The role of convective boundaries

F. Herwig; T. Bloecker; D. Schoenberner

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arXiv · astro-ph/9811129

The role of convective boundaries

F. Herwig·T. Bloecker·D. Schoenberner

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Abstract

We investigate the influence of convective overshoot on stellar evolution models of the thermal pulse AGB phase with M_ZAMS = 3 Msol. An exponential diffusive overshoot algorithm is applied to all convective boundaries during all evolutionary stages. We demonstrate that overshooting at the bottom of the pulse-driven convective zone, which forms in the intershell during the He-shell flash, leads to more efficient third dredge-up. Some overshoot at the bottom of the convective envelope removes the He-H discontinuity, which would otherwise prohibit the occurrence of the third dredge-up for this stellar mass. However, no correlation between the amount of envelope overshoot and the efficiency of the third dredge-up has been found. Increasingly efficient third dredge-up eventually leads to a carbon star model. Due to the partial mixing efficiency in the overshoot region a C13-pocket can form after the third dredge-up event which may be crucial for n-capture nucleosynthesis.

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F. Herwig, T. Bloecker, D. Schoenberner. 1998-11-09. The role of convective boundaries. https://arxiv.org/abs/astro-ph/9811129

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