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Carolina Chavero

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Carolina Chavero Ministerio´ de Cienciaˆ e Tecnologia Observatorio´ Nacional EVOLUC¸ AO˜ DE DISCOS CIRCUNSTELARES EM ESTRELAS DE BAIXA MASSA Carolina Chavero Tese realizada sob a orientac¸ao˜ do Prof. Dr. Ra- miro de la Reza e apresentada a` Divisao˜ de Pro- gramas de Pos-graduac¸´ ao˜ do Observatorio´ Nacional como requisito para a obtenc¸ao˜ do t´ıtulo de Doutor em Astronomia. Rio de Janeiro, Abril de 2009 Livros Grátis http://www.livrosgratis.com.br Milhares de livros grátis para download. ... Este trabalho ´ededicado especialmente para minha familia, que ´eminha base e meu maior orgulho, e tamb´em para todos aqueles que compartilham comigo o entusiasmo pela Astronomia. Conteudo´ Agradecimentos v Resumo ix Abstract xi Lista de Tabelas xiii Lista de Figuras xix 1 Motivac¸ao˜ 1 1.1 Contextohist´orico............................ 1 2 Discosdotipo debris 5 2.1 Descobertas............................... 5 2.2 M´etododedetecc¸˜ao. 6 2.2.1 Excessosinfravermelhos . 6 2.2.2 Imagensdiretas ........................ 8 2.2.3 Algumasimagens. .. .. .. .. .. .. 12 2.3 Buscas.................................. 15 2.4 Luminosidade: Fator fd ......................... 16 2.4.1 Evoluc¸˜ao temporal dos discos debris ............. 17 2.5 Tempodevidadodiscovs.massaestelar . 20 3 Estrelas com planetas extra-solares 23 3.1 Contextohist´orico. .. .. .. .. .. .. .. 23 3.2 T´ecnicasdedetecc¸˜ao . 25 3.2.1 T´ecnica espectrosc´opica: Velocidade radial (VR) ou Doppler 26 3.2.2 T´ecnica fotom´etrica: Trˆansito planet´ario . ....... 28 3.3 Propriedades dos planetas extra-solares e de suas estrelashospedeiras 29 3.3.1 Distribuic¸˜aodemassase´orbitas . 30 i ii 3.3.2 Metalicidade .......................... 32 3.4 Migrac¸˜aoplanet´aria. 35 4 Evoluc¸ao˜ de discos debris emvoltadeestrelasdebaixamassa 39 4.1 Introduc¸˜aoemotivac¸˜ao . 39 4.2 Amostradediscosresolvidos. 41 4.2.1 Idadesdaamostra.. .. .. .. .. .. .. 41 4.3 Diagramacor-cor ............................ 44 4.3.1 Discos debris resolvidosespacialmente . 44 4.3.2 Discos candidatos a tipo debris ................ 45 4.3.3 Distribuic¸˜ao de discos protoplanet´arios: Evidˆencia de uma regi˜ao de transic¸˜ao com discos debris ............. 56 4.4 Modelosdediscos ........................... 61 4.4.1 Omodelodetransferˆenciaradiativa . 62 4.4.2 Parˆametrosdeentradadomodelo . 62 4.5 Resultados dos modelos de transferˆencia radiativa . ....... 64 4.6 Modeloscolisionais. .. .. .. .. .. .. .. 74 4.7 Evoluc¸˜aodediscos:Conclus˜oes . .. 78 5 Metalicidade das estrelas com discos debris 81 5.1 Introduc¸˜ao................................ 81 5.2 Amostra................................. 84 5.3 Observac¸˜oes............................... 84 5.4 Determinac¸˜ao de parˆametros atmosf´ericos . ...... 84 5.5 Relac¸˜aoidade-metalicidade . 85 5.6 Estrelas com discos debris eplanetas ................. 89 5.7 Considerac¸˜oesfinais . 89 6 Excesso metalico´ em estrelas com planetas 93 6.1 Cen´arioprimordialoudepoluic¸˜ao? . ... 93 6.2 Cen´ariodepoluic¸˜aonasestrelaspostTTauri . ...... 95 6.2.1 “A possible stellar metallic enhancement in post-T Tauri stars by a planetesimal bombardment” ............... 95 6.3 Distribuic¸˜ao de metalicidade em estrelas gigantes complanetas . 