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Differential Abundances in Metal-Poor Stars

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Universidade de S~aoPaulo Instituto de Astronomia, Geof´ısicae Ci^enciasAtmosf´ericas Departamento de Astronomia Henrique Marques Reggiani Differential abundances in metal-poor stars: impact in the study of the Galaxy, stellar evolution and Big Bang nucleosynthesis S~aoPaulo 2019 Henrique Marques Reggiani Differential abundances in metal-poor stars: impact in the study of the Galaxy, stellar evolution and Big Bang nucleosynthesis Tese apresentada ao Departamento de Astro- nomia do Instituto de Astronomia, Geof´ısica e Ci^enciasAtmosf´ericas,departamento de As- tronomia, da Universidade de S~aoPaulo, como requisito parcial para a obten¸c~aodo t´ıtulode Doutor em Ci^encias.Vers~aocorrigida. O ori- ginal encontra-se dispon´ıvel na Unidade. Area´ de Concentra¸c~ao:Astronomia Orientador: Prof. Dr. Jorge Mel´endez S~aoPaulo 2019 I dedicate this work to my wife, my mother, and my father! Acknowledgements Since I finished my undergrad there is one person that stood by my side, helping both in the good and bad moments. Thank you for all the help, for reading both my dissertation and thesis, which must have been excruciatingly boring for a person that studies languages, thank you for acompaning me to other countries, both in the past and in the future. Thank you for always being there for me. Thank you Maysa! Thanks to both my parents, without you I would never have had the oportunity, or conditions, to go to a good school and into a public university, which allowed me to get here, trying to get a PhD title. Thanks for the education, both formal and social, and helping me become who I am today. Thanks to all my friends, old and new ones, for the jokes and laughs, for the beers, barbecues and parties. Thank you Jorge, for all the advice and help during these long years. You certainly helped me become a better researcher. Hopefully I will still be able to learn much from you in our future projects together. Thank you to everyone, not named here, that helped during my life. I could not possibly mention everyone here, but I am sure you know who you are! \Somewhere, something incredible is waiting to be known." Carl Sagan \There is a great deal of difference between an eager man who wants to read a book and the tired man who wants a book to read" GK Chesterton Resumo Nesta tese apresentamos os resultados do trabalho de doutoramento desenvolvido no Instituto de Astronomia, Geof´ısicae Ci^enciasAtmosf´ericas,da Universidade de S~aoPaulo, publicados em quatro artigos cient´ıficoscomo primeiro autor, e um artigo arbitrado em \proceedings". Todos os artigos est~aoanexados no Ap^endiceA. O interesse principal deste trabalho de doutorado ´eestudar a forma¸c~aoe evolu¸c~aoqu´ımica da Gal´axiaatrav´esde an´alisesprecisas de abund^anciasqu´ımicas de estrelas pobres em metais do componente in- terno do halo gal´actico. Exploramos a viabilidade do uso da t´ecnicade an´alise diferencial e mostramos que o aumento em precis~aofornecido pelo uso da t´ecnica´ecapaz de revelar inomogeneidades n~aoobserv´aveis em uma an´alisecl´assica. Tamb´em´ediscutido como a resolu¸c~aoe o sinal/ru´ıdodos espectros, pode influenciar a precis~aofinal das abund^ancias obtidas, analisando espectros de diferentes qualidades de forma sistem´atica.Em seguida, ´e apresentado um trabalho de an´alisequ´ımicaatrav´esda t´ecnicadiferencial, onde s~aodiscu- tidas a forma¸c~aodo componente interno do halo gal´aticoe a evolu¸c~aoqu´ımicade diversos elementos, com implica¸c~oespara processos de nucleoss´ıntese e modelos de evolu¸c~aoqu´ımica da Gal´axia.Como subproduto deste estudo apresentamos uma an´aliseda evolu¸c~aode es- trelas bin´ariasatrav´esda an´alisequ´ımicade duas estrelas Blue Stragglers, com implica¸c~oes para a nucleoss´ıntese em estrelas AGB e para a evolu¸c~aode sistemas bin´arios. Tamb´em mostramos resultados de um estudo de um par de estrelas bin´arias,focado na forma¸c~aodo halo e no uso da t´ecnicade \chemical tagging" para a identifica¸c~aodo local de nascimento de duas estrelas extra-gal´aticas.Uma diferen¸caentre as abund^anciasdo par de estrelas ´e evid^enciade forma¸c~aoplanet´ariaem estrelas de baixa metalicidade. Finalizando a tese, mostramos o desenvolvimento de um modelo at^omicopara estudar a forma¸c~aodas linhas espectrosc´opicasde pot´assio,e a aplica¸c~aodeste modelo no estudo da evolu¸c~ao qu´ımica do elemento, mostrando que, possivelmente, estrelas massivas em alta rota¸c~aopodem ser uma importante fonte nucleossint´eticade pot´assio. Abstract This thesis presents the main results of the studies developed during the PhD at the Instituto de Astronomia, Geof´ısicae Ci^enciasAtmosf´ericas,of the Universidade de S~ao Paulo, that resulted