Constraints on the Galactic Chemical Evolution of 3He
Abstract
We examine the galactic chemical evolution (GCE) of 3He in one-zone and multi-zone models, with particular attention to the stellar yields and GCE parameters that can reproduce both the protosolar 3He abundance and recent gas-phase 3He/4He measurements in the Orion nebula. Published stellar models indicate negligible net 3He production by massive stars, while the predicted yields from asymptotic giant branch (AGB) stars are metallicity-dependent and span a range of 2.5 depending on the extra mixing processes incorporated in the stellar models. The dominant contribution to 3He production comes from 1-2\ M stars, making 3He evolution slow compared to other AGB elements and to Fe enrichment from Type Ia supernovae. We constrain our GCE models to reproduce the observed [O/H] in the interstellar medium, and our fiducial models adopt an empirically motivated IMF-averaged oxygen yield y O ≈ 1.2\ Z O, . Even with the lowest of the AGB 3He yields, based on stellar models with rotational and thermohaline mixing, our GCE models tend to overpredict the protosolar and Orion 3He abundances; they require a slow onset of star formation and low star formation efficiency to come close to the observed values. With a higher oxygen yield, calibration to observed [O/H] implies stronger outflows, making it easier to reproduce the observed 3He. Alternatively, the true 3He yield could be lower than that predicted by existing stellar models, suggesting that mixing in red giants is not yet fully captured. Future 3He measurements that probe higher metallicity environments could help distinguish these possibilities.
Turn this paper into a lesson
ArcXiv compiles a structured reading guide from this paper's metadata: plain-English importance, contributions, prerequisite concepts, which sections to read first, flashcards, and a quiz. Grounded in the abstract, never invented.