Evolution of Stars: The Photospheric Abundance Connection

ISBN-13: 9780792311287 / Angielski / Miękka / 1991 / 487 str.

G. Michaud; A. Tutukov

Opis

G. MICHAUD Dipartement de Physique Universiti de Montrial c. P. 6128, succursale A Montrial, Que., H3C 317 Canada The aim of IAU Symposium 145 was to use the photospheric abundances of the chemical elements to give us some hint of the past evolution and of the current structure of stars. At the invitation on the Bulgarian Academy o/Sciences, it brought together one hundred and fifty one scientists from 21 countries to 71atni Pjasaci (Golden Sands), Bulgaria, for a five day meeting. The processes discussed included accretion, mass loss, mass exchange, convection, turbulence, meridional circulation, and diffusion in addition to nuclear reactions. Observationally, spectroscopy was involved. New telescopes and instruments have considerably extended the scope of spectroscopy over the last few years. Space telescopes, such as IUE, have allowed the development of far UV spectroscopy. The access to the infrared has proven critical for probing cool stars. Large ground based telescopes have allowed fainter objects to be observed especially when they are equipped with more efficient detectors such as CCDs and Reticons. The co-adding of digitalized photographic plates has extended their usefulness. It has become possible to make high resolution, high signal to noise observations of objects that could only be observed at low resolution in former days. Weak lines can now be measured with accuracy, allowing the precise determination of the abundances of elements as rare as lithium and the determination of precise limits to isotopic ratios.

Spis treści

Setting The Stage.- Elements in the Cosmos: Origin of the Light Elements.- Chemical Evolution of Galaxies: Abundance Trends and Implications.- Supernova Abundance Generation.- Limitations of Stellar Abundance Determinations.- Model Atmospheres and Chemistry.- The Lower Main Sequence.- Solar Abundances: the Reference System.- Mixing due to Angular Momentum Transfer in Evolving Sun-like Stars.- Lithium and Beryllium in Main Sequence Stars.- The Fm-Am stars: Observed Anomalies.- Diffusion, Meridional Circulation and Mass Loss in Main Sequence and Horizontal Branch Stars.- The Upper Main Sequence.- The CNO-cycle Elements in Atmospheres of B-type Main Sequence Stars.- Non Magnetic Anomalous Stars: The HgMn Stars -A Review of Elemental Abundances.- Magnetic Ap Stars: Evolutionary Status and Abundance Anomalies.- Spectroscopy and Geography of Magnetic Ap Stars: Implications for Structure.- Intermediate He Rich Stars.- Are There Normal Upper Main Sequence Stars: ? Bootis.- The Giants.- Abundances in Wolf-Rayet Stars, LBVs and OBN Stars.- The Chemical Composition of the Wolf-Rayet Envelopes.- Chemical Abundances and Models of WR Stars and Blue Supergiants.- CNO Abundances of Stars Undergoing First Dredge Up Mixing.- [Fe/H] Ratios in Population II Stars.- The Agb.- Asymptotic Giant Branch Stars: Thermal Pulses, Carbon Production, and Dredge Up; Neutron Sources and s-process Nucleosynthesis.- On Low Mass AGB Stars.- A Brief Review of the s-process of Nucleosynthesis.- The Chemical Composition of Asymptotic Giant Branch Stars - The s-process.- Technetium in Stellar Atmospheres.- Turbulence and the Lithium Abundance in Giants and Main-Sequence Disk and Halo Stars.- Chemical Composition of Post-AGB Stars.- Horizontal Branch Stars and Binaries.- Binarity and Abundance Anomalies in Stars.- Atmospheres and Abundances of Blue Horizontal Branch Stars and Related Objects.- The Planetary Nebulae.- Photospheric Abundances in Central Stars of Planeteray Nebulae, and Evolutionary Implications.- Stellar Mixing from Galactic and Magellanic Cloud Planetary Nebulae Abundances.- White Dwarfs.- Pre-White Dwarf Evolution through Planetary Nebulae.- Abundance Patterns in White Dwarfs.- Successes and Challenges of the Theory of White Dwarf Spectral Evolution.- Stratification in White Dwarf Atmospheres.- Concluding Remarks.- Concluding Remarks (I).- The Abundance Connection - The View from the Trenches.- Some Closing Thoughts.- List of Participants.