Resumen

GARBA, L.  y  AHMED, F. A.. Nuclear adiabatic effects of electron-positron pairs on the dynamical instability of very-massive stars. Rev. mex. fis. [online]. 2022, vol.68, n.1.  Epub 23-Jun-2023. ISSN 0035-001X.  https://doi.org/10.31349/revmexfis.68.011403.

The adiabatic effects of electron-positron pair-production on the dynamical instability of very-massive stars is investigated from stellar progenitors of carbon-oxygen cores within the range of $64M_{\odot }<M_{CO}<133M_{\odot }$ both with and without rotation. At a very high temperature and relatively low density, the production of electron-positron pairs in the centres of massive stars leads the adiabatic index below 4/3. The adiabatic quantities are evaluated by constructing a model into a thermodynamically consistent electron-positron equation of state (EoS) table. It is observed that the adiabatic indices in the instability regions of the rotating models are fundamentally positive with central temperature and density. Similarly, the mass of the oxygen core within the instability region accelerates the adiabatic indices in order to compress the star, while the mass loss and adiabatic index in the non-rotating model exponentially decay. In the rotating models, a small amount of heat is required to increase the central temperature for the end fate of the massive stars. The dynamics of most of the adiabatic quantities shosw a similar pattern for all the rotating models. The non-rotating model may not be suitable for inducing instability. Many adiabatic quantities have shown great effects on the dynamical instability of the massive stars due to electron-positron pair-production in their centres. The results in this work would be useful for better understanding of the end fate of very-massive stars.

Palabras llave : Massive stars; pair-production; stellar instability.

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