Astron. Astrophys. 334, 505-539 (1998)

Galactic chemical enrichment with new metallicity dependent stellar yields

L. Portinari ¹, C. Chiosi ^{1, 2} and A. Bressan <sup>3

1</sup> Department of Astronomy, University of Padova, Vicolo dell'Osservatorio 5, I-35122 Padova, Italy (portinari, chiosi, bressan@pd.astro.it)
² European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748, Garching bei München, Germany
³ Astronomical Observatory of Padova, Vicolo dell'Osservatorio 5, I-35122 Padova, Italy

Received 2 December 1997 / Accepted 11 February 1998

Abstract

New detailed stellar yields of several elemental species are derived for massive stars in a wide range of masses (from 6 to 120  ) and metallicities ( 0.0004, 0.004, 0.008, 0.02, 0.05). Our calculations are based on the Padova evolutionary tracks and take into account recent results on stellar evolution, such as overshooting and quiescent mass-loss, paying major attention to the effects of the initial chemical composition of the star. We finally include modern results on explosive nucleosynthesis in SNæ by Woosley & Weaver (1995). The issue of the chemical yields of Very Massive Objects (from 120 to 1000  ) is also addressed.

Our grid of stellar yields for massive stars is complementary to the results by Marigo et al. (1996, 1998) on the evolution and nucleosynthesis of low and intermediate mass stars, also based on the Padova evolutionary tracks. Altogether, they represent a complete set of stellar yields of unprecedented homogeneity and self-consistency.

Our new stellar yields are inserted in a code for the chemical evolution of the Galactic disc with infall of primordial gas, according to the formulation first suggested by Talbot & Arnett (1971, 1973, 1975) and Chiosi (1980). As a first application, the code is used to develop a model of the chemical evolution of the Solar Vicinity, with a detailed comparison to the available observational constraints.

Key words: nuclear reactions, nucleosynthesis, abundances stars: mass loss supernovae: general Galaxy: evolution Galaxy: abundances solar neighbourhood

Send offprint requests to: L. Portinari

Contents

• 1. Introduction
• 2. Definition of the mass intervals
• 3. Ejecta from the stellar wind of massive stars
• 4. The supernova explosion
  • 4.1. The adopted and relations
  • 4.2. Electron capture supernovæ
  • 4.3. Iron-core collapse supernovæ
  • 4.4. Pair creation supernovæ
• 5. The total ejecta of massive stars
• 6. Low and intermediate mass stars
• 7. Very massive objects
• 8. The chemical evolution model
  • 8.1. The infall term
  • 8.2. The star formation rate
  • 8.3. The initial mass function
  • 8.4. The contribution of stellar ejecta
  • 8.5. Stellar lifetimes
  • 8.6. The numerical solution
  • 8.7. Inserting type Ia supernovæ
• 9. Chemical evolution in the Solar Neighbourhood
  • 9.1. The current infall rate
  • 9.2. The current gas fraction
  • 9.3. The supernova rates
  • 9.4. The age-metallicity relation
  • 9.5. The star formation rate
  • 9.6. The G-dwarf distribution
  • 9.7. Abundance ratios
• 10. Summary and conclusions
• Acknowledgements
• Appendix
  • Appendix A: the link with SN models
  • Appendix B: Some warnings about the link
  • Appendix C: Calculating the Q_ij matrix
• References

© European Southern Observatory (ESO) 1998

Online publication: May 15, 1998

helpdesk.link@springer.de