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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.)

Chemical evolution models for the dwarf spheroidal galaxies Leo 1 and Leo 2

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Autor(es):
Lanfranchi, G. A. [1] ; Matteucci, F. [2, 3]
Número total de Autores: 2
Afiliação do(s) autor(es):
[1] Univ Cruzeiro Sul, Nucleo Astrofis Teor, BR-01506000 Sao Paulo - Brazil
[2] Univ Trieste, Dipartimento Astron, I-34131 Trieste - Italy
[3] Osserv Astron Trieste, INAF, I-34131 Trieste - Italy
Número total de Afiliações: 3
Tipo de documento: Artigo Científico
Fonte: Astronomy & Astrophysics; v. 512, MAR-APR 2010.
Citações Web of Science: 21
Resumo

Aims. We investigate the chemical evolutionary history of the dwarf spheroidal galaxies Leo 1 and Leo 2 by means of predictions from a detailed chemical evolution model compared to observations. The model adopts up to date nucleosynthesis and takes into account the role played by supernovae of different types (Ia, II), allowing us to follow in detail the evolution of several chemical elements (H, D, He, C, N, O, Mg, Si, S, Ca, Fe, Ba, and Eu). Methods. Each galaxy model is specified by the prescriptions of the star formation rate and by the galactic wind efficiency chosen to reproduce the main features of these galaxies, in particular the stellar metallicity distributions and several abundance ratios. These parameters are constrained by the star formation histories of the galaxies as inferred by the observed color magnitude diagrams, indicating extended star formation episodes occurring at early epochs, but also with hints of intermediate stellar populations. Results. The main observed features of the galaxies Leo 1 and Leo 2 can be very well explained by chemical evolution models according to the following scenarios: the star formation occurred in two long episodes at 14 Gyr and 9 Gyr ago that lasted 5 and 7 Gyr, respectively, with a low efficiency (v = 0.6 Gyr(-1)) in Leo 1, whereas the star formation history in Leo 2 is characterized by one episode at 14 Gyr ago that lasted 7 Gyr, also with a low efficiency (v = 0.3 Gyr(-1)). In both galaxies an intense wind (nine and eight times the star formation rate -w(i) = 9 and 8 in Leo 1 and Leo 2, respectively) takes place which defines the pattern of the abundance ratios and the shape of the stellar metallicity distribution at intermediate to high metallicities. Conclusions. The observational constraints can only be reproduced with the assumption of gas removal by galactic winds. (AU)

Processo FAPESP: 06/57824-1 - Aplicação de modelos teórico-computacionais em Astrofísica
Beneficiário:Gustavo Amaral Lanfranchi
Linha de fomento: Auxílio à Pesquisa - Apoio a Jovens Pesquisadores