Autor(es)

Ortiz, R. ; Lorenz-Martins, S. ; Rangel, E. M. ; Maciel, W. J. ^[4]

• Tipo de documento: Artigo Científico
• Fonte: Astronomy & Astrophysics; v. 431, n. 2, p. 565-574, 2005.
• Área do conhecimento: Ciências Exatas e da Terra - Astronomia
• Localização: ARQUIVO FAPESP
• Assunto(s): Galáxias Astrofísica estelar

Resumo

We investigate the evolution of oxygen- and carbon-rich AGB stars, post-AGB objects, and planetary nebulae using data collected mainly from the MSX catalogue. Magnitudes and colour indices are compared with those calculated from a grid of synthetic spectra that describe the post-AGB evolution beginning at the onset of the superwind. We find that carbon stars and OH/IR objects form two distinct sequences in the ( K-[8.3] [8.3]-[14.7]) MSX colour diagram. OH/IR objects are distributed in two groups: the bluest ones are crowded near [14.7]-[ 21.3 and [8.3]-[ 14.7 , and a second, redder group is spread over a large area in the diagram, where post-AGB objects and planetary nebulae are also found. High mass-loss rate OH/IR objects, post-AGB stars, and planetary nebulae share the same region in the ( K-[8.3] [8.3]-[14.7]) and [14.7]-[ 21.3 [8.3]-[14.7]) colour-colour diagrams. This region in the diagram is clearly separated from a bluer one where most OH/IR stars are found. We use a grid of models of post-AGB evolution, which are compared with the data. The gap in the colour-colour diagrams is interpreted as the result of the rapid trajectory in the diagram of the stars that have just left the AGB. (AU)

• Processo FAPESP: 02/08816-5 - Nebulosas fotoionizadas, estrelas e evolução química de galáxias
• Beneficiário: Walter Junqueira Maciel
• Modalidade de apoio: Auxílio à Pesquisa - Temático