On the Sensitivity of Massive Star Nucleosynthesis and Evolution to Solar Abundances and to Uncertainties in Helium Burning Reaction Rates

TL;DR

This study examines how uncertainties in helium burning reaction rates and updated solar abundances influence massive star evolution and supernova nucleosynthesis, highlighting the need for precise reaction rate measurements.

Contribution

It demonstrates the impact of revised solar abundances and reaction rate uncertainties on supernova yields and stellar evolution predictions.

Findings

Supernova yields align with solar ratios within current reaction rate uncertainties.

Variations in reaction rates significantly affect core carbon abundance and remnant mass.

Accurate helium burning rates are crucial for reliable stellar evolution models.

Abstract

We explore the dependence of pre-supernova evolution and supernova nucleosynthesis yields on the uncertainties in helium burning reaction rates. Using the revised solar abundances of Lodders (2003) for the initial stellar composition, instead of those of Anders & Grevesse (1989), changes the supernova yields and limits the constraints that those yields place on the 12C(a,g)16O reaction rate. The production factors of medium-weight elements (A = 16-40) were found to be in reasonable agreement with observed solar ratios within the current experimental uncertainties in the triple alpha reaction rate. Simultaneous variations by the same amount in both reaction rates or in either of them separately, however, can induce significant changes in the central 12C abundance at core carbon ignition and in the mass of the supernova remnant. It therefore remains important to have experimental determinations of the helium burning rates so that their ratio and absolute values are known with an accuracy of 10% or better.