in four papers as the first author and one peer-reviewed proceeding. All papers are attached in Appendix A. The main interest throughout the PhD is to study the Formation and early Chemical Evolution of the Galaxy via precise chemical abundan- ces of the metal-poor component of the Galactic inner halo. We explored the viability of a chemical analysis via line-by-line differential abundance analysis in low metallicity stars, and showed that the increased precision might reveal small differences and inhomo- geneities that can not be seen in a regular spectroscopic analysis. For this, we employed extremely high-resolution, and high S/N spectra, and we also showed how the quality of our data influences the final abundance precision. The line-by-line differential abundance technique was employed in a larger sample of high-resolution, high S/N, spectra, to study the formation of the inner halo and put constraints on chemical evolution models and the nucleosynthesis processes therein. As byproduct of our analysis, we studied binary stellar evolution through Blue Straggler Stars, which were used to constrain both nucleosynthesis in AGB stars and Blue Straggler formation. We also present the results of a study focused on a pair of binary stars with implications for the formation of the inner halo and the use of chemical tagging to constrain the birth environment of the stars. As a byproduct of this analysis we found implications of possible planetary formation in metal-poor stars. At last, we show the development of an atomic model for a non-LTE analysis of potassium line formation, and its application for the study of the chemical evolution of potassium th- rough cosmic history, with implications for the nucleosynthesis of potassium and Galactic chemical evolution models with yields from massive rotating stars. List of Figures 1.1 Spectra of stars with different metallicities . 25 1.2 Geometry for the definition of radiative intensity . 27 1.3 Geometry of a star . 28 1.4 Neutral hydrogen bound-free absorption cross-sections . 33 1.5 Natural atomic transition . 37 1.6 Energy of atomic levels as a function of the distance to the perturber . 39 1.7 The growth of the Hjerting function for different damping parameters. 42 1.8 Equivalent width definition . 46 1.9 Curve of Growth and line profile . 47 1.10 Spectra reduction example for a differential analysis . 49 2.1 The stellar parameters of CD -24 17504 determined using q2......... 57 2.2 Error ratios in stellar parameters from a classical (absolute) and a differential analysis. 62 2.3 Error ratios in chemical abundances from a classical (absolute) and a diffe- rential analysis. 63 2.4 Differential [X=H] abundances of stars G 64-37 and CD -2417504. 65 2.5 Differential [X=Fe] abundances of stars G 64-37 and CD -24 17504. 68 2.6 Progenitor of star CD -24 17504 via abundance pattern fit. 72 3.1 Kinematics of the dual halo. 77 3.2 Metallicity distribution function of the stellar halo. 78 3.3 Chemical abundances of α-elements in the solar neighborhood. 80 3.4 Toomre diagram for the high-α and low-α stars. 81 3.5 Chemical abundances of Na, Mg, Si, Ca, Ti, Cr, and Ni as a function of [Fe=H]....................................... 84 3.6 Metallicity distribution function of the Solar neighborhood. 86 3.7 Supernovae yields as a function of initial stellar masses. 88 3.8 Nickel abundances as a function of metallicity. 90 3.9 Abundances as a function of metallicity. 95 3.10 Lithium abundances as a function of [Fe=H]. 97 3.11 Lithium abundances as a function of Teff .................... 98 3.12 HR diagram of the globular cluster M80. 100 3.13 Lithium line in our BSS and in \normal" turn-off stars. 102 4.1 Differential equilibrium plots for star HD 134440. 109 4.2 Chemical abundances of stars HD 134439/134440 and samples of comparison.113 4.3 Chemical abundances as a function of condensation temperature. 114 4.4 Chemical abundances as a function of condensation temperature and atomic number, in a differential analysis of the binary pair 16 Cyg. 115 4.5 Chemical abundances as a function of condensation temperature of stars HD 134439/134440, relative to the solar abundance, from Chen and Zhao (2006). 116 4.6 Comparison between the chemical abundances of HD 134439 and HD 134440, as a function of condensation temperature. 118 5.1 Potassium nucleosynthesis in Supernovae explosions. 120 5.2 Potassium abundances and GCE prediction. 121 5.3 Potassium GCE models. 122 5.4 The Potassium 7698 A˚ resonance line in the Sun, HD 192263, and Procyon. 123 5.5 Chemical evolution of the elements as a function of stellar age, using solar twins....................................... 125 5.6 Differential abundances between the binary stars 16 Cyg A and B, as a function of condensation temperature.
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