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(Referência obtida automaticamente do Web of Science, por meio da informação sobre o financiamento pela FAPESP e o número do processo correspondente, incluída na publicação pelos autores.)

2MASS J18082002-5104378: The brightest (V=11.9) ultra metal-poor star

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Autor(es):
Melendez, Jorge [1] ; Placco, Vinicius M. [2, 3, 4] ; Tucci-Maia, Marcelo [1] ; Ramirez, Ivan [5] ; Li, Ting S. [6] ; Perez, Gabriel [7]
Número total de Autores: 6
Afiliação do(s) autor(es):
[1] Univ Sao Paulo, IAG, Dept Astron, Rua Matao 1226, BR-05508900 Sao Paulo, SP - Brazil
[2] Univ Notre Dame, Dept Phys, Notre Dame, IN 46556 - USA
[3] Univ Notre Dame, JINA Ctr Evolut Elements, Notre Dame, IN 46556 - USA
[4] Univ Texas Austin, Dept Astron, RLM 15308, Austin, TX 78712 - USA
[5] Univ Texas Austin, McDonald Observ, Austin, TX 78712 - USA
[6] Texas A&M Univ, Dept Phys & Astron, College Stn, TX 77843 - USA
[7] Univ Sao Paulo, IAG, Dept Ciencias Atmosfer, Rua Matao 1226, BR-05508900 Sao Paulo, SP - Brazil
Número total de Afiliações: 7
Tipo de documento: Artigo Científico
Fonte: Astronomy & Astrophysics; v. 585, JAN 2016.
Citações Web of Science: 8
Resumo

Context. The most primitive metal-poor stars are important for studying the conditions of the early galaxy and are also relevant to big bang nucleosynthesis. Aims. Our objective is to find the brightest (V < 14) most metal-poor stars. Methods. Candidates were selected using a new method, which is based on the mismatch between spectral types derived from colors and observed spectral types. They were observed first at low resolution with EFOSC2 at the NTT to obtain an initial set of stellar parameters. The most promising candidate, 2MASS J18082002-5104378 (V = 11.9), was observed at high resolution (R = 50 000) with UVES at the VLT, and a standard abundance analysis was performed. Results. We found that 2MASS J18082002-5104378 is an ultrametal-poor star with stellar parameters T-eff = 5440 K, log g = 3.0 dex, v(t) = 1.5 kms(-1), {[}Fe/H] = -4.1 dex. The star has {[}C/Fe] < + 0.9 in a 1D analysis, or {[}C/Fe] less than or similar to + 0.5 if 3D effects are considered; its abundance pattern is typical of normal (non-CEMP) ultra metal-poor stars. Interestingly, the star has a binary companion. Conclusions. 2MASS J1808-5104 is the brightest (V = 11.9) metal-poor star of its category, and it could be studied further with even higher S/N spectroscopy to determine additional chemical abundances, thus providing important constraints to the early chemical evolution of our Galaxy. (AU)

Processo FAPESP: 10/50930-6 - Evolução química e populações estelares galácticas e extragalácticas, por espectroscopia e imageamento
Beneficiário:Beatriz Leonor Silveira Barbuy
Linha de fomento: Auxílio à Pesquisa - Temático
Processo FAPESP: 12/24392-2 - Espectroscopia de alta precisão: impacto no estudo de planetas, estrelas, a galáxia e cosmologia
Beneficiário:Jorge Luis Melendez Moreno
Linha de fomento: Auxílio à Pesquisa - Temático