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Alves Do Nascimento, S. Dissertaã§Ã£O De Mestrado UFRN/DFTE

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Alves Do Nascimento, S. Dissertaã§Ã£O De Mestrado UFRN/DFTE UNIVERSIDADE FEDERAL DO RIO GRANDE DO NORTE CENTRO DE CIÊNCIAS EXATAS E DA TERRA DEPARTAMENTO DE FÍSICA TEÓRICA E EXPERIMENTAL PROGRAMA DE PÓS-GRADUAÇÃO EM FÍSICA PROPRIEDADES FÍSICAS DE PLANETAS EXTRASOLARES Sânzia Alves do Nascimento Orientador: Prof. Dr. José Renan De Medeiros Dissertação apresentada ao Departamento de Físi- ca Teórica e Experimental da Universidade Fede- ral do Rio Grande do Norte como requisito parcial à obtenção do grau de MESTRE em FÍSICA. Natal, abril de 2008 Aos meus pais, por terem sido os responsáveis pelo evento mais importante da minha vida: meu nascimento. Na mesma pedra se encontram, Conforme o povo traduz, Quando se nasce - uma estrela, Quando se morre - uma cruz. Mas quantos que aqui repousam Hão de emendar-nos assim: “Ponham-me a cruz no princípio... E a luz da estrela no fim!” Mário Quintana (Inscrição para um portão de cemitério) Ser como o rio que deflui Silencioso dentro da noite. Não temer as trevas da noite. Se há estrelas no céu, refleti-las. E se os céus se pejam de nuvens, como o rio as nuvens são água, refleti-las também sem mágoa, nas profundidades tranqüilas. Manuel Bandeira (Estrela da vida inteira) Agradecimentos gradeço a mim mesma por ter tido coragem de levar adiante os sonhos de A Deus edoprofessor Renan em minha vida, e, por sonharem comigo, agradeço a ambos; a Deus, por tudo, inclusive pela fé que me faz agradecer a Ele antes de a qualquer um outro. Ao prof. Renan, pela paternidade científica e pelos bons vinhos. Aos professores Marizaldo Ludovico e João Manoel sou imensamente grata. Ao primeiro, por ter me mostrado os caminhos da Física; ao segundo por ter me ajudado a desvendar os segredos da poesia. A eles sou grata pelos tão belos ensinamentos, de cuja junção surgiu minha paixão pela Astrofísica. Agradeço - com a convicção de que sem eles não estaria aqui hoje - aos ilustres professores do DFTE, principalmente àqueles que me ensinaram Física e Matemática. Não posso citar todos, mas estaria negando meus sentimentos se não mencionasse os professores Rui Tertuliano de Medeiros, Janilo Santos e Carlos Chesman, exemplos de bons mestres. Ao professor Joaquim Elias,do departamento de matemática, agradeço pela paixão com que ensina. Aos colegas do DFTE agradeço pelos bons (e maus) exemplos de humanidade, moralidade e fraternidade que me deram ao longo desses anos, exemplos estes que iii me ajudaram a melhorar enquanto pessoa e aumentar meu empenho enquanto estudante. Em especial, ao Charlie Salvador eaoFábio Ferreira, pela alegria doce e descontraída da companhia amiga, crítica e sincera. Agradeço ainda aos colegas do grupo de astrofísica, por acreditarem em mim e por terem ajudado sempre que precisei. Especialmente, àqueles que se tornaram grandes amigos: ao Bruno Canto Martins eaoJefferson Soares por serem meus queridos irmãos aqui em Natal. E não poderia esquecer alguém que neste último ano tem se tornado parte de minha consciência: Sumaia Sales. Aos meus pais e irmãos sou grata pelo que sou, sem o que não poderia está cumprindo esta etapa da minha vida. Aos meus amigos queridos Hugo Juliano Duarte Matias e Anaxsandra Lima Duarte agradeço por terem sido minha família neste 2007 de esforço e dedicação à pesquisa. Aos demais amigos, igualmente queridos, e a minha minúscula família, agradeço por terem compreendido minha falta de tempo para o cinema, as con- versas e os passeios de fim de semana. Agradeço a eles por acreditarem em mim, e por terem me dado um espaço em suas vidas, embora eu não o tenha ocupado muito nestes últimos meses. Especialmente a Rosiana Clara, por ter estado na torcida o tempo todo, vibrando com minhas vitórias e me animando nos tropeços. Pelo apoio financeiro, tão bem representado pelo CNPq, pela FAPERN e pela UFRN, agradeço aos contribuintes (inclusive eu própria). iv Resumo OTAÇÃO é um dos importantes aspectos a ser observado na astrofísica estelar. Por R isto, neste trabalho, investigamos este parâmetro no estudo das estrelas hospedeiras de planetas. Parâmetro físico este que fornece informação sobre a distribuição do mo- mentum angular dos sistemas planetários, bem como sobre o seu papel nos mais difer- entes fenômenos, incluindo emissão cromosférica e coronal e sobre aqueles decorrentes de efeitos de maré. Apesar dos contínuos avanços feitos no estudo das características e das propriedades destes objetos, as principais características de seu comportamento rotatório ainda não estão bem estabelecidas. Neste contexto, o presente trabalho traz um estudo pioneiro sobre a rotação e o momentum angular das estrelas hospedeiras de planetas, bem como sobre a correlação entre rotação e parâmetros físicos estelares e planetários. Nossa análise é baseada em uma amostra de 232 