Hostname: page-component-78c5997874-t5tsf Total loading time: 0 Render date: 2024-11-18T18:47:47.489Z Has data issue: false hasContentIssue false
  • English
  • Français

The role of convective boundaries

Published online by Cambridge University Press:  25 May 2016

F. Herwig ,
T. Blöcker  and
D. Schönberner
F. Herwig
Affiliation:
Institut für Physik, Universität Potsdam, Germany
T. Blöcker
Affiliation:
Max-Planck-Institut für Radioastronomie, Bonn, Germany
D. Schönberner
Affiliation:
Astrophysikalisches Institut Potsdam, Germany

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

We investigate the influence of convective overshoot on stellar evolution models of the thermal pulse AGB phase with MZAMS = 3M⊙. 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 13C-pocket can form after the third dredge-up event which may be crucial for n-capture nucleosynthesis.

Type
Part 1. Basic Facts, Structure, Evolution, Nucleosynthesis
Information
Symposium - International Astronomical Union , Volume 191: Asymptotic Giant Branch Stars , 1999 , pp. 41 - 46
Copyright
Copyright © Astronomical Society of the Pacific 1999 

References

Alongi, M., Bertelli, G., Bressan, A., Chiosi, C., 1991, A&A 244, 95 Google Scholar
Freytag, B., Ludwig, H.-G., Steffen, M., 1996, A&A 313, 497 Google Scholar
Gallino, R., Arlandini, C., Busso, M., Lugaro, M., Travaglio, C., Straniero, O.A., Limongi, M., 1998, ApJ 497, 388 Google Scholar
Groenewegen, M., van den Hoek, L., de Jong, T., 1995, A&A 293, 381 Google Scholar
Herwig, F., Blöcker, T., Schönberner, D., El Eid, M.F., 1997, A&A 324, L81 Google Scholar
Herwig, F., Schönberner, D., Blöcker, T., 1998, A&A 340, L43 Google Scholar
Iben, I. Jr., 1976, ApJ 208, 165 Google Scholar
Iben, I. Jr., McDonald, J., 1995, in White Dwarfs, Koester, D. and Werner, K. (eds.), No. 443 in LNP, Springer, Heidelberg, p. 48 Google Scholar
Maeder, A., 1975, A&A 40, 303 Google Scholar
Marigo, P., Bressan, A., Chiosi, C., 1996, A&A 313, 545 Google Scholar
Paczyński, B., 1970, Acta Astr. 20, 47 Google Scholar
Schaller, G., Schaerer, D., Meynet, G., Maeder, A., 1992, A&AS 96, 269 Google Scholar
Shaviv, G., Salpeter, E., 1973, ApJ 184, 191 CrossRefGoogle Scholar
Straniero, O., Chieffi, A., Limongi, M., Busso, M., Gallino, R., Arlandini, C., 1997, ApJ 478, 332 Google Scholar
Werner, K., Dreizler, S., Rauch, T., Koesterke, L., Heber, U., 1998, this volume Google Scholar