Explaining Lithium Enriched Red Giant Branch Stars

By Claudia Aguilera-Gómez

Contents1 Introduction 11.1 Stellar evolutionary models . . . . . . . . . . . . . . . . . . . . . . . . 21.2 Lithium in astrophysics . . . . . . . . . . . . . . . . . . . . . . . . . . 31.2.1 Big Bang Nucleosynthesis and the Lithium Problem . . . . . . 41.2.2 Chemical Enrichment of the Galaxy . . . . . . . . . . . . . . . 71.2.3 Lithium in stars . . . . . . . . . . . . . . . . . . . . . . . . . . 81.3 Red Giant Branch Stars . . . . . . . . . . . . . . . . . . . . . . . . . 111.3.1 Lithium rich giants . . . . . . . . . . . . . . . . . . . . . . . . 141.4 Outline of this thesis . . . . . . . . . . . . . . . . . . . . . . . . . . . 19I Scenarios of Lithium enrichment 212 Internal Mechanisms 222.1 Rotationally-induced mixing . . . . . . . . . . . . . . . . . . . . . . . 242.2 Thermohaline mixing . . . . . . . . . . . . . . . . . . . . . . . . . . . 282.3 Magnetic mechanisms and Magneto-Thermohaline Mixing . . . . . . 312.4 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 333 External Mechanisms 353.1 Binary companions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 353.2 Substellar companion engulfment . . . . . . . . . . . . . . . . . . . . 393.2.1 Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 403.2.2 Point of SSC dissipation . . . . . . . . . . . . . . . . . . . . . 453.2.3 Evolution of the supercial Li abundance . . . . . . . . . . . . 533.2.4 Rates of Li-enrichment . . . . . . . . . . . . . . . . . . . . . . 663.2.5 SSC models in perspective . . . . . . . . . . . . . . . . . . . . 723.2.6 Other observational constraints . . . . . . . . . . . . . . . . . 763.2.7 Evolution of 6Li abundance . . . . . . . . . . . . . . . . . . . 783.3 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85II Observational Applications 914 Trumpler 20 944.1 The possibility of extra mixing in the Trumpler 20 giants . . . . . . . 954.2 The two Li-rich giants in Trumpler 20: Possible engulfment . . . . . . 1014.3 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1045 Field Giants 1055.1 Sample selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1065.2 Measuring the Li abundance of the sample . . . . . . . . . . . . . . . 1095.3 Comparison with other works . . . . . . . . . . . . . . . . . . . . . . 1215.4 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1225.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1246 Stars with low main sequence Li abundances 1276.1 Assembling the catalog . . . . . . . . . . . . . . . . . . . . . . . . . . 1286.2 An overview of the catalog . . . . . . . . . . . . . . . . . . . . . . . . 1376.3 The lithium desert . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1416.3.1 Characterizing the Li desert: Mass and metallicity . . . . . . . 1436.3.2 Characterizing the Li Desert: Evolutionary stage . . . . . . . 1456.3.3 The origin of the Li Desert . . . . . . . . . . . . . . . . . . . . 1486.4 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1586.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159III Summary and Future Work 163Bibliography 183

• Format: Hardcover
• Language: English
• ISBN: 3030025829
• ISBN13: 9783030025823
• Release Date: December 2018
• Publisher: Springer
• Length: 131 Pages
• Weight: 0.85 lbs.
• Dimensions: 0.4" x 6.1" x 9.2"