Astron. Astrophys. 327, 349-360 (1997)

Updated solar models

P. Morel , J. Provost and G. Berthomieu

Département Cassini, UMR CNRS 6529, Observatoire de la Côte d'Azur, BP 4229, F-06304 Nice Cedex 4, France

Received 21 March 1997 / Accepted 26 May 1997

Abstract

Solar models computed with mass loss, microscopic diffusion of helium and heavy element, and with updated physics have been evolved from the pre-main sequence to present day; they are compared to the observational constraints including lithium depletion and to the seismic reference model of Basu et al. (1996), derived by inversion. Microscopic diffusion significantly improves the agreement with the observed solar frequencies and agree with the seismic reference model within for the sound velocity and for the density, but slightly worsens the neutrino problem. Neither microscopic diffusion nor overshooting explain the observed lithium depletion consistently with helioseismological constraints, while a mass loss process does it. Models computed with OPAL equation of state and opacities are in a better agreement with the seismic sound speed. To reach the level of precision of helioseismological observations the accuracy of solar models still needs to be improved by one order of magnitude; any such improvement will necessitate equation of state and opacity data taking into account of detailed changes in the mixture.

Key words: Sun: abundances Sun: evolution Sun: oscillations Sun: interior

Send offprint requests to: P. Morel, morel@obs-nice.fr

Contents

• 1. Introduction
• 2. Observational constraints and calibration of solar models
• 3. Physics of solar models
  • 3.1. Initial conditions and nuclear network
  • 3.2. The opacities and equation of state
  • 3.3. Diffusion
  • 3.4. Convection, overshooting and undershooting
  • 3.5. Lithium depletion and mass loss
• 4. Computation of models and frequencies
  • 4.1. Solar models
  • 4.2. p-Mode oscillation calculations
• 5. Results and discussion
  • 5.1. The solar models without microscopic diffusion
  • 5.2. Standard solar models with microscopic diffusion
    • 5.2.1. Sensitivity to equation of state and
    • 5.2.2. Sensitivity to age and
    • 5.2.3. depletion due to undershoot and mass loss
    • 5.2.4. Overshoot of the convective core of the young Sun
• 6. Conclusions
• Acknowledgements
• Appendix
  • Appendix A: calculation of abundances
  • Appendix B: ³ He abundance, equation of state and opacities
• References

© European Southern Observatory (ESO) 1997

Online publication: April 8, 1998
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