107 6.3.1 “Evolved stars suggest an external origin of the enhanced me- tallicity in planet-hosting stars” ................ 107 6.4 Distribuic¸˜ao de elementos refrat´arios e vol´ateis das estrelas com pla- netasdescobertospeloCoRoT . 113 6.4.1 “Distribution of refractory and volatile elements in CoRoT exoplanets host stars” ..................... 113 iii 7 Conclusoes˜ Gerais 123 Bibliograf´ıa 129 iv Agradecimentos Nada na vida conquistamos sozinhos. Sempre precisamos de outras pessoas para alcanc¸ar nossos objetivos. Muitas vezes um simples gesto pode mudar nossa vida e contribuir para nosso sucesso. Este trabalho deve muito a algumas pessoas e instituic¸˜oes, as quais fico feliz de agradecer especialmente: • Ao meu orientador, o Dr. Ramiro de la Reza por milhares de motivos, mas especialmente porque n˜ao s´ose dedicou a me orientar, mas tamb´em me ensinou com o exemplo do dia-a-dia o que ´ea paix˜ao pela ciˆencia, conheci com ele a verdadeira essˆencia do cientista. Agradec¸o muito a oportunidade recebida e valorizo a confianc¸a em mim depositada. N˜ao sei quantos estudantes podem dizer que s˜ao colega de seu “chefe”, eu posso dizer e sentir isso e espero poder continuar trabalhando e aprendendo junto a vocˆe. Por tudo isso Ramiro eu serei sempre grata com a sua pessoa. • Ao Observat´orio Nacional (ON) por me abrir as portas da sua P´os-Graduac¸˜ao (PG) e por ter me sempre dado todo o apoio tanto, institucional como financeiro para desenvolver meu doutorado na maior tranq¨uilidade. Assim tamb´em a todos os integrantes da PG: professores, alunos e secret´arias/os, obrigada pelo trato cordial. • A` CAPES, que financiou a maior parte do meu doutorado e forneceu todo o auxilio necess´ario atrav´es do ON. • A` European Association for Research in Astronomy (EARA) por ter me conce- dido a bolsa Marie Curie no est´agio “sandu´ıche” no Instituto de Astrof´ısica de Canarias (IAC), possibilitando-me conhecer e interagir com outro instituto de pesquisa e todo o enriquecimento profissional que isso possibilita. • Ao Instituto de Astrof´ısica de Canarias, ao Dr. Garik Israelian e seu grupo de trabalho por ter me recebido e compartilhado suas pesquisa e dados comigo. v vi • A Claudio B. Pereira por ter me apresentado pela primeira vez o mundo da determinac¸˜ao das abundˆancias espectrosc´opicas, que parecia chinˆes para mim no comec¸o. Obrigada pela paciˆencia e tempo dedicado, e tamb´em pelo cafezi- nho do dia-a-dia que faz do ambiente de trabalho mais humano. • Aos meus queridos amigos e colegas argentinos, Fernando, Ren´ee Alvaro que amorteceram minha chegada ao Rio de Janeiro. Eu n˜ao sei que teria sido de mim sem vocˆes, com suas dicas e carinho tudo foi e ainda ´emais f´acil, vocˆes es- tiveram em cada detalhe, eu acho que at´eficaram cansados de tantas perguntas, Gracias! • Ao Dr. Luca Pasquini, por ter me convidado a participar da discuss˜ao da meta- licidade em estrelas gigantes com planetas, que deu como resultado uma linda e relevante publicac¸˜ao. Foi um prazer fazer parte dessa pesquisa e aprender sobre a organizac¸˜ao e discuss˜ao do trabalho em grupo. • A` professora Daniela Lazzaro por as inumer´aveis caronas e por compartilhar comigo tantas conversas sobre as diversas tarefas e responsabilidades que fazem parte da vida astronˆomica. • Ao grupo de dinˆamica do Dr. Othon Winter da UNESP, pelo