Revisiting the stability of strange-dwarf stars and strange planets

TL;DR

This paper investigates the stability of strange-dwarf stars and planets with quark-matter cores and nuclear crusts, revealing that rapid conversion processes destabilize these objects, while slow conversions allow for a stable configuration.

Contribution

It provides a detailed analysis of the dynamical stability of strange-dwarf objects considering different conversion rates and equations of state, extending previous stability results.

Findings

Rapid conversions lead to complex eigenfrequencies, destabilizing strange dwarfs and planets.

Slow conversions allow for a significant stability window consistent with earlier studies.

Results are robust across different transition densities and equations of state.

Abstract

The dynamical stability of strange-dwarf hybrid stars and strange planets, constituted by strange-quark-matter cores and dilute-nuclear-matter crusts, is revisited by analyzing the fundamental mode eigenfrequencies of the radial oscillation equations with boundary conditions for slow (rapid) conversions originating at the density-discontinuous interface characterizing extremely large (small) microscopic timescales compared to the oscillation periods. For the hadronic crust we used an analytic fit of the BPS results matched to the massless MIT bag model. For the rapid case, our calculations indicate that the zero mode is the so-called {\it reaction mode} whose frequency is a complex number, thus ruling out the existence of strange dwarfs (planets) in nature. On the other hand, slow conversions still provide a sizeable stability window which, interestingly, also reproduces the Glendenning-Kettner-Weber results. The robustness of our findings is demonstrated for different transition densities and using an equation of state from perturbative QCD for the ultra-dense core.