^1,6,7Hung Kwan Fok,^2,3,4,7Marco Pignatari,^2,7Benoît Côté,^5,1,7Reto Trappitsch
The Astrophysical Journal Letters 977, L24 Open Access Link to Article [DOI 10.3847/2041-8213/ad91ab]
¹Department of Physics, Brandeis University, Abelson-Bass-Yalem 107, Waltham, MA 02453, USA
²Konkoly Observatory, Research Centre for Astronomy and Earth Sciences, HUN-REN, Konkoly Thege M. út 15-17, Budapest 1121, Hungary
³ CSFK, MTA Centre of Excellence, Konkoly Thege Miklós út 15-17, Budapest 1121, Hungary
⁴E. A. milne Centre for Astrophysics, University of Hull, Cottingham Road, Kingston upon Hull, HU6 7RX, UK
⁵Laboratory for Biological Geochemistry, School of Architecture, Civil & Environmental Engineering, École
Polytechnique Fédérale de Lausanne, GR C2 505, Station 2, 1015 Lausanne, Switzerland
⁶Morton K. Blaustein Department of Earth & Planetary Sciences, Johns Hopkins University, Olin Hall, 3300 San Martin Drive, Baltimore, MD 21218, USA
⁷NuGrid Collaboration (https://nugridstars.org)

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 represent the pristine stellar composition. Silicon isotopes can thus be used as a proxy for galactic chemical evolution (GCE). However, the measured correlation of ²⁹Si/²⁸Si versus ³⁰Si/²⁸Si 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 GCE 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.