C. Doom

Nucleosynthesis and evolution of massive stars with mass loss and overshooting

The evolution of mass-losing stars that have M(ZAMS)/solar-M in the 50-100 range is examined. The stellar models used in this study include: (1) mass loss formalism for O, Of, and W-R stars; (2) the Roxburgh criterion for the convective core; and (3) a nuclear reaction network of 28 nuclides from H to Si-30 for analysis of energy production and chemical evolution during the H- and He-burning phases. The internal evolution of stars with solar masses of 50, 60, 80, and 100 is described by observing time variations of the stellar and convective core masses, and central temperature and density fluctuation during the H- and He-burning phases; the evolution of the models in the Hertzsprung-Russell diagram is studied. The formation of the chemical abundances in the convective core and surface of the stars is investigated. The composition of the stellar ejecta of the W-R stars is discussed. The data reveal that the computed evolutionary tracks and core and surface abundances correlate well with the observational data. 93 references.

Structure and evolution of single and binary stars

Foreword. 1. Introduction to the Stars. 2. The Equations of Stellar Structure. 3. The Equation of State. 4. Nuclear Reaction Rates. 5. Nuclear Burning in Stellar Interiors. 6. Astrophysical Opacities. 7. Stellar Convection. 8. Numerical Techniques. 9. The Formation of Stars. 10. Stellar Evolution During the Successive Nuclear Burning Phases. 11. The Evolution of Low Mass Stars. 12. The Evolution of Intermediate Stars (2.3-6M). 13. The Evolution of Massive Stars. 14. Final Stages of Single Star Evolution. 15. The Evolution of Binary Stars: General Considerations. 16. The Evolution of Low and Intermediate Mass Binaries. 17. The Evolution of Massive Close Binaries. 18. Final Stages of Close Binary Evolution. 19. Structure and Evolutionary Models for Single and Binary Stars. Annex: Polytropes. References. General References. Literature per Chapter. Subject Index.

Absolute dimensions of unevolved O type close binaries

A method is presented to derive the absolute dimensions of early-type detached binaries by combining the observed parameters with results of evolutionary computations. The method is used to obtain the absolute dimensions of nine close binaries. We find that most systems have an initial masss ratio near 1.

The Equations of Stellar Structure

In the previous chapter, we have from observations that stars are immense spheres of gas, radiating energy into space. In this chapter, we will describe how such a sphere of gas can be modeled.

The Evolution of Low and Intermediate Mass Binary Systems

During phases of nuclear burning the radius of the star increases. If the star is a member of a close binary, this increase is limited by the presence of the companion. If a well determined critical value of the radius is exceeded mass transfer can occur from one component to the other, or mass can even leave the system, or may be stored in rings or disks. The computation of these mass transfer stages is only possible when certain approximations are accepted. Hydrodynamics and deviations from spherical symmetry (rotational and tidal effects) are generally not considered and the orbit is usually considered as circular. The rotation of the components is assumed to be synchronized with the orbital motion. The evolution of close binary systems depends on the masses of the components, the mass ratio and the orbital period.

Nuclear Burning in Stellar Interiors

The nuclear reactions in the stellar interior do not only produce the energy to make the star shine but also transform elements into others, like chemical reactions transform molecules into other molecules. As an example, we can consider the reaction

The Equation of State

{}^{12}{\rm{C}} + {}^{{\rm{16}}}{\rm{O}} \to {}^{24}{\rm{Mg}} + {}^4{\rm{He}}

The Formation of Stars

One 12C particle and one 16O particle react to produce a compound nucleus of 28Si which breaks up into a 24Mg nucleus and a 4He nucleus, i.e. it breaks up through the ‘α channel’ (a 4He nucleus is also called an alpha particle). In other reactions, such as