Presupernova evolution and explosive nucleosynthesis of rotating massive stars II: the Super Solar models at [Fe/H]=0.3

TL;DR

This study extends models of rotating massive stars at super-solar metallicity, revealing how increased mass loss influences core properties and nucleosynthesis yields, especially highlighting primary neutron capture element production in rotating stars.

Contribution

It introduces models of rotating massive stars at [Fe/H]=0.3, demonstrating the impact of higher metallicity and mass loss on stellar evolution and nucleosynthesis, with novel insights into primary neutron capture processes.

Findings

Higher metallicity leads to smaller He- and CO-core masses at collapse.

Rotating models show increased primary neutron capture element yields.

Non-rotating models exhibit expected secondary nucleosynthesis trends.

Abstract

We present an extension of the set of models published in Limongi & Chieffi, 2018, ApJS, 237, 13, at metallicity two times solar, i.e. [Fe/H]=0.3. The key physical properties of these models at the onset of the core collapse are mainly due to the higher mass loss triggered by the higher metallicity: the super solar metallicity (SSM) models reach the core collapse with smaller He- and CO-core masses, while the amount of 12C left by the central He burning is higher. These results are valid for all the rotation velocities. The yields of the neutron capture nuclei expressed per unit mass of Oxygen (i.e. the X/O) are higher in the SSM models than in the SM ones in the non rotating case while the opposite occurs in the rotating models. The trend shown by the non rotating models is the expected one, given the secondary nature of the n-capture nucleosynthesis. Vice versa, the counter intuitive trend obtained in the rotating models is the consequence of the higher mass loss present in the SSM models that removes the H rich envelope faster than in the SM ones while the stars are still in central He burning, dumping out the entanglement (activated by the rotation instabilities) and therefore a conspicuous primary n-capture nucleosynthesis.