Volume 431, Number 2, February IV 2005
|Page(s)||565 - 574|
|Section||Stellar structure and evolution|
|Published online||04 February 2005|
Departamento de Física, UFES, Av. Fernando Ferrari 514, 29075-910, Vitória, ES, Brazil e-mail: email@example.com
2 GEMAC, Depto. de Astronomia, OV/UFRJ, Ladeira Pedro Antonio 43, 20080-090, Rio de Janeiro, RJ, Brazil
3 Departamento de Astronomia, IAG/USP, Rua do Matão, 1226, Cidade Universitária, 05508-900, São Paulo, SP, Brazil
Accepted: 27 August 2004
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.
Key words: stars: AGB and post-AGB / stars: circumstellar matter / stars: evolution / ISM: planetary nebulae: general / infrared: stars
© ESO, 2005
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.