trabalho em colaborac¸˜ao em uma ´area completamente nova para mim. • A todos meus colegas e amigos do ON que foram (´es˜ao) t˜ao importantes durante estes anos de dedicac¸˜ao `atese. Sou muito grata pela ajuda e carinho recebido seja no cursado das aulas, nos semin´arios ou nas horas de lazer. Particularmente agradec¸o a Aldinˆez, Vinicius, Manu, e Antonio que me aguentaram na etapa final com a famosa TPT (tens˜ao pr´etese). • A meus amigos e colegas do IAC, particularmente a Ren´e, Pablo e Santiago. Vocˆes foram minha fam´ılia em Tenerife, minha fam´ılia colombiana que sempre levarei no meu corac¸˜ao. • A` Dra. Natalia Drake, por todas suas dicas e ensinamentos na determinac¸˜ao de abundˆancias via s´ıntesis espectral; a sua ajuda foi muito importante para analizar os espectros das estrelas CoRoT’s. • As` organizac¸˜oes e intituc¸˜oes como a Uni˜ao Internacional de Astronomia (IAU), o Observat´orio do Vaticano, o Centro de Ciˆencia de Spitzer (SSC), a Socie- dade de Astronomia Brasileira (SAB) entre outras, que me permitiram assistir a reuni˜oes cient´ıficas de alto n´ıvel das quais aprendi muito e tive a possibilidade vii de conhecer os rostos atr´as de cada “paper”. Estas reuni˜oes me deram a opor- tunidade de fazer contatos de trabalho e conhecer pessoas maravilhosas de todo lugar do mundo. • Aos professores, amigos e colegas que conheci em congressos e escolas que enriqueceram minha vida profissional e pessoal. • A Roberto e Cinthia que tiveram o dificil´ıssimo e ´arduo trabalho de corrigir as diferentes vers˜oes desta tese escrita em portuguˆes por uma hispano-parlante. • Ao DTIN, mil vezes obrigada por me ajudar sempre que precisei. Particular- mente gostaria de agradecer a Marcio, Renato e Eduardo por a sua efetividade e energia sempre t˜ao positiva. • Ao meus amigos de toda a vida, los amichigos, e do OAC que torceram por mim desde C´ordoba. Gracias por el cari˜no y apoyo mandado en cada e-mail y cada visita. • As minhas colegas de casa pela paciˆencia, companheirismo e compreens˜ao, sa- bendo entender o lugar que a pesquisa ocupa na minha vida, obrigada mesmo!. • Ao Brasil por me dar a oportunidade de estudar aqui e conhecer este povo ma- ravilhoso que me fez sentir como na minha casa (tirando a ´epoca da copa do mundo). • Por ´ultimo, mas primeiros no meu pensamento, agradec¸o a minha fam´ılia pelo apoio contin´uo e incondicional. Sei que n˜ao foi f´acil no comec¸o entender e acei- tar a minha ausˆencia, mas com o tempo, ao ver-me satisfeita com meu trabalho e minha escolha, fico feliz que foram vocˆes os que me incentivaram ainda mais em seguir o caminho da minha vocac¸˜ao. viii Resumo ix O tema central desta tese ´ea evoluc¸˜ao global de discos circunstelares em estrelas de baixa massa desde a etapa protoplanet´aria at´ea debris atrav´es de uma an´alise no in- fravermelho. Estudamos tamb´em nesta tese mais um tema, a composic¸˜ao qu´ımica das estrelas com planetas e a sua relac¸˜ao com a formac¸˜ao planet´aria. Ambos temas dispa- res a priori, no entanto conseguimos encontrar o nexo entre eles. Nossa contribuic¸˜ao principal est´acentrada na caracterizac¸˜ao da evoluc¸˜ao dos discos debris mediante o uso de um ´unico diagrama constru´ıdo com fluxos em 12, 24 e 70 µm observados princi- palmente pelo sat´elite Spitzer.
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