2023/12/13 by Yu. A. Fadeyev, Fadeyev, Yu. A.
Physics and Astronomy · #Astronomy and Astrophysical Research #FOS: Physical sciences #Solar and Space Plasma Dynamics #Solar and Stellar Astrophysics (astro-ph.SR) #Stellar, planetary, and galactic studies
paper · pdf · doi:10.48550/arxiv.2312.07973
openalex publication_date 2023/12/13 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Evolutionary sequences of AGB stars with initial masses on the main sequence MZAMS=1.5M_\odot, 2M_\odot and 3M_\odot were computed for the initial metallicity Z=0.014. Selected models of evolutionary sequences with envelopes under thermal equilibrium were used as initial conditions for calculation of nonlinear stellar pulsations. The hydrodynamic models of each evolutionary sequence are shown to concentrate along the continuous line in the period-radius and period-luminosity diagrams. The theoretical period-radius and period-luminosity relations differ from one another for different main-sequence star masses because the stellar luminosity of AGB stars depends on the degenerate carbon core mass which increases with increasing MZAMS. In hydrodynamic models of evolutionary sequences MZAMS=2M_\odot and MZAMS=3M_\odot the periods of the first overtone pulsators are 86~\textrmd≤Π≤ 123~\textrmd and 174~\textrmd≤Π≤ 204~\textrmd, whereas all models of the evolutionary sequence MZAMS=1.5M_\odot oscillate in the fundamental mode. Fairly regular radial oscillations exist in stars with pulsation periods Π\lesssim 500 d. In models with longer periods the amplitude rapidly increases with increasing Π and oscillations become irregular.