Talk abstract details
Post-AGB stars of the LMC and SMC
Abstract
Post-AGB stars evolve on a fast track and systematic searches of the rare objects in external galaxies, only became possible after the release of deep infrared surveys. We exploited the release of the infrared LMC and SMC SAGE-Spitzer surveys and we searched for luminous, optically bright stars with infrared colours indicative of a past history of heavy dusty mass loss. Additionally, we executed a complete low-resolution spectral survey at Siding Spring, Australia, and at SAAO (South-Africa). Our final result consists of some 1400 good candidate post-AGB stars in the LMC alone. This full LMC catalogue was recently accepted for publication (van Aarle et al., 2011, A&A in press).
We studied several objects already in detail using both high-resolution optical spectra (which allow us to determine the abundances of a wide range of elements, from CNO up to the heaviest s-process elements) and low resolution IR spectra (to study the circumstellar dust properties). The abundances are modeled using state-of-the-art chemical stellar evolution AGB models.
The unique spectral characteristics of post-AGB stars, together with the newly defined large sample, covering a wide range in luminosities and metallicities, with well constrained distances, make that these objects provide unprecedented direct tests for the poorly understood final structure and chemical evolution of solar-like stars. The ultimate goal is to use these unique properties of post-AGB stars, to gain insight in the badly understood AGB nucleosynthesis and its dependency on metallicity and initial mass as well as to learn more on the connection between post-AGB stars and the PNe samples of both Magellanic clouds. We propose here a contributed talk to give a status report of our ongoing research.
We studied several objects already in detail using both high-resolution optical spectra (which allow us to determine the abundances of a wide range of elements, from CNO up to the heaviest s-process elements) and low resolution IR spectra (to study the circumstellar dust properties). The abundances are modeled using state-of-the-art chemical stellar evolution AGB models.
The unique spectral characteristics of post-AGB stars, together with the newly defined large sample, covering a wide range in luminosities and metallicities, with well constrained distances, make that these objects provide unprecedented direct tests for the poorly understood final structure and chemical evolution of solar-like stars. The ultimate goal is to use these unique properties of post-AGB stars, to gain insight in the badly understood AGB nucleosynthesis and its dependency on metallicity and initial mass as well as to learn more on the connection between post-AGB stars and the PNe samples of both Magellanic clouds. We propose here a contributed talk to give a status report of our ongoing research.