Published in Publications of the Astronomical Society of Australia, Volume 31, id.e030
http://arxiv.org/abs/1405.0062

For a PDF version of the article, click here.

Abstract: The chemical evolution of the Universe is governed by the chemical yields from stars, which in turn are determined primarily by the initial stellar mass. Even stars as low as 0.9 M_⊙ can, at low metallicity, contribute to the chemical evolution of elements. Stars less massive than about 10 M_⊙ experience recurrent mixing events that can significantly change the surface composition of the envelope, with observed enrichments in carbon, nitrogen, fluorine, and heavy elements synthesized by the slow neutron capture process (the s-process). Low- and intermediate-mass stars release their nucleosynthesis products through stellar outflows or winds, in contrast to massive stars that explode as core-collapse supernovae. Here we review the stellar evolution and nucleosynthesis for single stars up to ~ 10 M_⊙ from the main sequence through to the tip of the asymptotic giant branch (AGB). We include a discussion of the main uncertainties that affect theoretical calculations and review the latest observational data, which are used to constrain uncertain details of the stellar models. We finish with a review of the stellar yields available for stars less massive than about 10 M_⊙ and discuss efforts by various groups to address these issues and provide homogeneous yields for low- and intermediate-mass stars covering a broad range of metallicities.

Keywords: stars: AGB and post-AGB - nucleosynthesis - ISM: composition - Population II stars - stars: mixing - chemical evolution

The Dawes Reviews are substantial reviews of topical areas in astronomy, published by authors of international standing at the invitation of the PASA Editorial Board. The reviews recognise William Dawes (1762-1836), second lieutenant in the Royal Marines and the astronomer on the First Fleet. Dawes was not only an accomplished astronomer, but spoke five languages, had a keen interest in botany, mineralogy, engineering, cartography and music, compiled the first Aboriginal-English dictionary, and was an outspoken opponent of slavery.

Table of Contents

• INTRODUCTION
• Definitions and Overview of Evolution
• The Lowest Mass Stars
• The Low Mass Stars
• The Intermediate Mass Stars
• The Lower Intermediate Mass Stars
• The Middle Intermediate Mass Stars
• The Massive Intermediate Mass Stars
• The Massive Stars
• Stellar Yield Calculations
• EVOLUTION AND NUCLEOSYNTHESIS PRIOR TO THE ASYMPTOTIC GIANT BRANCH
• Illustrative Examples
• First Dredge-Up
• Abundance Changes due to FDU
• The Onset of FDU
• The Bump in the Luminosity Function
• The Need for Extra-Mixing
• The ³He problem
• Non-convective mixing processes on the First Giant Branch
• The onset of extra mixing
• Rotation
• Parameterised models
• Thermohaline mixing
• Magnetic Fields and Other Mechanisms
• Lithium
• Second Dredge-Up
• Variations at low metallicity
• Curtailing First Dredge-Up
• The Core Helium Flash
• Proton Ingestion Episodes
• EVOLUTION AND NUCLEOSYNTHESIS DURING THE ASYMPTOTIC GIANT BRANCH
• The thermally-pulsing Asymptotic Giant Branch
• Hot bottom burning
• Dredge-up, HBB and the Brightest C Stars
• The Core-Mass vs Luminosity Relation
• Third dredge up
• The Dredge-Up Parameter
• The Carbon Star Luminosity Function and other Observational Constraints
• Nucleosynthesis during Asymptotic Giant Branch Evolution
• Nucleosynthesis via thermal pulses
• The carbon isotopic ratio: ¹²C / ¹³C
• Nitrogen isotopic ratios
• The Intershell Oxygen Abundance
• Fluorine
• Other Species in the Intershell
• Heavy Magnesium isotopes
• Planetary nebulae and post-AGB stars
• Nucleosynthesis from Hot Bottom Burning
• C, N, and O
• Ne, Na, Mg, and Al
• Lithium
• Type I planetary nebulae
• The slow neutron capture process
• Neutron sources in AGB stars
• The formation of ¹³C pockets
• The s-process in low-mass AGB stars
• The s-process in intermediate-mass AGB stars
• Proton ingestion episodes: PIEs
• Overview of 1D PIEs
• 1D PIEs and the i-process
• Yields from 1D PIEs
• Multi-dimensional PIE calculations
• Beyond the AGB: Super-AGB stars
• Super-AGB Evolution
• Third Dredge-Up
• Super-AGB Nucleosynthesis
• Final fates of AGB and Super-AGB stars
• MAJOR UNCERTAINTIES
• Convection and the third dredge up
• Determining the Borders of Convection
• Structural Changes from Convection
• Mass loss
• Extra mixing in AGB stars
• Low temperature Opacities
• The s-process
• Binary evolution
• CHEMICAL ENRICHMENT FROM AGB STARS
• Stellar yields from AGB stars
• Summary of elements produced by low and intermediate-mass stars
• Lithium
• Carbon, Nitrogen, Oxygen
• Fluorine
• From Neon to Iron
• Heavy elements produced by the s-process
• SUMMARY AND OUTLOOK
• REFERENCES