planetas extrasolares, orbitando 196 estrelas de diferentes classes de luminosidade e tipos espectrais. Além do estudo do comportamento rotacional dessas estrelas, re-visitamos o comportamento das propriedades físicas destas estrelas e de seus planetas, incluindo a massa estelar e a metalicidade, bem como os parâmetros orbitais planetários. Como resultados princi- pais, podemos sublinhar que a rotação das estrelas com planetas apresenta duas claras características: estrelas com Tef inferiores a aproximadamente 6000 K possuem rotações mais baixas, enquanto que entre aquelas com Tef > 6000 K encontramos rotações mod- v eradas e altas, embora algumas exceções. Nós mostramos também que as estrelas com <J>∝ vα planetas seguem, em sua maioria, a lei do Kraft, a saber rot. Nesta mesma linha nós mostramos que a relação rotação versus idade das estrelas com planetas segue, ao menos qualitativamente, como qualquer outra estrela de campo ou de aglomerado, a lei de Skumanich e de Pace & Pasquini. Um resultado interessante a ser destacado é a relação rotação versus período orbital, que aponta para uma tendência de que as estrelas que abrigam planetas com período orbital menores apresentam rotações mais realçadas. vi Abstract OTATION is one the most important aspects to be observed in stellar astrophysics. R Here we investigate that particularly in stars with planets. This physical parame- ter supplies information about the distribution of angular momentum in the planetary system, as well as its role on the control of different phenomena, including coronal and cromospherical emission and on the ones due of tidal effects. In spite of the continu- ous solid advances made on the study of the characteristics and properties of planet host stars, the main features of their rotational behavior is are not well established yet. In this context, the present work brings an unprecedented study about the rotation and angular momentum of planet-harbouring stars, as well as the correlation between rotation and stellar and planetary physical properties. Our analysis is based on a sample of 232 ex- trasolar planets, orbiting 196 stars of different luminosity classes and spectral types. In addition to the study of their rotational behavior, the behavior of the physical properties of stars and their orbiting planets was also analyzed, including stellar mass and metalli- city, as well as the planetary orbital parameters. As main results we can underline that the rotation of stars with planets present two clear features: stars with Tef lower than about 6000 K have slower rotations, while among stars with Tef > 6000 K we find mode- rate and fast rotations, though there are a few exceptions. We also show that stars with <J>∝ vα planets follow mostly the Kraft´s law, namely rot. In this same idea we show vii that the rotation versus age relation of stars with planets follows, at least qualitatively, the Skumanich and Pace & Pasquini laws. The relation rotation versus orbital period also points for a very interesting result, with planet-harbouring stars with shorter orbital periods present rather enhanced rotation. viii Sumário Agradecimentos iii Resumo v Abstract vii Lista de Figuras xiv Lista de Tabelas xv Lista de Símbolos xvi 1 Introdução 1 1.1 Sobre a Nomenclatura Utilizada neste trabalho ............... 4 1.2 Ânimo e Plano deste trabalho ........................ 5 2 Revisão Teórica 6 2.1 Breve Revisão de Mecânica Celeste ..................... 6 ix 2.2 Momentum Angular Estelar ......................... 11 2.3 Momentum Angular Planetário ....................... 12 2.4 O que é um planeta? ............................. 13 2.5 Estrelas, Anãs Marrons e Planetas ..................... 15 2.5.1 Formação Estelar .......................... 16 2.5.2 Formação Planetária ......................... 18 2.5.2.1 Origem da nuvem protoplanetária ............ 19 2.5.2.2 Formação do disco .................... 20 2.5.2.3 Crescimento de partículas sólidas ............ 21 2.5.2.4 Formação dos planetesimais ............... 23 2.5.2.5 Formação e evolução dos planetas ............ 24 3 Métodos de Busca de Planetas Extrasolares 29 3.1 Métodos de Detecção de Planetas ...................... 29 3.1.1 Perturbação Dinâmica da Estrela .................. 33 3.1.1.1 Velocidade Radial ..................... 33 3.1.1.2 Posição Astrométrica ................... 35 3.1.1.3 Pulsar ........................... 36 3.1.2 Microlentes Gravitacionais ..................... 37 3.1.3 Fotometria: trânsito e reflexões ................... 37 3.1.3.1 Probabilidade de ocorrência de Trânsito ......... 38 3.1.3.2 Profundidade do Trânsito ................. 40 3.1.3.3 Duração do Trânsito .................... 41 x 3.2 Projetos de Busca de Planetas ........................ 42 4 Dados Observacionais 45 4.1 Base de Dados ................................ 45 4.2 Parâmetros Estelares ............................
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