| Abstract: Every atom heavier than hydrogen in the Milky Way records stellar processing, but isotopic compositions preserve the most detailed memory of the Galaxy’s chemical history. While elemental abundances trace global evolution, isotopic ratios retain sensitivity to stellar masses, nucleosynthetic pathways, delay times, and interstellar mixing, enabling a more stringent reconstruction of Galactic Chemical Evolution (GCE). We present an isotopically resolved GCE model of the Milky Way that links stellar nucleosynthesis, Galactic-scale evolution, and meteoritic constraints within a unified framework.
The Milky Way is modelled as a multi-zone system undergoing time-dependent gas accretion, star formation, and feedback-driven enrichment, following the inside-out disk growth paradigm (Chiappini et al. 1997; Matteucci 2012).The model tracks the isotopic evolution of the first 32 elements (H–Ge) and lead (Pb), incorporating metallicity-dependent yields from massive stars, asymptotic giant branch stars, and Type Ia supernovae. This isotopic treatment separates overlapping nucleosynthetic sources, including iron-peak and neutron-capture processes, with particular emphasis on late-time s-process Pb production (Karakas & Lugaro 2016).
Model parameters are constrained using a Bayesian Markov Chain Monte Carlo framework calibrated against stellar abundances, radial gradients, age–metallicity relations, and the solar isotopic composition (Asplund et al. 2021). It reproduces observed elemental trends while providing predictive isotopic histories and radial gradients across the Galactic disk.
Beyond stellar observations, this isotopic GCE framework directly interfaces with meteoritic and pre-solar grain studies by predicting the time and location-dependent isotopic composition of the Galactic ISM. This enables pre-solar grains to be placed within a quantitative Galactic context, constraining their stellar origins and formation epochs (Zinner 2014). Such an integrated isotopic approach significantly advances GCE as a predictive tool, with broad applications ranging from Galactic archaeology to the origin of Solar System material. |
