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First Stars III
Contact:
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Poster
Title: Explosive end of high mass primordial AGB stars -- Supernova type 1.5 Author(s): Herbert Lau Abstract: We use the Cambridge stellar evolution code STARS to model the evolution of 5 and 7 solar mass zero-metallicity stars. With enhanced resolution at the hydrogen and helium burning shell in the AGB phases, we are able to model the entire thermally pulsing- asymptotic giant branch phase of around 600 thermal pulses. The helium luminosities of the thermal pulses are significantly lower than in higher metallicity stars so there is no third dredge up. The thermal pulses grow weaker as the core size increases and ceases eventually. From then on the star enters a quiescent burning phase which lasts until carbon ignites at the centre of the core and the CO core mass is very close to Chandrasakar mass and degenerate. We expect these stars to explode as a type 1.5 supernovae, very similar to Type Ia supernovae but inside a hydrogen rich envelope. We have also investigated whether various theoractical mass loss rates would cause the stars to lose its envelope before carbon ignition, thus preventing the supernova from occuring. There is no s-process enrichment because there is no third dredge up.
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