESA and find that calibrated solar models agree broadly with previously published helioseismic and solar neutrino results. We find differences between using the new 1194 OPLIB opacity tables and the 126 OPAL opacity tables range from ≈20% to 80% across individual chemical mixtures, up to ≈8% and ≈15% at the bottom and top of the solar convection zone respectively, and ≈7% in the solar core. We also find differences between standard solar models using different opacity table sources that are on par with altering the initial abundance mixture. We conclude that this new, open-access set of OPLIB opacity tables does not solve the solar modeling problem, and suggest the investigation of physical mechanisms other than the atomic radiative opacity.

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Hydrodynamic models of pulsation period evolution in R Hydrae

Fadeyev

2024

Monthly Notices of the Royal Astronomical Society

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Pulsation period evolution during the helium–shell flash in the Mira variable R Hya is investigated using consistent stellar evolution and non–linear stellar pulsation computations. The initial and time–dependent inner boundary conditions for the equations of radiation hydrodynamics describing non–linear stellar oscillations were determined using a grid of TP–AGB model sequences with initial masses on the main sequence 1.5M⊙ ≤ MZAMS ≤ 5.0M⊙ and the initial metallicity Z = 0.014. The setup of initial conditions for hydrodynamic models corresponds to ≈100 yr prior to the maximum of the helium–shell luminosity and ensures that the stellar envelope of the evolution model is under both hydrostatic and thermal equilibrium. Solution of the equations of hydrodynamics allowed us to determine the temporal variation of the pulsation period Π(t) during ≈500 yr. Within this time interval R Hya is a fundamental mode pulsator. The period temporal dependencies Π(t) calculated for the AGB star models at the beginning of the third dredge–up phase and with masses $4.4M_{\odot }\lessapprox M\lessapprox 4.5M_{\odot }$ are in agreement with observational estimates of the period of R Hya obtained during last two centuries. The mean radius of R Hya pulsation models at the end of the XX century ($470 R_{\odot }\lessapprox \bar{R}\lessapprox 490 R_{\odot }$) agrees with observational estimates obtained using the interferometric angular diameter measurements.

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Hydrodynamic modelling of pulsation period decrease in the Mira-type variable T UMi

Cited by 8 publications

References 17 publications

Evolutionary and Hydrodynamic Models of Short-Period Cepheids

Evolutionary and Hydrodynamic Models of Short-Period Cepheids

An Expanded Set of Los Alamos OPLIB Tables in MESA: Type-1 Rosseland-mean Opacities and Solar Models

Hydrodynamic models of pulsation period evolution in R Hydrae

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