Silicon Isotopic Composition of Mainstream Presolar SiC Grains Revisited: The Impact of Nuclear Reaction Rate Uncertainties

Abstract

Presolar grains are stardust particles that condensed in the ejecta or in the outflows of dying stars and can today be extracted from meteorites. They recorded the nucleosynthetic fingerprint of their parent stars and thus serve as valuable probes of these astrophysical sites. The most common types of presolar silicon carbide grains (called mainstream SiC grains) condensed in the outflows of asymptotic giant branch stars. Their measured silicon isotopic abundances are not significantly influenced by nucleosynthesis within the parent star, but rather represents the pristine stellar composition. Silicon isotopes can thus be used as a proxy for galactic chemical evolution. However, the measured correlation of ${}^{29}$Si/${}^{28}$Si versus ${}^{30}$Si/${}^{28}$Si does not agree with any current chemical evolution model. Here, we use a Monte Carlo model to vary nuclear reaction rates within their theoretical or experimental uncertainties and process them through stellar nucleosynthesis and galactic chemical evolution models to study the variation of silicon isotope abundances based on these nuclear reaction rate uncertainties. We find that these uncertainties can indeed be responsible for the discrepancy between measurements and models and that the slope of the silicon isotope correlation line measured in mainstream SiC grains agrees with chemical evolution models within the nuclear reaction rate uncertainties. Our result highlights the importance of future precision reaction rate measurements for resolving the apparent data-model discrepancy.

References in corpus (7)

• Array Programming with NumPy
• Modules for Experiments in Stellar Astrophysics (MESA)
• Observational constraints on the origin of the elements. IV: The standard composition of the Sun
• Barium Isotopic Composition of Mainstream Silicon Carbides from Murchison: Constraints for s-Process Nucleosynthesis in AGB Stars
• s-Processing in AGB Stars Revisited. III. Neutron captures from MHD mixing at different metallicities and observational constraints
• Zero and extremely low metallicity rotating massive stars: evolution, explosion, and nucleosynthesis up to the heaviest nuclei
• Chemical Evolution of Fluorine in the Milky Way

Cited by in corpus (2)

• Nuclear astrophysics
• Type Iax supernovae as a source of iron-rich silicate dust