Optically visible post-AGB stars, post-RGB stars and young stellar objects in the Large Magellanic Cloud

Post-AGB stars as testbeds of nucleosynthesis in AGB stars

We construct a data base of 125 post-AGB objects (including R CrB and extreme helium stars) with published photospheric parameters (effective temperature and gravity) and chemical composition. We estimate the masses of the postAGB stars by comparing their position in the (log Teff , log g) plane with theoretical evolutionary tracks of different masses. We construct various diagrams, with the ai...

Stellar Evolution and Nucleosynthesis of Post-agb Stars

I discuss recent new models of post-Asymptotic Giant Branch stellar evolution. These models aim to clarify the evolutionary origin and status of a variety of hydrogen-deficient post-AGB stars such as central stars of planetary nebulae of Wolf-Rayet spectral type, PG1159 stars or Sakurai’s object. Starting with AGB models with overshoot such stars can evolve through one of four distinct channels...

Chemical composition of optically bright post-AGB stars

We present a detailed LTE chemical analysis of 10 optically bright F-type post-AGB objects on the basis of the analysis of high-resolution optical spectra and compare the results with similar objects discussed in the literature. The iron content is low on average, and so confirms the old and hence low-mass nature of the supergiants, with a noticable exception of HD 95767. We emphasize the fact ...

AGB stars in the Magellanic Clouds

Regions of different metallicity have been identified in the Magellanic Clouds by using the ratio between Asymptotic Giant Branch stars of spectral type C and M. In the Large Magellanic Cloud the ratio appears to decrease radially while in the Small Magellanic Cloud (SMC) there is no clear trend, reflecting either the large extension of the SMC along the line of sight or a more complex star for...

Agb Stars in the Magellanic Clouds