An analysis of the composite stellar population in M32

Autor(es)

Coelho, P. ^[1] ; de Oliveira, C. Mendes ^[2] ; Fernandes, R. Cid ^[3]

Afiliação do(s) autor(es)

^[1] Univ Paris 06, Inst Astrophys, CNRS, F-75014 Paris - France

^[2] Univ Sao Paulo, IAG, BR-05508900 Sao Paulo - Brazil

^[3] Univ Fed Santa Catarina, Dept Fis, CFM, BR-88040900 Florianopolis, SC - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Monthly Notices of the Royal Astronomical Society; v. 396, n. 2, p. 624-634, June 2009.
• Área do conhecimento: Ciências Exatas e da Terra - Astronomia
• Notas: O artigo consta como produto de dois processos: 05/03840-3 em nome de Paula Rodrigues Teixeira Coelho; 06/56213-9 em nome de Reuven Opher
• Citações Web of Science: 29
• Assunto(s): Formação e evolução da galáxia Meio interestelar Aglomerados de galáxias Nebulosas

Resumo

We obtained long-slit spectra of high signal-to-noise ratio of the galaxy M32 with the Gemini Multi-Object Spectrograph at the Gemini-North telescope. We analysed the integrated spectra by means of full spectral fitting in order to extract the mixture of stellar populations that best represents its composite nature. Three different galactic radii were analysed, from the nuclear region out to 2 arcmin from the centre. This allows us to compare, for the first time, the results of integrated light spectroscopy with those of resolved colour-magnitude diagrams from the literature. As a main result we propose that an ancient and an intermediate-age population co-exist in M32, and that the balance between these two populations change between the nucleus and outside one effective radius (1reff) in the sense that the contribution from the intermediate population is larger at the nuclear region. We retrieve a smaller signal of a young population at all radii whose origin is unclear and may be a contamination from horizontal branch stars, such as the ones identified by Brown et al. in the nuclear region. We compare our metallicity distribution function for a region 1 to 2 arcmin from the centre to the one obtained with photometric data by Grillmair et al. Both distributions are broad, but our spectroscopically derived distribution has a significant component with [Z/Z O]<=-1 , which is not found by Grillmair et al. (AU)

• Processo FAPESP: 05/03840-3 - A populacao estelar de m32 atraves da analise combinada de dados fotometricos e espectroscopicos.
• Beneficiário: Paula Rodrigues Teixeira Coelho
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 06/56213-9 - Nova física no espaço: formação e evolução de estruturas no universo
• Beneficiário: Claudia Lucia Mendes de Oliveira
• Modalidade de apoio: Auxílio à Pesquisa - Temático